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Title: Microscopes and Accessory Apparatus - Catalogue No. 40
Author: Leitz, Ernst
Language: English
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  CATALOGUE No. 40.

  MICROSCOPES
  AND
  ACCESSORY APPARATUS.

  ERNST LEITZ
  WETZLAR
  GERMANY.

  Founded in 1850.

  Branch Offices:
  NEW-YORK:                CHICAGO:            BERLIN NW.
  411 West 59th Str.    32-38 Clark Str.    45 Luisenstrasse.
  30 East 18th Street.

  1903.

  =„Highest award“= Worlds Columbian Exhibition =Chicago 1893=.



  Contents.


  New constructions                            5
  Objectives and Eye-pieces                    7
  Stands                                      16
  Illuminating Apparatus                      20
  Complete Microscope Outfits                 24
  Microscopes for Mineralogical Research      57
  Dissecting Microscopes and Lupes            62
  Apparatus for Blood Examinations            70
  Micrometers                                 73
  Drawing Apparatus                           74
  Mechanical Stages                           78
  Photo-micrographic Apparatus                82
  Projection Apparatus (Edinger)              84
  The Large Projection Apparatus              87
  Microtomes                                  92
  Miscellaneous Accessories                   99
  Publications                               104
  Index                                      105



  Notice.


All previous editions of this catalogue are superceded by the present
one, which should be exclusively used in ordering.

Orders will be filled at once after their receipt.

In ordering care should be taken to give the =number= of each article
desired and to state listprice.

To avoid delay and misunderstandings, we request that name and address
be plainly written.

Goods are forwarded at the expense and risk of the purchaser.

Our instruments for use in =Universities, Colleges, Schools= &c. of the
=United States= are by law free of duty and we shall be pleased to make
specially low quotations for such orders.

  ERNST LEITZ.



  New Constructions.


Since issueing our last catalogue, a number of new apparatus and
accessories have been added. The following are the more important ones:

1. A completely =new stand "A"= with extra fine micrometerscrew
transmitting its movement directly to the tube. The stand is of elegant
appearance and large dimensions, making it especially well adapted for
work in photo-micrography.

2. =Stand I= is now fitted out with the new special fine adjustment (each
division {1/1000} mm).

3. =Stand II= with round centering stage.

4. =Stand IV= is replaced by a model of larger size.

5. =Photo-micrographic apparatus= for use in horizontal and vertical
position, having joint for inclination, large size bellows and
plateholder.

6. =Large projection-apparatus= for electric lamp of 30 Ampère with triple
collecting lens of 210 mm aperture.

7. =Objective 1 a= with adjustable mounting and changeable magnification.
It is an excellent objective of low power for general purposes, having a
comparatively short working distance.

8. =Objective 1 b= with changeable magnification of lowest power, as far
down as two diameters. It serves for drawing extended sections and
specimens.

9. =Saccharimeter after Mitcherlich= improved form.

10. =Trichinoscope=, projection-apparatus of strong and simple
construction.



  =Preface.=


Our American Branch house in New-York under the management of Mr. Wm.
Krafft has now been established for over 10 years. This period has
witnessed a gradual development of our business in the United States,
making it necessary to establish some years ago a Western Branch in
Chicago of which Mr. R. Gibson has charge.

The cordial reception our firm received has been most gratifying and we
take this opportunity to thank our many patrons for their kind
consideration.

It is our aim to co-operate with the scientists and construct new
apparatus to meet their needs or improve others wherever this is
possible.

The foregoing list of additions and improvements made since issueing our
last catalogue is proof that we spare no time nor labor to hold pace
with the increased wants of modern times.

We have now manufactured and sold over 71000 compound microscopes and
31000 oil immersion objectives, a large number of which are used in the
laboratories of Universities, Colleges, and other Educational
Institutions of the United States.

We are prepared at New-York and Chicago to repair our instruments or
make alterations at short notice and at lowest prices. The optical part
of a microscope should invariably be sent to the maker, as he is best in
a position to repair same and has an added interest to bring a lens back
to its original quality or even improve it.

Microscopes, bacteriological apparatus and all other scientific
instruments or preparations expressly imported for use in educational
institutions are exempt from duty.

Catalogues may be had on application by addressing:

  =ERNST LEITZ,=

  NEW-YORK               CHICAGO
  411 West 59th Street   32 Clark, Cor. Lake Street.



  =Objectives and Eye-pieces.=


In the manufacture of our objectives only such glass is employed as has
been subjected to the most rigid scientific tests. By these the exact
index of refraction and the exact degree of dispersion of the glass are
determined, and with these data available it is possible to very
perfectly correct both spherical and chromatic aberrations while still
making use of wide angular apertures in the objectives.

The precise mathematical calculation, combined with accurate
systematical working and testing methods, make it possible for us to
guarantee our objectives to be all of equal and excellent quality.

Every objective before leaving our hands, is subjected to the most
careful test, and only such lenses as are of the highest grade, are sent
out.

For the past seventeen years we have used glasses manufactured by Schott
& Co. of Jena. This glass has many points to recommend it for the
construction of optical instruments, and only such kinds are employed by
us, which have for many years been thoroughly tested as to their
durability.

Our lenses are therefore absolutely permanent. Objectives of the earlier
type which have become cloudy, we shall gladly repair.

[Illustration]

The three illustrations given above afford an idea of the plan of
construction of our achromatic objectives.

The first figure represents the plan of our low power objectives, and it
will be noted that they consist of two doublets, or triplets each
carefully corrected.

The central figure shows the construction of our high power dry
objectives. A hemispherical front lens is combined with two doublets or
sometimes triplets. The front lens is the chief magnifier of the
combination, while the other lenses serve to correct the various
aberrations.

The Oil-immersion, represented by the last illustration consists of a
front lens, hemispherical, behind which is a meniscus, which is in turn
followed by a doublet and a triplet, these latter acting as the
correcting lenses of the combination.

We manufacture both =Achromatic= and =Apochromatic objectives=. They differ
in that the glasses made use of in the apochromatics and the manner in
which they are combined permit a more perfect correction of chromatic
aberration. This advantage is not gained without a certain sacrifice of
simplicity in construction; by avoiding the use of flint glass having a
high refractive index and substituting materials to take the place of
crownglass. The apochromatics as a matter of fact do resolve the fine
markings of test objects (butterfly scales and diatomes) somewhat more
clearly than the achromatics, but the difference is slight and in
ordinary stained microscope preparations is hardly detectable.

The correction of both achromatics and apochromatics is complete. The
ordinary Huyghenian eye-pieces are consequently well adapted for use
with the objectives of either construction. Only with the highest powers
is it desirable to make use of the so-called "compensation" eye-pieces.

The achromatics and Huyghenian eye-pieces are also well adapted to the
requirements of photomicrography, special objectives being unnecessary
for this purpose. This statement is substantiated by the excellent
results obtained with our achromatic objectives, as shown in the
photomicrographs accompanying our brochure on
Photomicrography:--"Anleitung zur Mikrophotographie".

In making use of the higher power objectives--from No. 5 on--it should
be remembered, that the lenses are corrected for cover glasses of 0,17
mm in thickness and for a microscope tube-length of 170 mm. When using
the oil-immersion objectives it is particularly desirable, that this
exact tube length should be employed. With a view to facilitate the
adjustment of the tube-length the draw tubes of all our larger stands
are graduated in millimeters, the scale indicating the exact length of
the microscope tube in any given position of the draw tube. In this
connection it should be remembered, that the width of the collar of the
nose-pieces is 15 millimeters, and that consequently, when a nose-piece
is attached to the tube the reading of the draw tube scale should be 155
mm instead of 170 when the adjustment is proper.

[Illustration: Figure comparative merits of the dry and immersion
systems.]

The above sketch may serve to make clear the advantages of the immersion
objectives over those of the dry series. It is intended to represent
diagrammatically a section through a cover-glass and the front lens of
an objective, one half of the figure representing the conditions present
in the case of the Oil-immersion, the other those which are present in
the dry objectives. It will be noticed that by the interposition of a
drop of oil of the same index of refraction as the glass between the
cover-glass and the objective the refraction which occurs in the dry
system when the light leaves the upper surface of the cover-glass is
done away with. Since this second refraction is attended with much loss
of light it must be evident, that in the immersion system a much greater
quantity of light enters the objective than is possible, other things
being equal, in objectives of the dry system.

If we let _u_ represent one half the angular aperture of an objective,
represented in the diagram by _D'BN_ in the case of the immersion, and
_n_ the index of refraction of the medium interposed between the
cover-glass and the objective we have in the formula _n_ sin. _u_ a
mathematical expression of the optic power of the various systems of
lenses, or in other words for what is designated the numerical aperture.

The following table gives the numerical apertures of objectives of the
various systems and of various angular apertures. In the dry system
_n._, representing the index of refraction of air is taken as 1.00; in
the immersion systems _n_ equals 1.33 for water, 1.52 for cedar oil and
1.66 for monobromnaphthalin. A glance at the table will suffice to show
the great advantage which the immersion objectives have over those of
the dry series.

  --------------+----+----+----+----+----+----+----+----+----+----+----+----+----+----
  Angular       |10° |20° |30° |40° |50° |60° |70° |80° |90° |100°|110°|120°|130°|140°
  aperture 2 _u_|    |    |    |    |    |    |    |    |    |    |    |    |    |

  =Numerical apertures.=

  --------------+----+----+----+----+----+----+----+----+----+----+----+----+----+----
  Dry series    |0,09|0,18|0,26|0,34|0,42|0,50|0,57|0,64|0,71|0,77|0,82|0,87|0,91|0,94
  _n_ = 1,00    |    |    |    |    |    |    |    |    |    |    |    |    |    |
  --------------+----+----+----+----+----+----+----+----+----+----+----+----+----+----
  Water-        |    |    |    |    |    |    |    |    |    |    |    |    |    |
  Immersion     |0,12|0,24|0,35|0,46|0,56|0,66|0,76|0,85|0,94|1,02|1,09|1,15|1,20|1,25
  _n_ = 1,33    |    |    |    |    |    |    |    |    |    |    |    |    |    |
  --------------+----+----+----+----+----+----+----+----+----+----+----+----+----+----
  Homogeneous   |    |    |    |    |    |    |    |    |    |    |    |    |    |
  Oil-Immersion |0,14|0,26|0,40|0,52|0,64|0,76|0,87|0,98|1,07|1,16|1,24|1,32|1,38|1,43
  _n_ = 1,52    |    |    |    |    |    |    |    |    |    |    |    |    |    |
  --------------+----+----+----+----+----+----+----+----+----+----+----+----+----+----
  Monobromide of|    |    |    |    |    |    |    |    |    |    |    |    |    |
  Naphthaline-  |    |    |    |    |    |    |    |    |    |    |    |    |    |
  Immersion     |0,15|0,29|0,43|0,57|0,70|0,83|0,95|1,07|1,17|1,27|1,36|1,44|1,50|1,56
  _n_ = 1,66    |    |    |    |    |    |    |    |    |    |    |    |    |    |

[Illustration: Photographic objectives with iris diaphragms, f/3.5]

  ----------------+----+----+----+----
  Focal length mm | 64 | 42 | 35 | 24
  ----------------+----+----+----+----
  Price $         | 20 | 18 | 18 | 18
  ----------------+----+----+----+----



  =Objective 1b.=


It is designed principally for drawing extended sections and large
specimens, and consists of two adjustable doublets. By varying their
distance, a changeable magnification down to two diameters may be
obtained.

  Price $ 8.--


  =Huyghenian Eye-pieces.=
  ----------------+------+------+------+-------+------+------
        Number    |  0   |  I   |  II  |  III  |  IV  |  V
  ----------------+------+------+----------------------------
  Focal length mm |  50  |  40  |  35  |   30  |  25  |  20
  ----------------+------+------+----------------------------
          Price of each eyepiece $ 2.00.


The objectives designed for the Edinger apparatus of 64, 42, 35, and 24
mm focal distance have been found to be very useful for a number of
purposes and have come into great favor.

(see. Dr. Kaiserling: Praktikum der wissenschaftlichen Photographie p.
263).



  =Achromatic Objectives.=

  =============================================================================
                  |              |Numerical   |  Micrometer    | Price
  No. of Objective|Focal length  |Aperture    |    Values      |   $
                  |              |(num. aper.)|                |
  ————————————————+——————————————+————————————+————————————————+———————————————
  Low power   { 1*|44 mm (1-3/4")|    0,09    | 0,054 mm = 54µ |  =3.25=[1]
    Dry       { 1 |44 mm (1-3/4")|    0,09    | 0,054 mm = 54µ |  =6=
    Series    { 1a| 39-27 mm     | 0,06--0,10 |    50--26µ     | =10= (adjustable
                  |              |            |                |       mounting)
              { 2 |30 mm (1-1/4")|    0,14    | 0,028 mm = 28µ |  =6=
              { 3 |18 mm (3/4)   |    0,28    | 0,015 mm = 16µ |  =6=
              { 4 | 8 mm (1/3)   |    0,55    | 0,009 mm =  9µ | =10=
          ————————+——————————————+————————————+————————————————+———————————————
  High power  { 5 |5,8 mm (1/4") |    0,77    |0,0045 mm = 4,5µ| =10=
              { 6 |4,4 mm (1/6") |    0,82    |0,0034 mm = 3,5µ| =12=
  (Fluorite)  { 6a|4,4 mm (1/6") |    0,82    |0,0034 mm = 3,5µ| =16=[2]
              { 7 |3,2 mm (1/8") |    0,85    |0,0026 mm = 2,6µ| =12=
  (Fluorite)  { 7a|3,2 mm (1/8") |    0,85    |0,0026 mm = 2,6µ| =16=[2]
        "     { 8 |2,5 mm (1/10")|    0,87    |0,0020 mm = 2,0µ| =16=
        "     { 9 |2,2 mm (1/12")|    0,87    |0,0017 mm = 1,7µ| =24=
          ————————+——————————————+————————————+————————————————+———————————————
  Water-          |              |            |                |
     Immersion  10|2,2 mm (1/12")|    1,10    |0,0017 mm = 1,7µ| =26=
          ————————+——————————————+————————————+————————————————+———————————————
  Homogeneous{1/10|2,5 mm (1/10")|    1,30    |0,0022 mm = 2,2µ| =30=
   Oil-      {1/12|2,1 mm (1/12")|    1,30    |0,0017 mm = 1,7µ| =40=
   Immersion {1/16|1,7 mm (1/16")|    1,30    |0,0014 mm = 1,4µ| =60=
  =============================================================================

[Footnote 1: Objective 1* consists of only one doublet, carefully
corrected. It is sufficient for many purposes, though it does not
possess the same brilliancy of field as the No. 1 objective.]

