162 



EXPERIMENTS AND INVESTIGATIONS 



PLATE XIV. 



c 



Is the instrument by which, is tried the experimentum crucis 

 on the action of the third edge, and also the experiments on 

 the distances of the edges as affecting the disposing force. 

 G is the groove in which the uprights H, I, K move. There 

 is a scale graduated, F, by which the relative distances can 

 always be determined of the plates A, C and B. A moves up 

 and down upon H, B upon I, and C upon K ; each plate is 

 moved up and down by rack and pinion D. The uprights 

 also move along the groove G by rack and pinion E. 



