Apparatus for Photomicrography. By I), de Orueta. 591 



The illuminating apparatus is mounted on a triangular optical 

 bench F, of 0*5 m. (19^ in.) length, permitting exact centring 

 and focus. This bench stands on a wooden desk, which can be 

 inclined in all positions between the vertical and 50° 



The illuminating system used by the author is composed of a 

 Nernst lamp, N, a support, T, for coloured glasses, or liquid filters 

 of different classes, and a collector, L (" bullseye ") with an iris 

 diaphragm. In order to reduce the intensity of the light for direct 

 observation, one or more white ground glasses are put on the 

 support T. These must be removed when the photograph is about 

 to be taken. 



With this apparatus photographs can also be taken when the 

 Microscope is in the horizontal or vertical position. 



In the former case the camera axis must be placed in continua- 

 tion of the axis of the Microscope. In the latter, the situation of 

 the bar B must be changed, sliding it directly inside the column 

 C* The apparatus then becomes the vertical camera, figured in 

 Zeiss's catalogues. 



The author has made many photomicrographs with this ap- 

 paratus, among them several of very difficult diatoms at 1200 

 diameters (with an apochromatic objective of 1-4KA.), and the 

 results have always been very satisfactory. The price of the 

 apparatus is very low compared with the price of the large photo- 

 micrography installations. 



* It is better, however, to haye an additional B bar. 



2 q 2 



