588 



SUMMARY OF CURRENT RESEARCHES RELATING TO 



of the repeating-back. For the exposure through the green filter the 

 frame and slide are pushed to the left hand until the pin of a spring 

 latch drops into a depression in the colour-filter frame. For the blue 

 filter exposure the colour-filter frame and dark slide are pushed com- 

 pletely over to the left. 



Fig. 118. 



Buxton's Photomicrographic Apparatus.* — The great feature in 

 this arrangement (fig. 119) is that the table which carries the optical 

 bench is made to revolve. This allows the operator to sit comfortably 

 on a stool and make the rough focussing. This table is then swung 

 into place, and the camera, on a second (fixed) table, is then adjusted. 

 The separation and combination of tables renders necessary some 

 special means of coupling the focussing rods of the fine adjustment, and 

 the following method is adopted: — On the table of the optical bench, 

 directly beneath the fine adjustment head of the Microscope, is situated 

 a milled wheel on suitable standard, and a belt from this wheel extends 

 to the fine adjustment head of the Microscope. Through the axis of the 

 wheel is located a rod carrying at the end towards the camera a clutch 

 which can be quickly connected with the focussing-rod of the camera by 

 sliding adjustment operated by a milled head. The optical bench must, 

 of course, be brought to its proper position with relation to the camera 

 in order to make this connection, and for this purpose a lever, shown in 

 the illustration, is provided. 



Sanger, Shepherd, & Co.'s Filters for Photomicrography. — 

 Fig. 120 shows this apparatus. The filters are made to order for any 

 double stain in bacteriological work, so as to photograph the stains 

 either in black or white. The green filters are especially recommended 



* Journ. App. Micr., 1901, pp. 1366-72 (7 figs.). 