[Footnote 2: The objectives 6a. and 7a. are better corrected in
achromatism than the regular No. 6 and 7.]



  =Magnification=
  of the Achromatic and Apochromatic Objectives in combination with the
  Huyghenian Eye-pieces.

  Tube-length 170 mm. Distance of image 250 mm.

  ============================================================================
                           |          Eye-pieces               |
         Objectives        |-----------------------------------| Objectives
                           |  0  |  I  | II  | III |  IV |  V  |
  —————————————————————————+—————+—————+—————+—————+—————+—————+——————————————
                      { 1* |  12 |  18 |  22 |  26 |  30 |  40 |
                      { 1  |  12 |  18 |  22 |  26 |  30 |  40 |
  Low Power           { 1a | 6-9 | 9-15|11-19|13-21|18-29|24-35|
    Objectives        { 2  |  25 |  33 |  40 |  50 |  60 |  80 |
                      { 3  |  45 |  60 |  70 |  80 | 105 | 130 |
                      { 4  |  75 | 100 | 115 | 135 | 180 | 230 |
  —————————————————————————+—————+—————+—————+—————+—————+—————|
  High Power     {    5    | 140 | 180 | 210 | 250 | 325 | 420 |
    Objectives   { 6 and 6a| 200 | 255 | 300 | 350 | 460 | 600 |  Achromatics
   (Cover-glass  { 7 and 7a| 260 | 335 | 400 | 450 | 600 | 780 |
    thickness    {    8    | 300 | 400 | 450 | 550 | 700 | 940 |
    0,17 mm)     {    9    | 380 | 500 | 575 | 700 | 900 |1150 |
  —————————————————————————+—————+—————+—————+—————+—————+—————|
  Water-Immersion  { 10    | 405 | 535 | 610 | 745 | 950 |1200 |
  —————————————————————————+—————+—————+—————+—————+—————+—————|
  Homogeneous      { 1/10  | 310 | 415 | 470 | 575 | 730 | 940 |
  Oil-Immersion    { 1/12  | 435 | 555 | 650 | 800 |1000 |1300 |
                   { 1/16  | 520 | 700 | 800 | 950 |1250 |1680 |
  —————————————————————————+—————+—————+—————+—————+—————+—————+——————————————
  Dry              { 16    |  45 |  60 |  70 |  85 | 110 | 140 |
  Lenses           {  8    |  95 | 125 | 145 | 170 | 225 | 295 | Apochromatics
                   {  4    | 210 | 270 | 315 | 375 | 500 | 635 |
  —————————————————————————+—————+—————+—————+—————+—————+—————|
  Oil-Immersion       2    | 390 | 510 | 585 | 705 | 920 |1180 |
  ============================================================================



  =Apochromatic Objectives.=

  ==================================================================
    Objectives           |Focal length|Numerical|Micrometer| Price
                         |    mm      | Aperture|  Values  |   $
  ———————————————————————+————————————+—————————+——————————+————————
                    { 16 |    16      |   0,30  | 0,015 mm |  =24=
   Dry Series       { 8  |     8      |   0,65  | 0,007 mm |  =32=
                    { 4  |     4      |   0,95  | 0,003 mm |  =48=
                         |            |         |          |with correction
                         |            |         |          |  collar
  ———————————————————————+————————————+—————————+——————————+————————
  Homogeneous       { 2  |     2      |   1,30  | 0,002 mm | =100=
  Oil-Immersion     {    |            |         |          |
  ———————————————————————+————————————+—————————+——————————+————————


  Compensation Eye-pieces.
  for Apochromatic Objectives.

  =================================================
  Eye-pieces    |   4  |   6  |   8  |  12  |  18
  --------------+------+------+------+------+------
  Price       $ |=6.50=|=6.50=| =10= | =10= |  =8=
  =================================================
    Compensation Eye-piece 6 with micrometer =$8.50=


  =Magnification=
  of the Apochromatic Objectives in combination with the Compensation
  Eye-pieces.

  ==================================================
                      |         Eye-pieces
    Objectives        |-----+-----+-----+-----+-----
                      |  4  |  6  |  8  | 12  | 18
  --------------------+-----+-----+-----+-----+-----
                 { 16 |  70 | 100 | 125 | 155 | 225
    Dry Series   {  8 | 140 | 200 | 260 | 325 | 465
                 {  4 | 300 | 430 | 550 | 675 |1000
  --------------------+-----+-----+-----+-----+-----
  Oil-Immersion     2 | 575 | 820 |1080 |1500 |2250
  ==================================================

[Illustration: Double revolving Eye-piece.]

Until very recently we have manufactured no arrangement for changing
oculars on the microscope. This was due in part to the fact that there
was no great demand for such an accessory and in part to the clumsiness
of all those revolving eye-pieces which changed the entire ocular. The
latter of these difficulties has been overcome in our present revolving
eye-piece by such an adjustment of the collecting or lower lens of the
eye-piece that it may remain permanently in position, the eye lens of
the combination alone moving in the revolver. So accurate is the
construction of the revolver and so carefully are the lenses adjusted
that the eye-pieces may be changed while a specimen is in focus on the
microscope stage without a readjustment of the focus.

The revolving eye-piece is also particularly well adapted to use as a
micrometer ocular, for when the eye lens is turned aside a micrometer
scale may be inserted and rests upon the diaphragm of the eye-piece.
Once adjusted in this way the micrometer values are the same for all the
eye lenses of the combination.

                                                                $
  Prices: =Double revolving Eye-piece=, without eye lenses    =4.--=
           Each eye lens                                      =1.25=
          =Eye-piece Micrometer=, No. 86                      =2.--=



  =Stands.=


For the past thirty years division of labor has been employed to the
utmost possible extent in the manufacture of our microscopes. This
principle has been applied to our machinery as well as to our workmen,
with the result that we have gradually accumulated a large plant of
special machinery of the most accurate construction, each machine
especially adapted to the manufacture of some particular part of our
microscopes. By this development of mechanical appliances for microscope
manufacture two ends have been attained:--The greatest accuracy and
uniformity of construction of our microscopes has been made possible,
while at the same time it has been possible to cheapen the cost of
manufacture. Instruments which are the product of delicate machinery
must always be more uniform, more accurate and should be less costly
than those manufactured by hand.

In the following remarks we refer more particularly to the larger
microscope stands of our manufacture and draw attention to those
parts which should be present in every well equipped microscope.

The elements of these microscopes are:

    1. =The foot and upright support with joint for inclination=,
    2. =The stage=,
    3. =The sub-stage, with condenser, iris diaphragm and mirror=,
    4. =The body with the adjustments=,
    5. =The tube, carrying eye-piece, nose-piece and objectives=.

1. =The foot and upright support= are solid and are of such weight and
shape as to permit inclination of the body of the microscope to a
horizontal position. The foot is horse-shoe shaped and is made to touch
the table at three points, thus insuring stability even on a surface
which is not entirely level. Inclination of the body of the microscope
is permitted by a joint in the upright, which joint may be fastened in
the larger stands by a set-screw operated by a lever. Stands Ia and IIb
are also made with the English foot. Abundant space is left under the
stage for the various attachments of the sub-stage.

2. =The stage= of Stands A, I, Ia and II is round, revolving and
centering. The centering arrangement consists of two small thumb-screws
so situated at the sides of the stage as to control motion of the stage
in all directions, thus to a limited extent serving the purpose of a
mechanical stage.

=The other microscope= stands have square immovable stages, sufficiently
large for general microscopic work. For the examination of very large
sections two instruments are manufactured: the _Nebelthau_ sliding
microscope (p. 50) and the stand after _Dölken_ (p. 52). The former is
for magnifications up to 120 diam, whereas the latter can be used with
any magnification.

3. =The sub-stage= carries a plane and concave mirror, the condenser and
the diaphragm for regulating the illumination of the object.

=The Condenser= is so adjusted as to concentrate the rays of light about 2
mm above its surface, which is the average thickness of the microscopic
slides, under an angle equal to the angular aperture of the highest
power objective, which is about 120°.

In the lower power objectives the angular aperture is to be reduced by
the iris diaphragm.

To focus the Condenser properly it is adjustable by rack and pinion
movement on Stands A, I, Ia, Ib, and by side screw on Stands II and IIa.

4. =The body= of the microscope carries the tube and is fitted with two
adjustments for focussing; a coarse adjustment and a fine adjustment.
The smooth working of these adjustments is one of the chief requirements
of a good microscope.

=The coarse adjustment= consists of rack and pinion and moves the tube of
the microscope in a vertical groove with the least possible friction.
The teeth of the rack and pinion are set obliquely to the axis of the
tube and are so adjusted that two teeth of each are always interlocked,
thus avoiding all possibility of slipping or loss of motion in the
movement.

[Illustration: Figure of the Micrometer-screw of the fine adjustment.]

=The fine adjustment= consists of a micrometer screw which moves the tube
and arm of the microscope supporting the coarse adjustment vertically
upon a triangular column. This column is virtually a continuation upward
of the upright support of the base of the microscope. Around the column
is a broad collar so accurately fitted that it moves smoothly upon it
with a minimum of friction and still without lateral motion, the
movement being controlled by means of a micrometer screw at the top of
the column. The head of this micrometer screw, a section of which is
shown in the accompanying figure, is milled and is graduated in such a
way as to indicate the exact degree of motion of the microscope tube
which is accomplished by turning the micrometer screw, each division of
the graduation corresponding to a motion of the tube through 1/100
millimeter, and a complete revolution of the screw corresponding to a
motion of the tube through ½ millimeter. The accuracy of this adjustment
and the smoothness of its motion must be conceded to be a triumph of
mechanical skill.

=Stands A.= and =I.= are fitted with a =new fine adjustment= device (one
division on the micrometer screw corresponding to 1/1000 mm.) which is
fully described on pages 25-26.

5. =The tube= of the microscope encloses a second tube, or draw-tube,
which latter carries the eye-piece, and is so graduated as to indicate
the exact length of tube in use at any time. The lower end of the tube
has a thread into which the various objectives or a nose-piece screw.
Tube and objectives are provided with the so-called "Society screw".

=The nose-piece= has now become an almost indispensable part of a working
microscope. It can, however, be used to best advantage only on such
stands as are provided with a coarse adjustment by rack and pinion.
Aside from the advantage derived from the rapid changing of objectives,
which it permits, it is so accurately made and centered as to materially
facilitate the focussing of the various objectives. It is only necessary
to focus with the fine adjustment to obtain a view of the same
microscope field which had been under observation before the change was
made.

As it is necessary for this purpose that the objectives should be
accurately adjusted to the nose-piece, it is very desirable that in
ordering an instrument its nose-piece should be ordered at the same time
if one is to be used, as subsequent ordering may necessitate the return
of the stand and objectives to us.

=Stands A, I, Ia, Ib, II, IIa, IIb and III= are those which are best
suited to fine microscopical investigations. Among them the physician
and bacteriologist will find an instrument entirely suited to his
particular needs.

=Stand III= is now provided with rack and pinion adjustment.

=Stands IV and V= are small instruments, which serve nevertheless many
purposes where the more elaborate outfits are unnecessary. They make
excellent laboratory stands for elementary courses in microscopy.

In =Stands IV and V= the coarse adjustment is by means of sliding tube.
They are all provided with fine adjustment by micrometer screw.

=Stand VI= is provided with rack and pinion adjustment only. It has a
large stage, and is particularly intended for searching for trichinae
and for similar examinations where a very strong durable stand is
desired and where the use of high power objectives is unnecessary. It
may also be useful as an auxiliary stand for purposes of demonstration
in laboratories.

=Stands III, IV, V, VI= have no joint for inclining the body.

=Stands A, I, Ia, Ib, II, IIa, IIb, III, IV= have mahogany cases (provided
with a nickelled handle), in which the microscopes stand.

=Stands V and VI= are laid in mahogany boxes.

These cases are furnished with the microscopes without extra charge,
when a =complete outfit=, including oculars and objectives is purchased.

Object clamps and test objects accompany every microscope.

The objectives to Stands A, I, Ia, Ib, II, IIa, IIb are in brass boxes;
those for Stands III, IV, V and VI are in morocco cases.



  =Illuminating Apparatus.=


  =a. Illuminating Apparatus of Stands A and I.=

The apparatus includes the following parts:

    Cylinder iris diaphragm.
    Swing-out condenser.
    Diaphragm carrier with iris diaphragm.
    Plane and concave mirror.

The cylinder iris diaphragm comes into play when the condenser
is swung out of position. To do this the diaphragm carrier is
turned to the side as shown in the diagram, a small knob is
pressed, which liberates the condenser, and the latter is
swung out to the side.

The regulation of the cylinder iris diaphragm is accomplished
by means of a lever. Before the condenser is swung back into
position the cylinder iris should be opened to its fullest
extent. The lower iris diaphragm is for use in connection with
the condenser only. It is regulated by means of a small knob.
A horizontal rack and pinion arrangement permits oblique
illumination, and a vertical rack and pinion permits
adjustment of the whole sub-stage. By these means a most
perfect control of the illumination of the object is assured.
Ground or colored glass discs may be inserted above the iris
diaphragm if modification of the light is desired.             =$30.--=

_This illuminating apparatus may also be fitted to Stands Ia and Ib._

[Illustration: Abbe's Illuminating Apparatus for Stand A and I.

Swing-out Condenser.

Cylinder Iris Diaphragm.]

  =b. Illuminating Apparatus of Stands Ia and Ib= (p. 30, 32, 34).

