CH. VII] PHOTOGRAPHING WITH THE MICROSCOPE 219 



The photo-engravers have overcome vibrations by suspending 

 their cameras, or using spring coils as a part of the support. In case 

 of real need this method would serve the photographer with the micro- 

 scope. The whole apparatus must be suspended or supported on 

 springs, so that any vibration will be equal for all parts. The small 

 table and vertical camera lend themselves to either suspension or 

 support on a platform with spiral springs, or the microscope and 

 camera can stand directly on the platform (fig. 130). 



FIG. 130. PLATFORM WITH SPIRAL SPRINGS FOR THE CAMERA TO NULLIFY 

 VIBRATIONS IN PHOTOGRAPHING. 



342. Arrangement and position of the camera and the micro- 

 scope. For much photo-micrography a vertical camera and micro- 

 scope are to be preferred. Excellent arrangements were perfected 

 long ago, especially by the French. ('See Moitessier). 



Vertical photo-micrograph ic cameras are now commonly made, 

 and by some firms only vertical cameras are produced. They are 

 exceedingly convenient, and do not require so great a disarrangement 

 of the microscope to make the picture as do the horizontal ones. The 

 variation in size of the picture in this case is mostly obtained by the 

 objective and the projection ocular rather than by length of bellows. 

 It must not be forgotten, however, that penetration varies inversely 

 as the square of the power, and only inversely as the numerical aper- 

 ture ; consequently there is a real advantage in using a lo\v power of 

 great aperture and a long bellows rather than an objective of higher 

 power with a short bellows. A horizontal camera is more convenient 

 for use with the electric light also (fig. 131). 



