Part 1

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All previous editions of this catalogue are superceded by the present one, which should be exclusively used in ordering.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

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.

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 | | | | | | | | | | | | | |

+----+----+----+---- 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 ==================================================

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=.