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SUMMARY OF CURRENT RESEARCHES RELATING TO 
(1) Apparatus for instantaneous photomicrography. — The author 
strongly recommends the use of the finder, with which it is possible to 
view simultaneously the preparation on the stage of the Microscope, and 
the projection of the image on the ground glass of the camera. The 
apparatus employed is a modified form of the Bourmans system. The 
camera is of wood, 30 cm. by 30 cm. and 12 cm. deep. On the front is 
a board, sliding in grooves, on which a metal flange with circular 
aperture of 5 cm. is screwed. A short tube carrying a shutter is 
attached to the flange. On this tube is screwed a totally reflecting 
prism in a circular metal box, having a right-angled tube of less diameter, 
to which is applied a stereoscopic binocular eye-piece of Abbe-Zeiss. 
The two eye-pieces of the latter are unscrewed and replaced by two 
other tubes. The tube replacing the straight eye-piece is of the same 
length, and can be fitted with slight friction into the socket of the 
vertical tube of the prism-box. The other tube replacing the inclined 
eye-piece has a rack and pinion motion, and can be lengthened by the 
addition of other pieces of tube of the same diameter. The finder 
having been arranged, the tube of the stereoscopic eye-piece is placed in 
that of the Microscope, and by a strong binding screw the foot of the 
instrument is fixed to the work-table. A special slide, which serves the 
triple purpose of plate-holder, support for the ground glass, and shutter, 
consists of a square box, provided with two cylinders, on which is rolled 
a band of black sheet indiarubber completely light-proof. A screw 
button presses on the spring, which by a pneumatic release sets the 
cylinders in motion. On drawing a silk thread, the indiarubber sheet 
unrolls itself on the cylinders and, traversing with great rapidity the 
free surface of the slide where the sensitive plate is exposed, returns 
instantly to its first position. The maximum rate of passage of the 
indiarubber band was 1/20 of a second. Since the shutter is placed at 
the back of the camera, the shock of its release can only very slightly 
affect the Microscope. 
The author in all his experiments made use of the large Microscope 
of Koritska, and considers that the apochromatic objectives supplied to 
him by this maker are in many respects superior to those of Zeiss. The 
polarization apparatus is disposed as in the Nachet petrographical model. 
The micrometer screw has a divided head and reads to the 500th mm. 
with great exactness. For very delicate work the author used the stand 
(large model) of Powell and Lealand, or a Boss stand with swinging 
tail-piece for oblique light. When powerful condensing systems were 
used, a special cell containing a saturated solution of alum was placed 
beneath the stage, and the rise of temperature was noted by a ther- 
mometer. 
The indispensable condition for success with a high-power objective, 
as e.g. a 1/25 immersion, is to have a sufficiently strong illumination. 
To a bad illumination of the image the author attributes most of the 
faults usually noticeable in photomicrographs. 
(2) Apparatus for the reproduction of consecutive movements of 
microscopic creatures. — Experiments made by the author with one of 
the first photographic cameras of Stirn succeeded sufficiently well 
to induce him to make it the basis of the apparatus which he subse- 
quently employed. This camera consists of a circular box, 2 cm. thick, 
