46 HAND AND OTHER APPARATUS. 



The stand can be placed at any angle, by shorten- 

 ing or lengthening the camera legs attached to the 

 bolts on the extremity of plank No. 1. They may be 

 detached when not required. 



A reference to figures (23, 24, 25), will enable us 

 to understand why the arrangement is so compli- 

 cated. It will be seen that five different methods of 

 placing the apparatus are adopted, and the stand 

 made to suit them all. A full description is reserved 

 for another portion of the work, devoted to the 

 particular arrangement of the stand, with certain 

 objects and objectives. 



Those positions in which the apparatus is hori- 

 zontal should always be chosen if possible, not only 

 because it is the most convenient for manipulation, bub 

 on account of the superiority of the illumination. 



The perpendicular position is only necessary when 

 the object is fluid, and the positions between these 

 when oblique light is required. 



An iron rod three feet long, sliding in a tube be- 

 neath the oblong board supporting the camera, is 

 fixed so that a wheel, attached to the extremity 

 next the microscope, may always occupy the same 

 position beneath the fine adjustment, indepen- 

 dently of the distance of the camera from the plat- 

 form. A silk cord fastened round this wheel and 

 the fine adjustment, enables an observer, by turning 

 the milled head at the opposite end of the rod, to 

 focus the ima« - e on the screen of the camera when 



O 



the adjustment is beyond reach. An assistant, is 

 then unnecessary as no matter how intelligent he may 



