L89L] 



Young s Modulus for Crystals, $c. 

 FIG. 2. 



381 



- cross section of 



beam 



abe carrying the oblique arms B, B'. On B is mounted the tele- 

 3ope T, and on B' the collimator C, having in its principal focus the 



iss scale S. 



and K 3 are two parallel horizontal knife edges, mounted on a 



iss support at the upper end of A. On these knife edges the sub- 



ince to be examined rests, and a third knife edge, K 3 , parallel to 



le other two, and half-way between them, Avhich. is properly guided 



rnd free to move only in the vertical plane passing through its edge, 



cesses on the substance with a force determined by the magnitude 



the weight W and its position on the graduated arm D. 



