46 THE CAMERA, ETC. 



the lamp ; an aperture six inches square being pre- 

 viously cut in it, on a level with the top of the plat- 

 form to which the camera is attached. This aperture 

 enables direct sunlight to be used, with the appara- 

 tus in the horizontal position. 



A division about a quarter of an inch wide, runs 

 along the centre of the plank to within two or three 

 inches of its extremities, this enables the lamp, bull's 

 eye condenser, and sulphate of copper cell to be 

 firmly clamped in position by binding screws. 



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 24, 26, 28, 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, 

 but 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 