[Illustration]

The following are the parts of this apparatus:

    Cylinder diaphragm with 3 stops of different apertures.
    Condenser.
    Diaphragm carrier with iris diaphragm.
    Plane and concave mirror.

To substitute the condenser for the cylinder diaphragm the
diaphragm carrier is turned to the side and the cylinder
diaphragm is drawn out of the sleeve which holds it in
position and into which the condenser readily fits. The
diaphragm carrier is then turned back into position and the
amount of light regulated by manipulating the knob controlling
the size of the iris. The whole sub-stage may be raised or
lowered in the optical axis by means of a rack and pinion, and
a similar arrangement permits lateral illumination by moving
the iris diaphragm in the horizontal plane.

Ground glass and colored plates may be inserted above the iris
diaphragm.                                                     =$24.--=


  =c. Illuminating Apparatus for Stand II and IIa= (p. 36 & 38).

The condenser and iris diaphragm form one piece, giving
central but no oblique illumination. The whole apparatus may
be raised and lowered in the optical axis by means of a screw.
The cylinder diaphragm may be inserted in place of the
condenser. A ring below the iris diaphragm permits the
insertion of glass discs for the purpose of modifying the
light.                                                         =$12.--=


  =d. Illuminating apparatus for Stand IIb= (p. 40).

The same as for II and IIa fitted in a fixed sleeve; without
the side-screw.                                                =$10.--=

  =e. Small Illuminating Apparatus.=

[Illustration: Small Illuminating Apparatus.]

The small illuminating apparatus consists of a somewhat
smaller condenser with iris diaphragm and can be adjusted to
the Stand IV, when it has the cylinder diaphragm.               =$8.--=

[Illustration: Cylinder iris diaphragm.]

A cylinder iris diaphragm can be furnished in place of the
ordinary cylinder diaphragm of Stand II, IIa and IIb at an
additional cost of                                              =$6.--=

[Illustration: Iris diaphragm fitted to stage of stand III.]

Stand III can be had with iris diaphragm fitted in stage, in
place of the wheel diaphragm (see page 43) Additional price     =$6.--=


=_Complete Microscope Outfits._=

The outfits comprised in the following pages are made up with achromatic
objectives, which suffice for all ordinary needs.

We are glad to supply any other combination of eye-pieces and objectives
which may be preferred. The price of each outfit may be readily computed
by adding together the cost of its various items.

Microscope =stands=, without objectives, will not be sold separately.

[Illustration: Stand A.--Universal Microscope.]


  =Stand "A".=

  Universal Microscope.

In the construction of our new stand "A" we have taken special care to
enlarge all the parts proportionately in order to secure strength and
stability, at the same time adding to the beauty of the instrument.

The upper pillar of the microscope is shaped in such a way as to form a
convenient handle; and to increase the free working space over the
stage, thereby allowing the examination of very large specimen and
culture plates. A specially constructed mechanical stage larger than No.
98 may be attached, which is adapted for slides up to 2×4 inches (50×100
mm).

The extra large dimensions of all the main parts of this microscope such
as the base and stage etc., allow that freedom of movement so desired in
a stand for photo-micrography.

Both the body tube and graduated draw tube are very wide and permit the
use of low power objectives to cover specimen of large extent; for the
same reason the opening in the stage is very wide but can be narrowed
down by a stop.

The most important innovation on the microscope is the new fine
adjustment device, which is unexcelled both in solidity of construction
and accuracy of movement, representing the highest attainment of the
designers and mechanics skill.

Sectional cuts of this unique arrangement are shown in illustration (p.
26-27).

All that can be seen on the exterior are two small milled heads mounted
below and somewhat back of the two larger knobs controlling the rack and
pinion (coarse) adjustment of the microscope. The knob on the right side
is provided with a graduated drum _r_, indicating the movement of the
fine adjustment.

The two knobs with drum are mounted on an axle _a_, which in its central
portion is enlarged and provided with a worm gear. The latter in its
turn drives the gear wheel, _d_. A spiral spring pressing against one of
the journals into which the axle is mounted prevents any lost motion in
the worm gear. Mounted on the same shaft with the gear-wheel _d_, is a
heartshaped cam _f_. On this cam rests the steel roller _g_, fitted on
the support _k_, which in its turn carries the microscope tube. By its
weight and a spiral spring the latter presses on the cam _f_, and
effects a direct vertical movement.

[Illustration]

The periphery of the heart shaped cam _f_, is exactly symmetrical and
mathematically correct. The distance traversed by its curved sides from
the lowest to the highest point and vice versa is 3 mm. There are cut 60
teeth in the entire periphery of the gear-wheel _d_; the number
corresponding to one side of the heart-shaped cam or 3 mm elevation, are
30 teeth, therefore 1 tooth means a movement of 3/30 mm or 0,1 mm.

This in turn requires one complete revolution of the axle _a_, the drum
of which is graduated into 100 parts. The value of each division on the
drum is therefore 0,1/100=0,001 mm.

This micrometer fine adjustment is exceedingly accurate and reliable,
and besides it has the following advantages;

By virtue of its unique construction the movement is continuous, there
is absolutely no limit to the motion of the micrometer screw, which may
be turned forward or backward as the work requires.

This movement extends in exact ratio to the revolution of the cam for a
distance of 3 mm. As another advantage we may mention, that it is almost
impossible to break the coverglass of the specimen with this fine
adjustment.

Should the objective come in contact with the coverglass and assuming
the knob is turned still further then the tube, which is of aluminium
and very light would simply rest on the specimen, without breaking the
coverglass, as the latter will easily stand the small pressure of the
tube and the fine spiral spring.

[Illustration]

No.                                                                $

   1. New microscope stand "A" inclinable with hinged joint
      and clamping lever, fitted with round revolving
      centering stage, coarse adjustment by rack and pinion,
      new fine adjustment by micrometer-screw (each division
      1/1000 mm.) Wide tube, draw tube with millimeter scale.
      Large illuminating apparatus with swing-out condenser
      and cylinder-iris diaphragm                              =120.--=
        Apochr. 16, 8, 4, oil-imm. 2 mm. N. A. 1,30            =204.--=
        Compens. ocular 4, 8, 12, 18                            =34.50=
        Compens. ocular No. 6 with micrometer and drawing
          ocular No. 93                                         =18.50=
        Large mechanical stage No. 99, for object slides
          up to 2×4 inches                                      =32.--=
        Triple nose-piece                                        =8.--=
                                                                ——————
           Magnif. 70—2250.                                    =417.--=

   2. The same stand and illum. apparatus;
      Object.: 2, 4, 6, oil-imm. 1/12, N. A. 1,30
      Ocul. 0. I. III. IV. V. microm. ocul. II.
      Triple nosepiece                                         =210.--=

[Illustration: Stand I.]

  Stand I.

   3. =Large microscope=, inclinable, with hinged joint and
      clamping lever and fitted with round revolving centering
      stage. Coarse adjustment by rack and pinion, new fine
      adjustment by micrometer-screw, the head of which is
      graduated each division = 1/1000 mm. Draw-tube with (see
      page 25-26) millimetre scale. Large illuminating
      apparatus with swing-out condenser and cylinder iris
      diaphragm (illustrated on page 21).
        Mechanical stage, No. 98.
        Triple nose-piece.
        Drawing eye-piece, No. 93.
        Micrometer eye-piece, No. 84.
        Achromatic objectives Nos. 1, 3, 6.
        Oil-Immersion 1/12, N. A. 1,30.
        Eye-pieces 0, I, III, IV, V.
        Magnifications 12—1300                                 =236.--=

   4. =The same= stand and illuminating apparatus.
        Triple nose-piece.
        Micrometer eye-piece, No. 84.
        Drawing eye-piece, No. 93.
        Objectives 2, 4, 6, Oil-Immersion 1/12, N. A. 1,30.
        Eye-pieces I, III, IV, V.
        Magnifications 33-1300                                 =210.--=

=The stand= and illuminating apparatus without objectives,
oculars and nose-piece                                         =112.--=

[Illustration: Stand Ia.]

  =Stand Ia.=

  4a. =Large Microscope=, of smaller size than Stand I,
      fitted with horseshoe foot. The stand is inclinable and
      fitted with revolving centering stage, coarse adjustment
      by rack and pinion, fine adjustment by micrometer screw
      with scale. Draw-tube with millimetre scale. Large
      Illuminating Apparatus (Cf. p. 22, b) with rack and
      pinion, and iris-diaphragm with oblique movement. The
      cylinder-diaphragm and condenser may be readily
      substituted for one another.
        Triple nose-piece.
        Objectives 2, 4, 6, Oil-Immersion 1/12, N. A. 1,30.
        Eye-pieces I, III, IV, V.
        Magnifications 33-1300                                 =160.--=

  4b. =The same= with Illuminating Apparatus.
        Triple nose-piece.
        Objectives 3, 6, Oil-Immersion 1/12, N. A. 1,30.
        Eye-pieces I, III, IV.
        Magnifications 60-1000                                 =148.--=

  4c. =The same= with Illuminating Apparatus.
        Triple nose-piece.
        Objectives 3, 6, Oil-Immersion 1/10, N. A. 1,30.
        Eye-pieces II and IV.
        Magnifications 70-730                                  =136.--=

      =Stand= with Illuminating Apparatus, but without
      objectives, eye-pieces and nose-piece                     =76.--=

      =The same= with Illuminating Apparatus, Swing-out
      Condenser and Cylinder Iris-diaphragm (p. 20, a)          =82.--=

      Mechanical stage No. 98 can be fitted to this stand;
      price                                                     =28.--=

[Illustration: Stand Ia with English foot.]

  =Stand Ia=
  with English foot.

  4d. =Large Microscope= differing from the foregoing (Ia)
      stand only in being provided with an English foot, which
      makes the stand somewhat steadier and lighter. The
      prices and combinations are otherwise the same.

      Dr. P. G. Unna of Hamburg uses this microscope in his
      laboratory.

      The stage revolves and centres. The illuminating
      apparatus is that described on p. 22, b.
        Triple nose-piece.
        Objectives 2, 4, 6, Oil-Immersion 1/12, N. A. 1,30.
        Eye-pieces I, III, IV, V.
        Magnifications 33—1300                                 =160.--=

  4e. =The same= with the illuminating apparatus.
        Triple nose-piece.
        Objectives 3, 6, Oil-Immersion 1/12, N. A. 1,30.
        Eye-pieces I, III, IV.
        Magnifications 60—1000                                 =148.--=

  4f. =The same= with illuminating apparatus.
        Triple nose-piece.
        Objectives 3, 6, Oil-Immersion 1/10, N. A. 1,30.
        Eye-pieces II, IV.
        Magnifications 70—730                                  =136.--=

      =The stand= with illuminating apparatus, but without
      objectives, oculars and nose-piece                        =76.--=

      =The stand= with swing-out condenser (p. 20, a)           =82.--=

      Mechanical stage No. 98 can be fitted to this
      stand; price                                              =28.--=

[Illustration: Stand Ib.]

  =Stand Ib.=

   5. =Large Microscope=, which differs from Ia only in the
      stage. The stage is fixed and square. The stand is
      inclinable and has a hinged joint and clamping lever.
      Draw-tube with millimetre scale. Coarse adjustment by
      rack and pinion, fine adjustment by micrometer screw
      with graduated head. Illuminating Apparatus, same as Ia
      (p. 22, b).
        Triple nose-piece.
        Objectives 3, 6, Oil-Immersion 1/12, N. A. 1,30.
        Eye-pieces I, III, IV.
        Magnifications 60—1000                                 =142.--=

   6. =The same= with simplified Illuminating Apparatus (p. 22, c).
        Triple nose-piece.
        Objectives 3, 6, Oil-Immersion 1/10, N. A. 1,30.
        Eye-pieces I, III, IV.
        Magnifications 60—730                                  =120.--=

   7. =The same= without Illuminating Apparatus, with Cylinder-diaphragm.
        Double nose-piece.
        Objectives 3, 7.
        Eye-pieces I, III.
        Magnifications 60—450                                   =74.--=

   8. =The same= without Illuminating Apparatus and without
      nose-piece.
        Objectives 3, 7.
        Eye-pieces I, III.
        Magnifications 60—450                                   =68.--=

      =Stand= without objectives and eye-pieces, without
      illuminating apparatus and without nose-piece             =46.--=

      =Stand= without objectives and eye-pieces, with
      illuminating apparatus, without nose-piece                =70.--=

      =The same= with illuminating apparatus, with swing-out
      condenser and cylinder iris-diaphragm (p. 22 a)           =76.--=

[Illustration: Stand II.]

  =Stand II.=

  9a. =Medium Size Microscope=, inclinable, with revolving
      centering vulcanite stage, coarse adjustment by rack and
      pinion, fine adjustment by micrometer-screw. Draw-tube
      with millimetre scale. Illuminating apparatus and iris-
      diaphragm with lateral screw for raising and lowering.
      A ring under the iris diaphragm serves to hold a ground
      glass or colored disc. The illuminating apparatus and
      cylinder diaphragm are easily interchangeable.
        Triple nose-piece.
        Objectives 3, 6, Oil-Immersion 1/12, N. A. 1,30.
        Eye-pieces I, III, IV.
        Magnifications 60—1000                                 =126.--=

  9b. =The same= with Illuminating Apparatus.
        Triple nose-piece.
        Objectives 3, 6, Oil-Immersion 1/10, N. A. 1,30.
        Eye-pieces II, IV.
        Magnifications 70—730                                  =114.--=

  9c. =The same= without Illuminating Apparatus.
        Triple nose-piece.
        Objectives 3, 6, 8.
        Eye-pieces I, III.
        Magnifications 60—550                                   =90.--=

  9d. =The same= without Illuminating Apparatus.
        Double nose-piece.
        Objectives 3, 7.
        Eye-pieces I, III.
        Magnifications 60—450                                   =72.--=

  9e. =The same= without Illuminating Apparatus and nose-piece.
        Objectives 3, 7.
        Eye-pieces I, III.
        Magnifications 60—450                                   =66.--=

      =Stand= with Illuminating Apparatus and Iris-diaphragm,
      without objectives, eye-pieces and nose-piece.            =54.--=

      =The same stand= with Cylinder Diaphragm                  =44.--=

      =Stand= with illuminating apparatus, swing-out condenser
      and cylinder iris diaphragm                               =60.--=

      =Cylinder iris diaphragm= (Cf. p. 23)                      =6.--=

[Illustration: Stand IIa.]

