Microscopes and Accessory Apparatus Part 12

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 2424 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 gla.s.s plate, etc., without microscope stand =60.--=

[Ill.u.s.tration: Photo-micrographic Apparatus No. 109.]

=Edinger's Projection Apparatus.=

[Ill.u.s.tration: Edinger's Projection Apparatus with Nieser's Photographic Camera.]

110. =Edinger's Projection Apparatus=--For projecting and drawing large objects slightly magnified. (Cf.

Zeitschrift fur 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 912 cm and 1318 cm =38.--=

112. =Larger Projection Apparatus with Camera= for plates 912, 1318, 1824 and 2430 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).

[Ill.u.s.tration: 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 Amperes 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 k.n.o.bs conveniently situated as shown in the ill.u.s.tration.

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.

[Ill.u.s.tration]

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 ill.u.s.tration 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.

[Ill.u.s.tration]

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 910 and 912 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 Amperes, with centering arrangement =92.--=

=Fixed rheostat= =30.--=