110 



AKUANGEMKNT OF Al'I'A RATUS, ETC. 



Fig. 26. 



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ficial light, and which re- 

 quire high powers for their 

 -^j resolution. We shall con- 

 fine ourselves to the \ inch 

 objective. The apparatus is 

 considered as still remaining 

 in the position adopted in 

 our first experiment. 



The lamp stand, and bull's 

 eye condenser, are clamped 

 in their original position by- 

 binding screws fitting in the 

 division running down the 

 centre of plank no. 3. 



The camera legs are short- 

 ened to allow of the up- 

 right division no. 1 and no. 

 2 assuming the horizontal 

 position, but need not be 

 removed (they are omitted in 

 the figure) . The side board 

 is detached, and replaced 

 twoboltslowerdown. When 

 firmly screwed on, it keeps 

 all three divisions of the 

 plank perfectly rigid, and 

 in a straight line with each 

 other. 



The camera and sulphate 

 of copper cell are removed ; 

 Swan's incandescent lamp 

 substituted for the parafin, 



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