  =Stand IIa.=

  9. =Medium Size Microscope=, inclinable, coarse adjustment
      by rack and pinion, fine adjustment by micrometer-screw.
      Draw-tube with millimetre scale. Illuminating apparatus
      and iris-diaphragm with lateral screw for raising and
      lowering. A ring under the iris diaphragm serves to
      hold a ground glass or colored disc. The illuminating
      apparatus and cylinder diaphragm are easily interchangeable.
        Triple nose-piece.
        Objectives 3, 6, Oil-Immersion 1/12, N. A. 1,30.
        Eye-pieces I, III, IV.
        Magnifications 60—1000                                 =120.--=

  10. =The same= with Illuminating Apparatus.
        Triple nose-piece.
        Objectives 3, 6, Oil-Immersion 1/10, N. A. 1,30.
        Eye-pieces II, IV.
        Magnifications 70—730                                  =108.--=

  11. =The same= without Illuminating-Apparatus.
        Triple nose-piece.
        Objectives 3, 6, 8.
        Eye-pieces I, III.
        Magnifications 60—550                                   =84.--=

  12. =The same= without Illuminating Apparatus.
        Double nose-piece.
        Objectives 3, 7.
        Eye-pieces I, III.
        Magnifications 60—450                                   =66.--=

  13. =The same= without Illuminating Apparatus and nose-piece.
        Objectives 3, 7.
        Eye-pieces I, III.
        Magnifications 60—450                                   =60.--=

      =Stand= with Illuminating Apparatus and Iris-diaphragm,
      without objectives, eye-pieces and nose-piece             =48.--=

      =The same stand= with Cylinder Diaphragm                  =38.--=

      =Cylinder iris-diaphragm= (Cf. p. 23)                      =6.--=

[Illustration: Stand IIb.]

  =Stand IIb.=

 14a. =Medium Size Microscope=, stand inclinable to the extent
      of 45°, tripod foot, coarse adjustment by rack and
      pinion, fine adjustment by micrometer screw. Draw-tube
      with millimetre scale. Illuminating Apparatus and
      Iris-diaphragm permanently connected and sliding in a
      sleeve underneath the stage. The cylinder-diaphragm
      is used in the same manner. A ring below the iris-diaphragm
      serves to hold a ground glass or colored disc.
        Triple nose-piece.
        Objectives 3, 6, Oil-Immersion 1/12, N. A. 1,30.
        Eye-pieces I, III, IV.
        Magnifications 60—1000                                 =104.--=

 14b. =The same= with Illuminating Apparatus.
        Triple nose-piece.
        Objectives 3, 6, 8.
        Eye-pieces II, IV.
        Magnifications 70—700                                   =78.--=

 15a. =The same= without Illuminating Apparatus.
        Double nose-piece.
        Objectives 3, 7.
        Eye-pieces I, III.
        Magnifications 60—450                                   =50.--=

 15b. =The same= without Illuminating Apparatus and nose-piece.
        Objectives 3, 7.
        Eye-pieces I, III.
        Magnifications 85—450                                   =44.--=

      =Stand= with Illuminating Apparatus and Iris-diaphragm    =32.--=

      =Stand= with Cylinder or Wheel-diaphragm                  =22.--=

      =Cylinder iris-diaphragm= (p. 23)                          =6.--=

      For the addition to this microscope of a lateral screw
      for raising and lowering the illuminating apparatus as
      on Stand IIa, an extra charge of $2.-- is made.

[Illustration: Stand III.]

  =Stand III.=

Stand III is now provided with rack and pinion coarse adjustment instead
of sliding tube. In consequence a nose-piece can be used on it to better
advantage. It will be found an excellent laboratory stand at low price.

 16a. =Medium Size Microscope=, non-inclinable stand,
      coarse adjustment by rack and pinion, fine adjustment by
      micrometer-screw. The draw-tube has a millimetre scale.
      Plane and concave mirror. Wheel-diaphragm.
        Triple nose-piece.
        Objectives 3, 6, 8.
        Eye-pieces I, III.
        Magnifications 60—550                                   =66.--=

 16b. =The same= without nose-piece.
        Objectives 3, 6, 8.
        Eye-pieces I, III.
        Magnifications 60—550                                   =58.--=

 17a. =The same=, with double nose-piece.
        Objectives 3, 7.
        Eye-pieces I, III.
        Magnifications 60—450                                   =48.--=

 17b. =The same= without nose-piece.
        Objectives 3, 7.
        Eye-pieces I, III.
        Magnifications 60—450                                   =42.--=

      =Stand= with wheel-diaphragm                              =20.--=

      =This stand= can be supplied with iris diaphragm in
      stage (see illustration p. 23) instead of
      wheel-diaphragm.

      =Stand= with iris diaphragm                               =26.--=

[Illustration: Stand IV.]

  =Stand IV.=

The dimensions of this stand are now larger than formerly. The price has
not been changed.

  18. =Small Microscope.= Adjustable by sliding tube and
      micrometer-screw. The draw-tube is graduated in
      millimeters. Cylinder-diaphragm with sliding sleeve.
      Concave and plane mirrors, obliquely adjustable.
        Objectives 3, 6, 8.
        Eye-pieces I, III.
        Magnifications 60—550                                   =52.--=

  19. =The same.=
        Objectives 3, 7.
        Eye-pieces I, III.
        Magnifications 60-450                                   =36.--=

  20. =The same= without Cylinder Diaphragm, with Wheel
      Diaphragm.
        Objectives 3, 5, 7.
        Eye-pieces I, III.
        Magnifications 60—450                                   =44.--=

  21. =The same.=
        Objectives 1, 3, 7.
        Eye-pieces I, III.
        Magnifications 18—450                                   =40.--=

  22. =The same.=
        Objectives 3, 7.
        Eye-pieces I, III.
        Magnifications 60—450                                   =34.--=

      =Stand= with cylinder-diaphragm, without objectives
      and eye-pieces                                            =14.--=

      =Stand= with wheel-diaphragm, without objectives and
      eye-pieces                                                =12.--=

[Illustration: Stand V.]

  =Stand V.=

  23. =Small Microscope=. Adjustable by sliding tube and
      micrometer-screw. Concave mirror.
        Objectives 3, 7.
        Eye-pieces I, III.
        Magnifications 60—450                                   =30.--=

  24. =The same.=
        Objectives 3, 5.
        Eye-pieces I, III.
        Magnifications 60—250                                   =28.--=

  25. =The same.= Plane mirror.
        Objectives 1, 3.
        Eye-pieces I, III.
        Magnifications 18—80                                    =24.--=

  26. =The same.=
        Objectives 3.
        Eye-pieces I, IV.
        Magnifications 60—105                                   =18.--=

  27. =Stand= without objectives and eye-pieces                  =8.--=

[Illustration: Stand VI.]

  28. =Auxiliary Laboratory Stand=, for the examination of
      trichinae and for searching plate cultures. Very large
      stage (3-1/2×4 inch.). Adjustable by means of a carefully
      constructed rack and pinion, rendering it possible to
      focus objectives of fairly high power.
      =Stand=, without eye-pieces, objectives or case            =8.--=

      29. This stand fitted with objective 3, eye-pieces 0 and
      IV. Magnifications 40 to 100, in mahogany case fitted
      with lock                                                 =18.--=

 29a. =The same stand= fitted with eye-piece II and
      objective having separable front lens, yielding a
      magnification of 40 and 100 diam                          =18.--=

      =Glass compressor= with graduation                        =--.80=

      =Glass compressor= without graduation, per pair           =--.40=


  =Demonstration microscope.=

[Illustration: Demonstration microscope with condenser.]

 30a. Adapted for low and medium power. Square stage
      with wheel-diaphragm.

      Adjustment by sliding tube; after being adjusted
      the tube may be fixed by a ring clamp. Detachable
      handle.

      With clip to hold a sketch or label, etc. Stand
      without objective and eye-piece.                           =6.--=

 30b. =The same= with objective 3 and eye-piece I,
      magnifying 60 times                                       =14.--=

 30c. =The same= with adjusting screw for focussing high
      power objectives, with condenser and iris-diaphragm,
      without objectives and eye-pieces                         =18.--=

 30d. =The same= with objectives 3 and 6 and eye-piece I.
      Magnifications 60 and 255                                 =38.--=

[Illustration: Nebelthau's Sliding Microscope.]

  =Nebelthau's Sliding Microscope.=

  (Cf. Zeitschrift für wissenschaftliche Mikroskopie, XIII, 1896.)

 31. The sliding microscope is an instrument by means of
     which very large microscope sections, as, for example,
     large sections of the brain, can be systematically
     examined. It is also of service in looking over plate
     cultures of bacteria.

     The microscope is carried on a heavy beam supported
     by two stout pillars under which the stage
     moves. The various movements are accomplished by
     motion of the microscope on a lateral track upon
     its support and by motion of the stage on a similar
     track at right angles to the first. The motion of the
     microscope is by means of a screw, that of the stage
     by double rack and pinion. The extent of the movements
     is indicated in each case by a scale, thus
     permitting the systematic examination of the entire
     specimen.

     The stage consists of a glass plate, measuring
     16×20 cm, which is carried in a frame supported on
     four columns. The tracks permit a motion of the
     microscope of 18 cm and of the stage of 13,5 cm. A
     mirror under the stage affords ample illumination.

     The microscope tube is so arranged that it can be
     easily removed from the stand and a simple lens substituted
     for it. The coarse adjustment of the microscope
     is by rack and pinion. A screw above the objective
     serves for fine adjustment. The price of this sliding
     microscope, without objectives or oculars, but with a
     lens holder and simple lens magnifying eight diameters
     is                                                         =80.--=

     =Flat glass dish= of the same size as the stage to hold
     very large sections for the purpose of examining them
     while in clearing fluid                                     =1.25=

[Illustration: Dölken's Microscope stand.]

  32. =Dölken's Stand.= (p. 52) The stand is larger than
      Stand No. Ia, but is modified as shown in the cut so as
      to permit the examination of unusually large
      preparations. It is provided with the illuminating
      apparatus b (p. 22) and with all the adjustments
      necessary to the use of high powers.

      =Stand= and illuminating apparatus, without nose-piece    =80.--=

[Illustration: Travelling Microscope No. 33.]                                                                 $

  33. =Travelling Microscope.= This microscope is ready for
      use after spreading the foot, drawing out the tube and
      setting the mirror and stage in position. It is provided
      with all the adjustments of Stand No. V, consisting of
      fine adjustment by micrometer-screw, coarse adjustment
      by rack and pinion and illuminating apparatus d (p. 22).
      The box is arranged so as to accommodate three
      objectives and two oculars. It locks, has a handle, and
      measures 25×15×7 cm, the whole apparatus weighing 5
      pounds.

      Price of this microscope with illuminating apparatus,
      but without objectives or oculars                         =32.--=

      =The same=, without illuminating apparatus                =24.--=

[Illustration: Large Travelling Microscope No. 34.
(Size of mahogany case 28×19×8 cm.)]

This instrument (in size like the Ib.) combines all the essential
features of a large laboratory microscope with a folding stand. It will
be found invaluable on scientific expeditions, for research work etc.

When lifted out of the case, spread the two parts forming the base,
which are then held by a spring-catch. After raising the tube, turn the
stage around and tighten it by means of a lever. It is supplied with
large Abbe condenser and Iris diaphragm adjustable by side screw. Coarse
adjustment by rack and pinion, fine adjustment by micrometer-screw.
Graduated draw-tube. The stand has joint for inclination.

[Illustration: Large travelling microscope No. 34 (set up).]

  34. =Stand= with Abbe Condenser and Iris-Diaphragm, double
      nose-piece                                                =66.--=

  35. =The same=, with objectives 3, 6, Oil-Immersion 1/12",
      N. A. 1,30. Eye-pieces I, III. Magnifications 60—800     =128.--=

[Illustration: Horizontal-Microscope.]

  36. =Horizontal Microscope.= This instrument consists of
      a microscope tube placed horizontally on a long
      extensible column, supported in turn by a tripod base
      provided with levelling screws and a round spirit level.
      The extension of the upright supporting column is
      accomplished by two sliding motions, the lower,
      controlled by a set screw only, being intended for
      coarser adjustments, the upper, controlled by rack and
      pinion, for finer adjustments. A millimeter scale and a
      vernier serve to indicate the degrees of the various
      motions, so that vertical motion of the microscope tube
      to the extent of 1/10 mm may be accomplished.

      The microscope tube carries a spirit level and revolves
      upon a horizontal disc. The objective, consisting of two
      separable doublets, permits three degrees of
      magnification of 5, 9 and 48 cm focal distance
      respectively. A rack and pinion adjustment serves as
      adjustment of the microscope tube. A micrometer, 1 cm
      long and divided into 100, in the diaphragm of the
      ocular still further increases the availability of the
      instrument for making fine and accurate measurements.

      The instrument serves as a useful aid in many physical
      and physiological investigations.

      Price, including objective, ocular and micrometer         =40.--=



  =Microscopes for Mineralogical Research.=


We construct two Microscopes for mineralogical investigations. Both are
adapted for determining the axes of elasticity and for the
differentiation of isotropic and anisotropic bodies. Stand I alone is
adapted for determining the optical axes and their angles.

Only such objectives, condensers and oculars are available for
mineralogical examinations as have been shown after careful examination
in polarized light to be free from polarization.

[Illustration: Mineralogical Stand I.]


