116 



PEACTICAL PHOTO-MICBOGBAPEY 



form one unit, yet it is open to practically the same objections 

 as the previous one, the camera itself being rather liable to 

 vibration owing to its method of support. While it is a very 

 useful form of apparatus for ordinary laboratory work, it should 

 not be used in preference to a more stable horizontal form, 



since it is designed chiefly for 

 obtaining photographic records 

 of researches. 



Where a combined vertical 

 and horizontal camera is for 

 any reason the most con- 

 venient, then one in which 

 there is on either side a support 

 for the frame carrying the 

 focussing-screen is preferable ; 

 the apparatus is then not 

 so liable to respond to ex- 

 traneous vibration, and is 

 much less liable to movement 

 while making any adjust- 

 ment. Fig. 39 illustrates a 

 convenient and efficient form 

 of this arrangement. The 

 baseboard is stout, and 

 the uprights on either side 

 are rendered firmer by two 

 struts that come from the 

 baseboard to a point approxi- 

 mately halfway up the side- 

 stays. The focussing-screen 

 is adjustable in grooves, and 

 can be raised or lowered and 

 clamped in any position within 

 the range of the apparatus. 



FIG. 39. Combined Horizontal and 

 Vertical Camera. (W. Watson & 

 Sons.) 



A shutter is provided in the position B, although this addi- 

 tion is for most purposes superfluous. Better results would 

 probably be obtained if this shutter were not included, 

 since any arrangement for cutting off the light should be inde- 

 pendent of either camera or microscope. The bellows of the 

 camera give an extension of 20 inches, which is ample for any 



