106 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
In order to pass conveniently from observation through the apparatus 
to observation through the free eye-piece, the prism, with its diaphragm 
arrangement, can be rotated to one side about a vertical pin Z. The 
return of the prism to the central position is marked by a spring-catch. 
To obtain on the table an image of moderate size quite free from dis- 
tortion, such an extent, and thereby weight, would have to be given to the 
side arm carrying the mirror, and to the mirror itself, as would be quite 
incompatible with the proper working of the apparatus. A moderate 
length, therefore, of 10*5 cm. was given to this arm, which was made of 
aluminium, while the size of the mirror was 7 to 8 cm. long and not 
much more than 5 cm. broad. To obtain drawings free from distortion, 
in combination with this apparatus a drawing table, similar to that 
described by Bernhard,* must be used. 
Improved Form of Bernhard' s Drawing Desk.j — Dr. W. Bernhard 
has introduced the following changes in his desk for microscopical draw- 
ing which was described in this Journal for 1893, pp. 782-3. 
(1) The drawing plate has, instead of the earlier swallow-tail groove, 
a very exactly worked brass groove on the upper plate, so that any 
shifting of the plate is prevented. 
(2) The arrangements for determining the necessary height and in- 
clination of the drawing board have been modified. The guiding arc on 
the left frame has now a division in 5°, while the edge of the right 
frame is provided with a centimetre scale, on which a pointer attached to 
the movable slide of the frame is adjusted. 
(3) An adjustable rest for the drawing arm has been added to the 
instrument. This rest is connected with the drawing plate by a hinge, 
and is supported by a hinged piece, which is capable of extension, and 
has its lower end resting against the base-plate of the apparatus. By this 
arrangement the rest can be used in any position of the table, and can be 
folded down upon the drawing plate w 7 hen the apparatus is not in use. 
(4) For convenience in drawing an arrangement has been added by 
which the Microscope and drawing plate can be inclined towards the 
drawer. For this purpose the apparatus is connected by two hinges in 
front with a solid base-plate, so that the whole drawing table, with the 
Microscope, can be inclined towards the observer, and fixed at any 
inclination by a clamping screw. 
A Silver on Glass Camera Lucida.J — Mr. W. Forgan gives a descrip- 
tion of the various drawing apparatus which have been devised for the 
Microscope, and speaks of the difficulties experienced by many in their 
use. The method which he proposes is to place a small silver on glass 
mirror, such as is used as a flat in the Newtonian telescope, on the eye- 
piece of the horizontal Microscope, and so project the image down on 
the paper lying on the table. 
(4) Photomicrography. 
Photomicrographic Apparatus. § — Prof. M. Lavdowsky’s apparatus 
reminds one of that of Reichert, but differs from it in many respects, 
* See this Journal, 1893, p. 782. 
f Zeitschr. f. wiss. Mikr., xi. (1894) pp. 289-301. 
X Proc. Scottish Micr. Soc., 1893-4, ppJ122-9. 
§ Zeitschr. f. wiss. Mikr., xi. (1894) pp. 313-20. 