  =Mineralogical Stand I.=

  37. This microscope corresponds in its dimensions to
      Stand Ia as described on page 31. Coarse adjustment by
      rack and pinion, fine adjustment by micrometer-screw,
      the milled head of which has 50 divisions, each
      representing a motion of the objective of 1/100 mm. The
      condenser, iris-diaphragm and polarizer can be raised
      and lowered by rack and pinion. A triple condenser
      facilitates the observation of the axial lines in the
      microscope. It is so arranged as to be easily replaced
      by a simple diaphragm-carrier. By means of a collar
      attached to the end of the tube the objective is brought
      into coincidence with the centre of the revolving stage.
      This revolving stage is divided into 360 degrees and
      fitted with a vernier and index. Two scales on the
      stage, at right angles to each other, permit accurate
      location of specimens. The Nicol prism, which serves as
      a polarizer, can, after turning the iris-diaphragm
      aside, be drawn out from under the latter. The zero
      position of the Nicol prism is indicated by a line, as
      well as the angles 90, 180, 270°. The analyser is
      mounted in metal and is firmly fixed above the eye-
      piece. The analyser rotates on a disc graduated to 360
      deg. The front of the tube has a movable window which
      provides access to the inner tube. In the latter is an
      opening for the introduction of a Bertrand lens. This
      lens serves the purpose of magnifying the interference
      figures produced by the converging rays of polarized
      light. This lens and the eye-piece can be raised or
      lowered by rack and pinion. In the analyzer is a slide
      for the insertion of gypsum and quartz plates at an
      angle of 45 degrees.

      In many investigations it is advisable to employ an
      analyzer introduced laterally into the tube, instead of
      the one mentioned above.

      The following parts are supplied to complete the outfit:
        Triple nose-piece.

        Eye-piece 0, with Bertrand's quartered quartz plate.

        Eye-piece I with cross-lines, Brezina's Calcspath-plate,
        cleft perpendicularly to its axis, made to fit over
        eye-piece I, Klein's gypsum and quartz plates for
        insertion in the opening over the objective.

        Price of the stand with these accessories              =160.--=


  38. =The same= with eye-piece III, objectives 1, 3, 5, 7.
      1/12 Oil-Immersion, magnifications 18—800                =236.--=

      The new mechanical stage No. 98 (See page 78) can be
      fitted to the stand for the purpose of investigating
      large preparations and serial sections.

        Price                                                   =28.--=

[Illustration: Mineralogical Stand II.]

  =Mineralogical Stand II.=

  39. The base and pillar are in one piece, neatly
      japanned black. The coarse adjustment is by rack and
      pinion.

      The stage is revolving and graduated on the edge into
      360 degrees. A pointer indicates its position.

      The polarizer has stop at zeropoint and also marks at 90°,
      180° and 270°. It is held in a spring-sleeve and the
      substage can be raised and lowered by lateral screw, or
      may be swung to one side. The condenser is mounted in
      separate arm above the polarizer and swings out of the
      optical axis by means of a lever, if parallel instead of
      convergent rays are desired.

      The analyzer fits into an opening of the tube above the
      objectives and can be instantly thrown in or out of the
      optical axis. There is a slot below the analyzer for the
      insertion of quartz and gypsum plates.

      By means of a collar with two centering screws attached to
      the end of the tube, the objective may be brought into the
      optical axis.

      Price of this microscope with eye-piece I with cross-lines,
      Klein's quartz wedge and gypsum plate, red, I. order
      =$56.--=

  40. =The same= with eye-piece III. and objectives 3 and 5.

       Magnifications 60-250                                    =74.--=



  =Dissecting Microscopes and Hand Lenses.=

[Illustration: Large Dissecting Microscope No. 41.]


  41. =Large Dissecting Microscope.=

      Stand on heavy horse-shoe base, large stage with glass
      plate, adjustment by rack and pinion. The lens-carrier
      is movable for examining large plates. Illumination by
      movable plane mirror and white glass plate. Metal hand-
      rests covered with leather may be attached to the sides
      of the stage. They fit inside the mahogany case.

      A black metal plate with wheel-diaphragm or a milk-
      glass-plate can be inserted below the stage, serving as
      dark or white back-ground respectively.

      Stand without lenses in mahogany case                     =16.--=

  42. =The same= with three aplanatic lenses after
      Steinheil, magnifying 8, 16 and 20 diameters              =28.--=

  43. =The same= with these lenses and Abbe's drawing
      apparatus                                                 =40.--=

  44. =The same stand= with prism-tube No. 49 for erected
      image. Objectives 1*, 2, 3, magnifying 18, 40 and 80
      diam.                                                     =47.25=

[Illustration: Simple Dissecting Microscope No. 45.]

  45. =Simple Dissecting Microscope=, with adjustment by
      rack and pinion, movable plane mirror and white glass
      plate, glass stage in metal frame. Metal hand-rests
      covered with leather fit inside the case. Stand without
      lenses                                                     =8.--=

  46. =The same= with two aplanatic lenses after
      Steinheil, Magnification 10 and 20 diam.                  =16.--=

  47. =The same stand= with prism-tube No. 49, for erected
      image; with objectives 2 and 3, magnifying 40 and 80
      diam.                                                     =36.--=

[Illustration: Dissecting microscope with erected image after R.
Pfeiffer.]

=The Dissecting microscope with erected image according to Prof. R.
Pfeiffer= has been constructed in such a way that all parts extending on
both sides can be folded or turned, so that the instrument fits in a
very small case.

The base consists of two parts which may be folded. The stage can be
brought in a position vertical to the optical axis and the metal hand
rests laid on top of the stage. They are connected with the latter by
joints. The mirror can also be turned and put parallel to the pillar.

A round glassplate is set in the stage, below which is an iris diaphragm
to properly regulate the illumination.

The adjustment is by rack and pinion.

Two rightangle prisms are mounted inside the tube in such a manner that
the image obtained by the objective is reflected into the eye-piece and
appears erected.

The eye-piece is of the Ramsden form. Three objectives of different
magnifying power with specially long working-distances have been
constructed Nos. 1, 2, 3.

      The following table shows the magnification of the
      objectives in connection with the eye-piece.

               Objective     1        2       3
           Magnification    18       40      80 diam.
        Working distance    58 mm    18 mm    6 mm

          Prices:

  48. Folding dissecting microscope, stand only                 =24.--=

  49. Upper part of the microscope, consisting of tube
      with prisms, and one eye-piece                            =16.--=

  50. Objectives 1, 2, 3, a $ 6,00                              =18.--=
                                                              ---------
  51. Stand with complete outfit                                =58.--=

      The instrument is furnished in a mahogany case with
      nickelplated handle, lock and key.

[Illustration: No. 52.  No. 53.  No. 54.
Lens-holders.]

  52. =Lens-holder= on iron foot with moveable arms, the
      joints of which may be fixed by thumb-screws, rack and
      pinion adjustment--without lens                            =7.20=

  53. =Lens-holder=, nickel-plated stand with attachment
      of the collar holding the lens by ball and socket joint    =4.--=

  54. =Lens-holder= on heavy iron foot, ball and socket
      joints, adjustable to any position--without lens           =3.25=

  55. =Pocket microscope.= The size of an eye-piece, in box      =3.25=

  56. =Lens= for examining Algae                                 =1.25=

[Illustration: Dissecting Stage No. 57. With Lens No. 71.]

  57. =Dissecting Stage= with white glass plate and moveable
      lens-holder--without lens                                  =2.--=

  58. The same with lens No. 71                                  =3.25=

[Illustration: Simple Dissecting Microscope No. 58a.]

 58a. =Simple Dissecting Microscope=, consisting of a
      wood case with plate glass stage, movable plane mirror,
      two simple lenses of 4 and 8 times magnification. Price    =2.--=

 58b. =The same= with metal hand rests, moveable lens-holder
      and doublet magnifier No. 71, Price                        =3.50=

[Illustration: Demonstration lens-holder No. 59.    Focussing-lens
                         Handle No. 61.                 No. 60.]

  59. =Demonstration lens-holder=, consisting of a
      hardrubber stage with handle, clamps for holding the
      preparation in position, and with a moveable lens-
      holder. Without lens                                       =2.40=

  60. =Focussing lens= for photographic camera. Lens in
      spring-sleeve with clamping ring                           =4.75=

  61. =Handle= with ring for holding lens                        =1.25=

[Illustration: Steinheil lens No. 63.    Steinheil lens No. 66.]

      The =aplanatic triplets after Steinheil= are remarkable
      for their large, flat field and excellent definition,
      free from chromatic aberration.

            Diameter  Visual field  Magnification

  62.         24 mm       20 mm        8 diam.                   =4.--=

  63.         15 "        15 "        10   "                     =4.--=

  64.         12 "        12 "        12   "                     =4.--=

  65.         10 "        10 "        16   "                     =4.--=

  66.          6 "       3,5 "        20   "                     =4.--=

  67.          5 "         2 "        30   "                     =4.--=

  68.          3 "         1 "        40   "                     =4.--=

      The =achromatic doublets= have a very large, clear and
      flat field.

  69.         30 mm       35 mm        5 diam.                   =4.--=

  70.         23 "        20 "         8   "                     =3.25=

      =Doublet magnifier=, consisting of two double convex
      lenses.

  71.  23 mm  25 mm  6 diam.                                     =1.25=

      The doublet No. 69 can only be used as a hand lens. The
      mounting of all the other lenses is such that they fit
      any of the dissecting stands or lens holders. Aplanatic
      triplets 64-68 can only be used on stands with rack and
      pinion adjustment.

[Illustration: Doublet No. 70.]

[Illustration: Doublet No. 71.]

[Illustration: Pocket lens No. 72.]

      72. The aplanatic lenses Nos. 62-66 are also to be had
      with a moveable cover and ring adapting them for use as
      pocket lenses.

  Price, when thus mounted                                       =4.75=

[Illustration: Binocular Preparation Microscope.]

  73. =The Binocular Preparation Microscope=, after the
      model of Eilhard Schulze permits the convenient use of
      both eyes in dissecting small anatomical and botanical
      preparations. It consists of two Brücke lenses, adjusted
      to an accurate focus.

      Both tubes are moveable on a joint and are adjustable to
      various distances between the observers eyes. The
      distance of the eye from the preparation is about 250
      millimetres; the field of vision is large and flat; the
      magnification, four diameters; lenses are adjustable to
      either vertical or horizontal position and may be raised
      and lowered on the vertical support, thumb-screws fixing
      them in the desired position. A rack and pinion serves
      as fine adjustment                                        =24.--=

[Illustration: Greenough's Binocular Microscope.]

  74. =Greenough's Stereoscopic Binocular Microscope.=
      Two microscope tubes are so arranged as to bring the
      same object into focus in the axis of each tube, the
      tubes being set at an angle to each other for this
      purpose. The stand is provided with rack and pinion
      adjustment and both draw-tubes are also regulated by a
      rack and pinion arrangement, so that they may be adapted
      to the correct distance of the observers eyes.

      By interposition of prisms the image is rendered erect.
      Magnification, 20 diam.                           Price   =80.--=

 74a. =Corneal-Microscope=, is designed for the examination of
      the interior of the eye.

      =Prismtube= No. 49 with eye-piece                         =16.--=

      =Objective= of low power permitting 2 degrees of
      magnification                                              =6.--=

      =Stand= on heavy base, with rack and pinion adjustment
      etc.                                                       =8.--=
                                                                -------
                                                                =30.--=



  =Apparatus for Blood Examinations.=

[Illustration: Micro-Spectroscope.]

  75. =The Micro-Spectroscope= fits into the tube of the
      microscope like any ordinary eye-piece and may be fixed
      in any desired position by means of the thumb-screw M.
      The position of the bright and dark lines of the
      spectrum and their respective wave lengths are
      ascertained by means of a scale. The flat drum A, the
      interior of which is shown in section, contains the slit
      and the comparison prism. The slit is regulated by the
      screws F and H. The lever T moves the comparison prism
      across one half of the slit. The cylinder Q above the
      eye-piece contains the Amici prism. At the point N of
      the horizontal tube RN is the micrometer scale,
      illuminated by the mirror O. After raising the spring-
      catch L the upper part of the spectroscope may be turned
      round the pivot K, thus allowing of the adjustment of
      the eye-piece                                             =66.--=

        (A full description accompanies each instrument.)

  76. =Hand-Spectroscope=, Browning's, for spectroscopic examination
      of the blood                                              =12.--=

 76a. =Hand-Spectroscope= with comparison prism, mirror,
      and holder for vials                                      =16.--=

[Illustration: Thoma's Haemacytometer.]

  77. =Thoma's Haemacytometer= consists of an object glass
      with carefully constructed cell, a ground absolutely
      plane coverglass and two pipettes for mixing the blood
      and saline solution used in the examinations. One of
      these pipettes, for estimating the number of red
      corpuscles is so graduated as to permit dilution of the
      blood 100 or 200 times as required; the other, for
      counting the white corpuscles (leucocytes), is graduated
      for dilution of the blood 10 or 20 times.

      The volume contents of the pipettes are most carefully
      determined and the depth of the cell is established by
      accurate micrometric measurement, thus permitting very
      exact observations by means of this instrument.

        (A full description with each instrument)               =14.50=

  78. =Mixing-Pipette for white corpuscles=                      =3.60=

  79. =Mixing-Pipette for red corpuscles=                        =3.60=

  80. =Thoma counting chamber, with coverglass=                  =5.75=

  81. =Türck counting chamber with coverglass=                   =7.25=

[Illustration: Counting chamber
after Thoma       after Türck.]

[Illustration: Ehrlich's Eye-piece.]

  82. =Ehrlich's Eye-piece= is provided with a diaphragm
      having a square opening, the size of which is regulated
      by a small lever.

      This eye-piece is designed to facilitate the estimation
      of the relative numbers of red and white blood
      corpuscles in dry preparations.

      Full directions accompany each instrument                 =12.--=

 82a. =Apparatus= for the clinical determination of the
      alcalinity of the blood, after Prof. C. S. Engel.

      The following parts compose the apparatus:

      1) a capillary pipette so graduated as to permit the
      dilution of 0,05 cc. blood from the finger, up to 5 cc.
      with distilled water.

      2) a beaker, for the reception of the diluted blood.

      3) a burette mounted on stand, capacity 10 cc. Full
      directions accompany each outfit. Price in box             =8.--=



  =Micrometers.=

[Illustration: Screw Micrometer Eye-piece.]

