ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 



69 



edges and corners, makes an exceptionally neat case, 8| in. by 6 A in. 

 by 8f in. in its extreme over-all dimensions. The Microscope is rigidly 

 held in place in the case by two strong pins, which fit into depressions m 

 the arm. To prepare for using, it is only necessary to lift the instru- 

 ment from the case, turn the legs to position and pull the draw-tube. 

 Tin- instrument goes into the case with the objectives in position on the 

 •nose-piece. Caps are furnished for protecting the objectives if desired. 

 The instrument, a simple side fine adjustment, each division of the 



Fig. 5. 



graduated button of which represents a movement of one micron in the 

 body tube. Fig. 5 shows the open case, the mechanical stage and 

 camera-lucida being in position. 



(4) Photomicrography. 



Freedom from Vibration for Photomicrography.* — The apparatus 

 described below has been in use in the Office of Soil Bacteriology 

 Investigations for many years, and has made it possible, says K. F. 

 Eellerman, to prepare photomicrographs of unusually high character, 

 requiring sometimes as much as six minutes exposure, even though tram 

 cars and heavy wagons pass the doorway of our building at frequent 

 intervals. The stand consists essentially of a heavy stone slab A, upon 

 which is mounted the photomicrographic equipment and the electric 

 lighting apparatus. Immediately below this stone and supporting it is 



Dep. Agric. U.S.A., Bureau of Plaut Industry. 