  83. =Screw-micrometer eye-piece= for accurate
      measurement of large objects. Between the eye lens and
      the collecting lens of a Huyghenian ocular there is a
      millimeter scale etched on glass, above which is a
      moveable indicator whose position is controlled by a
      micrometer screw to which a graduated drum is attached.
      The value of each graduation on the drum (about 1/20 of
      the micrometer value of the objective) must be
      determined for each combination of ocular and objective
      by means of the stage micrometer. The eye lens of the
      ocular is moveable to permit accurate focus upon the
      scale. The apparatus slips into the tube of the
      microscope like any ordinary eye-piece and is fixed in
      position by a thumb-screw at the side                     =20.--=

  84. =Micrometer eye-piece.= The mount unscrews in the
      centre to permit the introduction of the micrometer
      scale. The eye lens is moveable to permit of accurate
      focus on the scale                                         =4.--=

  85. =Glass-Micrometer for the eye-piece=, to drop on the
      diaphragm of the eye-piece. Scale of 5 mm divided into
      100 parts                                                  =2.50=

  86. =The same=, 10 mm divided into 100 parts                   =2.--=

  87. =Stage-Micrometer=, 1 mm divided into 100 parts
      etched on glass                                            =3.75=

  88. =Stage-Micrometer=, photographed on glass, 2 mm
      divided into 200 parts                                     =1.40=

  89. =Eye-piece Micrometer=, divided into squares for
      counting scattered objects in the field. Mounted.
      Distance between the lines 0,5 mm                          =2.--=

  90. =Glass slide with cell= 2/10 mm deep, with ocular
      micrometer No. 89, in box                                  =3.25=

  91. =Glass slide with cell= the floor of which is
      divided into squares, 1/400 square mm each, in box         =4.--=



  =Drawing Apparatus.=


      The two following =drawing eye-pieces= Nos. 92 and 93,
      have quickly found favor among those having frequent
      occasion to make drawings from microscopic preparations
      and are now largely used in educational institutions as
      an aid to students in the study of their specimens. In
      both eye-pieces the prism is so adjusted as to
      accomplish total reflection of the image, thus doing
      away with loss of light and with secondary reflections,
      such disturbing features of those forms of drawing
      apparatus of which a mirror forms an essential part.

[Illustration]

  92. This =drawing eye-piece= is employed with the stand
      in the vertical position. The reflected image lies at
      the side of the microscope, the rays passing off at an
      acute angle from the reflecting prism near the top of
      the eye-piece. The eye-piece slips into the tube of the
      microscope like any ordinary eye-piece and is held in
      position by a thumb-screw. The drawing field is at once
      visible without further adjustment, and the picture is
      clear and sharp. The brightness of the drawing field may
      be regulated by smoked glass plates mounted in two
      moveable metal arms                                        =8.--=

[Illustration: Drawing eye-piece for drawing with inclined stand.]

  93. This =drawing eye-piece= is similar in construction
      to that just described, but is so arranged as to throw
      the image vertically downwards behind the microscope
      when the latter is inclined at an angle of 45 degrees.
      In this case also the picture reflected is clear and
      sharp, devoid of all disturbing secondary images. As the
      image is reflected vertically downwards upon the table,
      no special drawing stand is necessary as there is no
      distortion of the picture. The intensity of the light
      may be modified by smoked glass plates mounted in two
      moveable metal arms                                       =10.--=

      For a description of these drawing eye-pieces and of the
      principles involved in their construction reference may
      be had to the Zeitschrift für wissenschaftliche
      Mikroskopie, XII, 1895.

[Illustration: Abbe's Drawing Apparatus.]

  94. In =Abbe's Drawing Apparatus= the drawing field is
      reflected by a mirror at the side of the instrument and
      by a prism which fits over the eye-piece of the
      microscope. The prism is supported on a vertical hinge
      so that it may be readily turned out of the axis of the
      microscope without disconnecting the whole apparatus
      from the stand. It is shown turned to the side in the
      figure. A cylindrical cap accompanies the apparatus
      which fits over the prism holder and has six lateral
      windows in which are smoked glasses of various
      intensity, serving to regulate the lightness of the
      reflected drawing field                                   =12.--=

[Illustration: Drawing Board No. 95. Drawing Board after Giesenhagen.]

      The =Drawing boards= serve two purposes. They afford a
      smooth plane surface for the drawing paper and they are
      so arranged that they may be inclined at such an angle
      as to receive the rays of the reflected image at right
      angle to their surface, thus doing away with any
      distortion of the image on the paper.

  95. This =drawing board= is especially adapted for use
      with drawing eye-piece No. 92. When in the position
      indicated in the figure its drawing surface forms an
      angle of 12° to the horizontal                             =2.--=

  96. In =Giesenhagen's drawing board= the drawing surface
      may be adjusted at various angles and may be raised and
      lowered                                                    =4.--=

      For drawing eye-piece No. 93 and the Abbe drawing
      apparatus the surface of the drawing board should be
      horizontal.

[Illustration: Drawing apparatus after v. Tubeuf.]

  97. The =drawing apparatus= after v. Tubeuf serves for
      drawing objects from nature. By means of a prism mounted
      in a metal box, the object is reflected into the eye in
      such a manner that its image appears erected on the
      drawing surface. This is quite an advantage when drawing
      from nature but is unimportant when using a drawing
      apparatus on the microscope. Two smoked glasses mounted
      in moveable metal arms serve to moderate the intensity
      of the light. On the side of the prism nearest the eye
      is a small wheel diaphragm attached to regulate the size
      of the opening. The apparatus is mounted on a heavy
      nickel-plated stand with vertical and lateral
      adjustments controlled by thumb-screws                    =12.--=



  =Mechanical Stages.=

[Illustration: Mechanical stage No. 98.]

  98. =Mechanical stage= adapted to Stands I, Ia and Ib.
      The stage is readily attached to the microscope by means
      of a small screw, _C_, which screws into a thread in the
      microscope just behind its stage, and binds the
      mechanical stage firmly in position and always in the
      same position. It may be again removed by simply
      unscrewing this set screw.

      The movements of the stage are at right angles to one
      another, are accomplished by carefully constructed rack
      and pinion adjustments and the exact position of each
      adjustment is indicated by vernier scales. The extent of
      the lateral movement is 50 mm; that of the other 30 mm.

      This stage permits the careful and systematic
      examination of large specimens and its construction is
      so perfect that by means of the vernier scales the most
      minute objects may be readily replaced in the field of
      vision, even after removal and readjustment of the
      stage, provided only that their location when in the
      field of vision as indicated by the scales had been
      noted                                                     =28.--=

  99. =Large mechanical stage= for stand, _A_, adapted for
      slides 50×100 mm; both movements by rack and pinion
      adjustments                                               =32.--=

[Illustration: Mechanical stage No. 100.]

 100. =Mechanical Stage No. 100.= When a mechanical stage
      is ordered subsequently to a microscope outfit and under
      such circumstances that its correct adjustment to the
      stand by a skillful mechanic is impossible we advise the
      purchase of this more readily adjusted mechanical stage,
      which may readily be attached to Stands I, Ia, Ib, IIa
      and IIb by means of a thumb-screw. It is as carefully
      constructed as Mechanical Stage No. 98 and serves the
      same purpose in every particular                          =28.--=

100a. =New Mechanical stage=, simplified form                   =20.--=

[Illustration: Mechanical stage No. 100a.]

 101. =Warm stage= after Schultze. This consists of a
      metal stage to which long lateral arms are attached,
      through which the heat from one or more small lamps is
      conducted to the central part of the stage and the
      object. The apparatus is also provided with a condenser,
      which affords illumination sufficient for the use of
      high power objectives, and with a thermometer indicating
      the exact temperature of the centre of the stage, which
      may be carried as high as 100° C.                         =12.--=

[Illustration: Schultze's Warm Stage No. 101.]

 102. =Warm stage= after Pfeiffer. It consists of a glass
      chamber through which warm water may be made to flow. A
      small cell is ground in its surface thus permitting its
      use as a moist chamber                                     =6.--=

 103. =Warm stage= after Stricker. This stage consists of
      a metal chamber, through which warm water is made to
      flow when in use, and is provided also with a condenser
      and thermometer. It may be screwed firmly to any of the
      square microscope stages                                  =14.--=

[Illustration: Stricker's Warm stage No. 103.]

 104. =Warm stage= after Errera, permitting rapid changes
      from low to high temperature and vice-versa.

      It includes 2 vessels for cold and hot water, mounted on
      tripods, with rubber-tubing etc.                          =24.--=


  =Photo-micrographic Apparatus.=

[Illustration: Photo-micrographic Apparatus No. 105.]

The method of employing this apparatus and the general technique of
photo-micrography are treated of in a separate pamphlet containing also
four photo-micrographs taken with this apparatus.

This little work is furnished with each apparatus.

 105. =The Photo-micrographic Apparatus= consists of a
      heavy iron foot supporting a stout column in which
      another iron support moves vertically. This latter holds
      the camera and may be firmly fixed at any height by
      means of a thumb-screw. This permits the accurate
      adjustment of the camera to microscope stands of various
      sizes. The length of the camera is also adjustable by
      means of a thumb-screw sliding in the upright support.
      Regulation of the field of the camera is accomplished by
      a revolving disc diaphragm with openings of five
      different sizes situated in the neck of the camera. Two
      simple plate-holders for plates 9×12 and 13×18 cm are
      supplied with each camera, as are also a ground glass
      plate and clear glass plate in the frame of the camera
      serve to catch the picture in the plane of the
      photographic plate, and a simple lens aids in obtaining
      a correct focus of the image. A white glass plate,
      mounted on a stand is of use in diffusing direct
      sunlight so as to make it available for photographic
      purposes, and three discs of yellow, blue and green
      glass are provided which may be inserted over the iris-
      diaphragm of the condenser when colored light is
      required.

      It is of great advantage to interpose an illuminating
      lens between the source of light and the mirror, thereby
      condensing the light-rays, giving a uniform illumination
      and preventing the heating up of the entire stand, which
      is a disturbing factor in retaining the focus. The
      illuminating lens also serves to lessen the time of
      exposure.

      This photo-micrographic apparatus is also available when
      it is desired to photograph gross specimens as, for
      example, embryos, insects, etc., by reflected light, as
      is represented in the figure on p. 86. The photographic
      objective of 64 mm focal distance, is best adapted to
      this purpose. It fits in a collar in the neck of the
      camera and yields a magnified image of about 3
      diameters. The object is brought into proper focus by
      means of a small stand, the table of which may be raised
      or lowered as required.

      Price of the apparatus without microscope stand           =40.--=

 106. =Small stand for supporting specimens= to be
      photographed by reflected light as mentioned above         =4.75=

 107. =Welsbach lamp= with reflector                             =6.--=

 108. =Illuminating lens= of 100 mm diam. on stand              =12.--=

 109. =Photo-micrographic apparatus=, for use in
      horizontal and vertical position. It is in construction
      similar to the foregoing, but is provided with joint for
      inclination and clamping lever, and can be used at any
      angle.

      Large size bellows and plateholder, for plates up to
      24×24 cm. Moveable platform with three leveling screws
      and clamping-bar for holding stand. Price of the
      apparatus, with 2 simple plate-holders, ground and plain
      glass plate, etc., without microscope stand               =60.--=

[Illustration: Photo-micrographic Apparatus No. 109.]

  =Edinger's Projection Apparatus.=

[Illustration: Edinger's Projection Apparatus with Nieser's Photographic
Camera.]

 110. =Edinger's Projection Apparatus=--For projecting
      and drawing large objects slightly magnified. (Cf.
      Zeitschrift für wissensch. Mikroskopie. VIII. 1891.)

      A polished wooden base, in which a lime wood drawing
      tablet is inlaid, supports a wooden stand which in turn
      holds a horizontal metal tube in which are a collecting
      lens and a reflecting mirror. The upright also carries,
      two arms, by rack and pinion adjustment, the one
      supporting the object stage, the other regulating the
      length of the camera. On the other side of the upright
      is a support for a lamp. The rays of this lamp are
      converged by the collecting lens upon the mirror, are
      reflected downward to the object and through the
      objective to the drawing board below. The various
      adjustments permit considerable variation of
      magnification with the same objective.

      Price, including lamp                                     =18.--=

      For photographic purposes this same apparatus may be had
      with Nieser's photographic camera, plate holders,
      focussing plate etc.

 111. =Edinger's Projection Apparatus with Camera= for
      plates 9×12 cm and 13×18 cm                               =38.--=

 112. =Larger Projection Apparatus with Camera= for
      plates 9×12, 13×18, 18×24 and 24×30 cm                    =56.--=

      The following Objectives of 24, 35, 42 and 64 mm focal
      distance respectively may be used in connection with
      this apparatus for photographic purposes.

 113. }                            { of 24 mm focal distance    =18.--=
 114. }  =Photographic Objectives  {  " 35  "   "       "       =18.--=
 115. }  with Iris diaphragms=     {  " 42  "   "       "       =18.--=
 116. }                            {  " 64  "   "       "       =20.--=

      The following table shows the size of the preparation
      which may be resolved by each one of these objectives
      and the magnification with the smaller and with the
      larger Edinger Projection Apparatus.

  -------------+----------------+--------------------------------------
               |  Size of the   |              Magnification
   Objective   |  Preparation   |                    |
  Focal length |    Maximum     |  Smaller Apparatus | Larger Apparatus
  -------------+----------------+--------------------+-----------------
    24 mm      |     8 mm       |     7-15 diam.     |    13-25 diam.
    35 mm      |    15 mm       |     5-12 diam.     |    10-20 diam.
    42 mm      |    20 mm       |      3-9 diam.     |     6-13 diam.
    64 mm      |    35 mm       |      2-4 diam.     |      3-8 diam.
  -------------+----------------+--------------------+-----------------

The time required for exposure in photographing with this
apparatus is from 5 to 20 seconds according to the magnification
and character of the specimen.

The following figure shows a further use for the Objective
of 64 mm focal distance in connection with the photomicrographic
apparatus (page 82).

[Illustration: Photo-micrographic apparatus No. 105 with small stand No. 106.]



  =Large Projection Apparatus.=

In this projection apparatus an electric projection lamp is made use of,
the lamp being available for electric currents of 20 Ampères and about
48 Volts. To regulate the current a rheostat is necessary. When using
constant current the carbons should stand at an angle in order to
utilize to best advantage the stronger light of the positive (upper)
carbon. For spectroscopic projections the carbons of the lamp have to be
in vertical position.

Connected with the lamp is a triple condenser of 150 mm aperture. The
latter should be protected from the heat-rays by a large mica-plate
which is furnished with the apparatus.

Various devices permit very accurate adjustment of the lamp and
condenser. For example, two thumb-screws control the position of the
carbons of the lamp so that the luminous point may be readily brought
into the exact optical axis of the condenser. Again, the two inner
lenses of the condenser are moveable and are controlled by two knobs
conveniently situated as shown in the illustration.

By this adjustment of the lenses of the condenser it is possible to do
away with disturbing chromatic aberration. The rays of light leave the
condenser in moderate convergence.

For direct projection from the preparation the apparatus consists of the
optical bench upon which are mounted the various accessories in proper
succession (Fig. p. 88):

1. A large cooling cell, which is to be filled with water or alum
solution.

2. The bellows with tube. This is connected with the cooling cell by
means of a metal ring which slips over the end of the cell and is held
in place by a screw. The metal ring is attached to one end of the
bellows, while the other end carries a large tube.

3. The microscope condensers and diaphragm holder. A larger tube fits
over the tube of the bellows and carries on a revolving arm the cylinder
diaphragm and the two condensers. For low power objectives Nos. 1-3, the
cylinder diaphragm and the condenser of longer focus have to be used.
The latter at the same time serves as the objective for lantern slide
projection.

The other condenser is especially needed when high powers are employed
(Objectives 4 to 6). A small rack and pinion arrangement serves for the
adjustment of condenser and diaphragm.

4. The object stage and small cooler. The stage has connected with it a
second cooling cell on which the preparation rests. This arrangement
permits prolonged use of the condenser and the greatest intensity of
light without burning the most delicate specimens. The adjustment of the
object is accomplished by means of an arrangement which permits any
particular point to be brought accurately into the field.

[Illustration]

5. The objective carrier is provided with a nose-piece for three
objectives, with a broad projection tube, having an Iris diaphragm for
the purpose of narrowing the aperture, and with a narrow tube which
screws into the broad one, in case it is desired to use oculars in
making the projection. The adjustments of the objectives are
accomplished by rack and pinion and by micrometer screw.

In order to change readily from microscopic to lantern-slide projection,
the parts 4 and 5 have been provided with hinges, by means of which they
can be thrown to one side after loosening a lever (see illustration
below).

6. Wooden cover with cloth curtain which fits over the diaphragm
carrier, the stage and the objectives, to shut off any light which may
escape at the sides.

For the projection of large preparations of from 8-35 mm diameter our
photographic objectives of 24, 35, 42 and 64 mm focal distance are best
adapted (p. 86). In connection with these low powers the large tube only
should be used.

[Illustration]

With this projection apparatus the powers of microscope objectives till
number 6 may be well employed.

The picture, even when the highest powers are made use of, and the
screen is at a distance of twelve feet from the apparatus, is of
sufficient clearness and brightness to be available for demonstration to
a large audience.

For the projection of lantern slides or of large section of tissue
following parts of the apparatus are required: Lamp, condenser, cooler
and bellows are the same as in the above described apparatus.

The stage and objective carrier are swung to one side.

The special-projection lens of 300 mm focal distance is to be used.

A slide carrier slips into the frame of the bellows, which is
sufficiently large to accommodate lantern slides 9×10 and 9×12 cm in
size. The slide carrier has a stop at both ends which facilitates its
adjustment in the axis of the instrument, and is arranged for the
simultaneous reception of two slides, so that while one is being
projected it may be charged with a second which may then without delay
be pushed into the optical axis as the first is removed. In this way
series of pictures may be thrown on the screen without interruption.

When so arranged the projection can be made upon a screen 30 feet from
the apparatus, over the heads of an audience.

  Prices:

 117. =Projection-lamp= for current of 20 Ampères, with
      centering arrangement                                     =92.--=

      =Fixed rheostat=                                          =30.--=

        (The same, adjustable  =$45.--=.)

      Lamp and rheostat are furnished at factory prices. In
      ordering it is well to state the strength of the
      available electric current, also whether it is constant
      or alternating.


      =Outfit for projection of lantern slides:=

      Metal-base with optical bench, triple collecting lens
      (adjustable) of 150 mm aperture; large cooling cell;
      slide carrier with bellows; triple revolving arm, with
      rack and pinion adjustment                               =108.--=

      Projection objective of 300 mm focal length               =20.--=

        (A second objective of same focal length may be slipped
        over the former, the two combined represent an objective
        of 150 mm focus. Additional price =$20.--=.)


      =Outfit for microscopical projections:=

      Cylinder-diaphragm and condenser; objectstage and small
      cooler with moveable slide-holder. Objective carrier
      with triple nose-piece: rack and pinion adjustment and
      micrometer-screw. Broad tube with Iris-diaphragm into
      which the smaller draw-tube fits. Two projection eye-
      pieces.

      Object-stage and objective carrier are provided with
      hinges. Wooden cover with cloth curtain                   =84.--=
                                                     Transport =250.--=
                                                               --------
                                              Complete outfit  =334.--=


 118. =Megascope=, apparatus for the projection of opaque
      objects; special offers will be made on application.

 119. =Attachment for spectroscopic examinations=, to be
      used on the optical bench and in connection with the
      lamp of the projection apparatus No. 117. Slit
      mechanism, large triple prism, object-stage               =80.--=

 120. =Large projection apparatus=, of special design
      with latest improvements, for lantern slides size 13×18
      cm, for micro-projection, and megascope attachment.
      Special offers for this apparatus will be made on
      application.

        (In ordering it is necessary to state the voltage of
        the available electric current, also whether it is
        direct or alternating.)

 121. =Trichinoscope.= Simple electric lamp (hand feed)
      of 20 Ampère, mounted on adjustable stand, encased in
      Russian iron box, double collecting lens (adjustable) of
      120 mm Aperture, with condensing lens.

      Mechanical stage for glass compressors, with movements
      at right angles to each other, cooling cell for the
      preparation with a continual flow of cold water.
      Objective carrier with micrometer screw, wide tube with
      Iris diaphragm                                           =120.--=

      Projection objective of 35 mm focus, aperture f:3,5,
      with Iris diaphragm                                       =18.--=
                                                               --------
                                                               =138.--=

[Illustration: Trichinoscope No. 121.]



  =Microtomes.=

[Illustration: Large Sliding-Microtome.]

Our larger microtomes are heavy and all their adjustments are of the
most accurate construction, the result being that they are very steady
when in use and permit the cutting of very thin and uniform sections.

They are to be had in three different sizes. The larger two are slightly
different in construction from the third. The two former microtomes are
provided with an automatic feed attachement. A heavy knife-carrier
slides smoothly and rapidly on a horizontal track and is so arranged
that it may be manipulated by the hand of the operator alone or by a
wheel and chain device, which tends to assure a perfectly uniform stroke
of the knife.

The objectclamp is raised vertically by a micrometer screw. This motion
is accomplished by turning a large disc having teeth cut into its
periphery and a turn of one tooth being equal to an elevation of 0.0025
mm.

The automatic feed is arranged as follows: With each return of the
knife-carrier to the end of its track pressure is made upon an
adjustable lever which regulates the motion of the micrometer wheel.
This device may be so adjusted as to move the micrometer disc any number
of teeth from one to ten with each sweep of the knife.

Three different forms of clamps may be had for these microtomes, and
freezing apparatus as well as paraffin tables can also be fitted.

The Fixed clamp, No. 128, represented in the figure of the large sliding
microtome, serves to clamp the specimen in position and does not allow
any further adjustment.

The Ball and Socket clamp permits the adjustments of the specimen after
it is held in the clamp by means of a ball and socket joint--see figure
of No. 129--a set-screw then holds it firmly in position.

The Naples clamp permits the accurate adjustment of the specimen at any
level, the clamp being supported on two horizontal axes at right angles
to each other, the one controlled by rack and pinion, the other by
endless screw.

The knife-carrier is arranged to hold the Thoma form knives, which are
fastened by means of a wing-screw. Other knives require a special
holder, such as No. 139.

 122. =The Large Sliding Microtome= has a track 42 cm
      long. Its price with automatic feed attachement, wheel
      and chain arrangement for the knife carrier, and fixed
      clamp, without knife                                      =62.--=

 123. =The same=, with knife holder for Jung microtome
      knives                                                    =66.--=

 124. =The same=, but without the wheel and chain
      arrangement for the knife carrier                         =50.--=

 125. =Medium size Sliding Microtome=--Track 32 cm long;
      automatic feed attachement; wheel and chain motion of
      knife carrier and fixed specimen clamp--without knife     =56.--=

 126. =The same=, with knife holder for Jung microtome
      knives                                                    =60.--=

 127. =The same=, but without wheel and chain motion            =44.--=

 128. =Fixed Specimen Clamp=                                     =4.--=

 129. =Ball and Socket Clamp=                                    =6.--=

 130. =Naples Clamp=                                            =12.--=

[Illustration: Ball and Socket Clamp No. 129.    Naples Clamp No. 130.]

 131. =The Support-Microtome= has a track 19 cm long. The
      knife-carrier slides on a double flanged support and is
      moved by means of a large knob. The motion is smooth and
      quick. The specimen is held in a clamp supported on two
      adjustable axes at right angles to each other, thus
      permitting its adjustment in any position. The specimen
      carrier is moved vertically by means of a micrometer
      screw to which a large disc is attached. This disc is
      graduated, each degree representing a motion of the
      specimen carrier of 0,005 mm. The price of this
      microtome with knifeholder No. 139, without box or knife
      is                                                        =34.--=

[Illustration: Support-Microtome No. 131.]

131a. =Small Sliding Microtome=, length of bed 21 cm,
      heavy knife-carrier, object clamp for specimen 25 mm
      diam., micrometer screw with disc graduated into 100
      degrees, each division representing a motion of 0,005
      mm. Price including knifeholder No. 139, without knife    =24.--=

[Illustration: Small Sliding Microtome No. 131a.]


  =Microtome knives.=
  (Made by W. Walb.)

      =A. Thoma's Model=, plano-concave, with handle adapted
      for clamping immediately to the knife carrier of the
      microtome, in box.

[Illustration]

 132. Length of cutting edge 36 cm                              =26.50=

 133.   "    "     "     "   24 cm                              =13.25=

 134.   "    "     "     "   16 cm                               =8.50=

 135.   "    "     "     "   12 cm                               =5.50=

      =B. Jung's Model=--plano-concave--requires knife-holder
      No. 139--in box.

[Illustration]

 136. Length of cutting edge  24 cm                             =11.25=

 137.   "     "   "       "   17 cm                              =6.--=

 138.   "     "   "       "   12 cm                              =4.75=

 139. =Knife-holder= designed for Jung's Microtome knife         =4.--=

 140. =Freezing apparatus= for Microtomes                        =8.--=

[Illustration: Freezing apparatus No. 140.]


  =Hand Microtomes.=

[Illustration: No. 141.]

 141. This =Hand Microtome=, shown in the figure above,
      screws to the edge of the table. The specimen is held in
      a clamp which may be removed from the instrument, and
      which is raised by a micrometer screw to which a large
      disc is attached, the edge of which is milled and
      graduated, each degree of the graduation representing an
      elevation of the specimen of 1/100 mm. The knife is
      manipulated by hand and in cutting slides over two
      narrow glass plates which serve as a track for it. The
      length of this track is 7 cm                              =12.--=

 142. =Cylinder Microtome.= The specimen is held by means
      of a clamp-screw in a hollow cylinder. This entire
      cylinder is raised within another cylinder which bears
      the cutting table by means of a screw with milled and
      graduated head. Each division of the graduation
      represents a motion of the inner cylinder of 1/100 mm.
      In cutting the edge of the knife is made to pass over
      the surface of the glass cutting table, the diameter of
      which is 7 cm                                              =6.--=

[Illustration: Cylinder Microtome.]

 143. =Microscopic section-cutter=--razor form--of best
      quality, plano-concave, for microtomes No. 141 and 142     =1.25=



  =Miscellaneous Accessories.=

[Illustration:Analizer.  Polarizer.
Polarizing Apparatus No. 144.]

 144. =Polarizing Apparatus= for Food Analysis.

      The analizer forms part of an ocular which fits into the
      tube of the microscope and is provided with a graduated
      disc and index. It is fixed in any desired position by
      means of a thumb-screw.

      The polarizer, when used in connection with stands
      fitted with a substage condenser and iris-diaphragm, is
      hung in the carrier of the iris diaphragm; when used on
      other stands it takes the place of the cylinder
      diaphragm, and if desired may be furnished with a
      condenser. Price                                          =22.--=

 145. =Simpler Polarizing Apparatus.= The analizer is
      without an ocular and has no graduated disc. The
      polarizer is as described above                           =14.--=

 146. =Gypsum= and =Mica plates= set of 8                        =6.--=

 147. =Coverglass Tester=, for measuring the thickness of
      coverglasses                                               =3.75=

147a. =Coverglass gauge=, dial form, for the rapid and
      accurate measuring of coverglasses, thin plates etc. A
      slight pressure on a lever opens a pair of steel clips.
      The exact thickness is at once indicated by a pointer
      moving over a divided circle on the lid of a metal box.
      The gauge measures 0,01 up to 5 mm                        =12.--=

 148. =Nose-piece= for two objectives--Double nose-piece         =6.--=

 149. =Nose-piece= for three objectives--Triple nose-piece       =8.--=

 150. =Nose-piece= for four objectives--Quadruple nose-piece    =10.--=

      Nose-pieces can be adjusted to our stands at any time
      without charge.

 151. =Iris-diaphragm=                                           =6.--=

[Illustration: Illuminating Lens No. 152.]

 152. =Illuminating Lens on stand=, 100 mm diameter             =12.--=

 153. =Illuminating Lens on stand=, 60 mm diameter               =8.--=

 154. =Glass slides=, hollow, per doz                           =--.75=

 155. =Glass slides=, English form 3×1", of plate-glass
      with polished edges, per gross                             =1.--=

 156. =Glass slides=, with well, for moist chambers             =--.40=

 157. =Cover-glasses=, squares, 15×15 mm, per 100               =--.60=

 158. =Cover-glasses=, squares, 20×20 mm, per 100               =--.85=

 159. =Cover-glasses=, circles, 15 mm diameter, per 100         =--.85=

 160. =Cover-glasses=, circles, 20 mm diameter, per 100          =1.--=

[Illustration: Turn-table No. 161.]

 161. =Turn-table=, for ringing, with adjustable slide clips     =4.--=

 162. =Thickened Cedar Oil= for oil-immersion lenses, 1 oz      =--.40=

 163. =Object Marker.= This is designed to indicate the
      exact portion of an object which has been seen in the
      field of the microscope. After finding the required
      field, the objective of the microscope is unscrewed and
      the marker is screwed into the tube in its place. By
      then moving the tube so that the marker comes in contact
      with the object that portion of the object which
      occupied the optical axis of the microscope is indicated   =1.25=

 164. =Object Marker= with diamond point, by means of
      which the object can be marked by drawing a circle         =4.--=

 165. =Demonstration Ocular= of Kuznitzky (Cf. Zeitschr. f.
      wissensch. Mikroskopie, XIII, 1896).--Indicates any
      particular portion of the image to which it is desired
      to draw particular attention.

      A small lever at the top of the ocular moves an
      indicator just above the diaphragm of the ocular to any
      part of the field                                          =3.25=

[Illustration]

 166. =Opaque Illuminator=, for illuminating polished
      pieces of metal whose structure is to be investigated by
      means of high power objectives--A collar, carrying a
      prism, screws into the tube of the microscope, and by
      means of the prism sufficient light is thrown through
      the objective upon the otherwise opaque object to permit
      of its examination up to 1000 diameters magnification      =6.--=

 167. =Erecting Prism=--This is fastened over the ocular
      and erects the image received from the compound
      microscope, thereby materially assisting any dissection
      or other operation on the stage of the microscope          =7.25=

[Illustration]

 168. =Microscope= for the accurate reading of
      thermometer scales, after Fridtjof Nansen.

      Stand with spring-clamp to attach thermometers of
      various sizes. With micrometer ocular and objective
      magnifying 12 times                                       =20.--=

[Illustration: Saccharimeter No. 169.]

 169. =Saccharimeter=, Mitscherlich's (improved form),
      for determining the amount of sugar contained in
      liquids, glucose etc. by measuring the angle of
      rotation. Tube with concave mirror on stand, graduated
      scale with vernier and lens for reading one-tenth of a
      degree of rotation.

      The rotation of the Nicol prism with the vernier is
      performed by means of an endless screw. The adjustment
      is accomplished as soon as the two squares of the
      divided quartz-plate show the same color. Two tubes of
      100 and 200 mm length, for the liquid to be examined,
      are supplied with the apparatus. Should the rotation of
      the substance examined be excessive, it is necessary to
      use sodium light for illumination                         =52.--=


  =Microscopical cases.=

 170. =Case=, containing a razor, spatula, two small
      knives, straight and curved scissors, forceps, two
      needles, two lancet-shaped needles                         =5.50=

 171. =Case=, containing a razor, spatula, a small knife,
      two needles, small scissors, and forceps                   =4.--=

 172. =Case=, containing a small knife, small scissors,
      forceps and two needles                                    =2.50=

 173. =Botanical Outfit= in case, containing a small
      knife, forceps, self-closing forceps with horn handle,
      two scissors, two needles and two lenses                   =5.50=

 174. =Outfit for Sputum Examinations=, after Kaatzer,
      consisting of a platinum needle, blower, cover-glass
      forceps, and a small rubber plate                          =4.75=

 175. =Leather Microscope case= to protect the mahogany
      case when travelling                                       =8.--=

 176. =Leather case= to protect the mahogany cases of
      larger size instruments                                   =12.--=

 177. =Bell jar= for covering microscope                         =2.--=



  Any of the following publications will be sent on application:


1. Catalogue of microscopes etc., which has been issued in three
editions, viz. in

    a) English,

    b) German and

    c) French.

2. Anleitung zum Gebrauch des Microscops.

3. Instructions pour l'emploi des microscopes.

4. Directions for using the Microscope.

5. On the method of counting red and white corpuscles with Thoma's
Apparatus.

6. Instructions pour l'emploi de l'hématimètre de Thoma.

7. Anleitung zur Mikrophotographie, mit vier Mikrophotogrammen.

8. Anleitung zum Gebrauch des Mikrospectroskops.

9. Anleitung zum Gebrauch des Oculars nach Ehrlich.

10. Description de l'oculaire d'Ehrlich.

11. Direction for using Ehrlich's eye-piece.

12. Anleitung zum Gebrauch des grossen Projectionsapparates.

13. Anleitung zum Gebrauch des Saccharimeters.

[Illustration]



  =Index.=


                                                            Page
  =A.=

  Achromatic Objectives                                       12
  Adjusting screw                                             49
  Adjustment, coarse, fine                                17, 18
  Apertures                                                   10
  Aplanatic Lenses                                            67
  Apochromatic Lenses                                         14
  Apparatus for Blood Examinations                            70


  =B.=

  Binocular Preparation Microscope                            68
  Binocular Microscope after Greenough                        69
  Bell jar                                                   103


  =C.=

  Camera                                                  81, 84
  Cases for Stands                                            19
  Cedar Oil                                                  101
  Clamps for Microtomes                                       94
    fixed clamp                                               94
    ball and socket clamp                                     94
    Naples clamp                                              94
  Compensation Eye-pieces                                     14
  Compressors                                                 49
  Condenser                                                   20
  Corneal microscope                                          69
  Counting chambers                                           71
  Coverglass gauge                                            99
  Cover-glasses                                              100
  Cover-glasses thickness                                      8
  Coverglass Tester                                           99
  Cylinder Iris Diaphragm                                 20, 23
  Cylinder Microtome                                          98


  =D.=

  Demonstration Lens-holder                                   67
  Demonstration Microscope                                    49
  Demonstration Ocular                                       101
  Dissecting Microscopes                                      62
  Dissecting Microscope with erected image                    64
  Dissecting Stage                                            66
  Dölken's Microscope Stand                                   52
  Drawing Apparatus after Abbe                                74
  Drawing Apparatus after Tubeuf                              77
  Drawing Board                                               76
  Drawing Eye-pieces                                          74


  =E.=

  Edinger's Projection Apparatus                              84
  Engel's Alcalinity Apparatus                                72
  English screw                                               18
  Erecting prism                                             102
  Eye-pieces:
    Compensation Eye-piece                                    14
    Demonstration Ocular                                     101
    Huyghenian Eye-piece                                      11
    Micrometer Eye-piece                                      73
  Ehrlich's Eye-piece                                         72
  Eye-piece with cross lines                                  59
  Eye-piece Micrometer with squares                           73


  =F.=

  Freezing Apparatus                                          97
  Focussing lens                                              67


  =G.=

  Glass compressor                                            49
  Glass-Micrometer for the Eye-piece                          73
  Glass plates, ground, clear                                 82
  Glass slides                                               100
  Glass slides, hollow                                       100
  Gypsum and Mica plates                                      99
  Greenough Binocular Microscope                              69


  =H.=

  Haemacytometer after Thoma                                  71
  Handle for holding lens                                     67
  Hand Microtomes                                             97
  Hand Spectroscope                                           71
  Horizontal Microscope                                       56


  =I.=

  Illuminating Apparatus                                      20
  Illuminating Lens                                          100
  Immersion Objective                                     12, 13
  Immersion Oil                                              101
  Iris-diaphragm                                             100
  Iris cylinder diaphragm                                     20


  =K.=

  Knife-carrier                                               93
  Knife-holder                                                97
  Knife after Thoma                                           96
  Knives for Microtomes                                       96


  =L.=

  Lamp                                                        83
  Leather case                                               103
  Lenses:
    aplanatic                                                 67
    binocular                                                 68
    for the pocket                                            68
  Lens for Algae Examination                                  65
  Lens-holders                                                65
  Lens for Projection                                         90


  =M.=

  Magnification                                               13
  Mechanical Stages                                           78
  Megascope                                                   91
  Micrometers                                                 73
  Micrometer Eye-piece                                        73
  Micrometer with squares                                     73
  Micrometer-screw                                            18
  Microscope after Dölken                                     52
    "         "    Nebelthau                                  50
    "         "    Unna                                       33
    "        stereoscopic                                     69
    "        mineralogical                                    57
    "        for dissections                                  62
    "        for reading thermometer scales                  102
    "        for the examination of trichinae                 48
  Microscopical Cases                                        103
  Micro-Spectroscope                                          70
  Microtomes                                                  92
  Microtome knives                                            96
  Moist chamber                                              100


  =N.=

  Nansen's Microscope                                        102
  Nebelthau's Microscope                                      50
  Net micrometers                                             73
  Nose-pieces                                                100
  Notice                                                       4


  =O.=

  Object Marker                                              101
  Objectives achromatic                                       12
    "        apochromatic                                     14
    "        photographic                                     85
  Ocular for Demonstrations                                  101
  Oil-Immersion                                           12, 14
  Opaque illuminator                                         102
  Outfit for Sputum Examinations                             103


  =P.=

  Photographic Objectives                                     85
  Photographic plates                                     82, 85
  Photomicrography                                            82
  Photo-micrographic Apparatus                                82
  Photomicrographic Apparatus with joint for inclination      83
  Pfeiffer dissecting microscope                              64
  Pipettes                                                    70
  Plate holders                                           82, 85
  Pocket Microscope                                           65
  Pocket Lens                                                 68
  Polarizing Apparatus                                        99
  Preface                                                      6
  Projection                                                  87
  Projection Apparatus, large size                            91
  Projection Apparatus after Edinger                          84
  Projection-lamp                                             90
  Projection-lens                                             90
  Projection-ocular                                           91
  Publications                                               104


  =R.=

  Reflector                                                   83
  Revolving Eye-piece                                         15
  Rheostat                                                    90


  =S.=

  Saccharimeter, Mitcherlich                                 102
  Screw-micrometer eye-piece                                  73
  Simple dissecting microscope, wood case, with handrests     66
  Sliding Microscope (Nebelthau's)                            50
  Sliding Microtome                                       92, 95
  Slide for counting the corpuscles of the blood              71
  Spectroscope                                                70
  Stage-Micrometer                                            73
  Stage for Dissections                                       66
  Stand for supporting specimens                              83
  Stand A                                                     24
  Stand I                                                     28
  Stereoscopic Binocular stand                                69
  Stand Ia                                                    30
    "   Ia with English Foot                                  32
    "   Ib                                                    34
    "   II                                                    36
    "  IIa                                                    38
    "  IIb                                                    40
    "  III                                                    42
    "   IV                                                    44
    "    V                                                    46
    "   VI                                                    48
    "    I for Mineralogical Research                         57
    "   II  "        "           "                            60
  Stereoscopic Microscope                                     69
  Swing-out Condenser                                         20


  =T.=

  Thoma's Haemacytometer                                      71
  Thoma Knives                                                96
  Travelling Microscopes                                      53
  Trichinoscope                                               91
  Tube length                                                  8
  Tubeuf drawing Apparatus                                    77
  Turn-table                                                 101
  Türck counting chamber                                      72


  =U.=

  Unna's Microscope                                           33


  =W.=

  Warm Stages                                                 80
  Water-Immersion                                             12
  Welsbach lamp                                               83


  Printed by Fr. Richter, Leipzic.


  =Transcriber's Notes:=
  hyphenation, spelling and grammar have been preserved as in the original
  minor punctuation changes made without notes
  Page 5, and specimens. focal length. ==> and specimens.
  Page 10, will suffice tho show ==> will suffice to show
  Page 15, eye-pieces may he changed ==> eye-pieces may be changed
  Page 17, movement on Stands AI, Ia ==> movement on Stands A, I, Ia
  Page 22, the purpore of modifying ==> the purpose of modifying
  Page 25, in tis central portion ==> in its central portion
  Page 26, has the folloving advantages ==> has the following advantages
  Page 26, is absolutly no limit ==> is absolutely no limit
  Page 43, an excellent loboratory stand ==> an excellent laboratory stand
  Page 47, Exe-pieces I, III. ==> Eye-pieces I, III.
  Page 54, size like the I. b. ==> size like the Ib.
  Page 59, stand with these accessoires ==> stand with these accessories
  Page 61, the and of the tube ==> the end of the tube
  Page 62, The fit inside ==> They fit inside
  Page 64, The case consists ==> The base consists
  Page 68, Aplantic triplets 64-68 ==> Aplanatic triplets 64-68
  Page 69, Magnifikation, 20 diam. ==> Magnification, 20 diam.
  Page 71, micrometric measurment ==> micrometric measurement
  Page 78, Mechanical stage Nr. 98 ==> Mechanical stage No. 98
  Page 85, 42 und 64 mm ==> 42 and 64 mm
  Page 90, removed duplicate 'Transport 250.--'
  Page 91, also wheter it is direct ==> also whether it is direct
  Page 91, a continual, flow ==> a continual flow
  Page 97, 136. Lenght of cutting edge ==> 136. Length of cutting edge
  Page 98, with melled and graduated ==> with milled and graduated
  Page 99, forms port of an ocular ==> forms part of an ocular
  Page 99, any disired position ==> any desired position
  Page 99, The gange measures 0,01 ==> The gauge measures 0,01
  Page 103, light. for illumination ==> light for illumination
  Page 103, 167. Bell jar ==> 177. Bell jar
  Page 107, Stage-Mikrometer, 73 ==> Stage-Micrometer, 73





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