5- On a Demonstration Apparatus for determining 



Young's Modulus. 



By Gouripati Chatterjee. 



This apparatus was primarily designed for showing quali- 

 tatively to a class the elongation of metallic wires when loaded. 

 Later on it was found to be sufficiently accurate for use as a 

 demonstration apparatus with which load-elongation curves 

 could be actually plotted before an audience, and values of 

 Young's Modulus obtained rapidly to within 1%, provided the 

 radius of the wire was determined with the usual precautions. 

 The use of an optical method for finding Young's Modulus 

 is not new and was used by Bottomley, 1 Ewing, and others, but 

 the apparatus designed by those observers was very much more 

 elaborate than the one here described and was intended for 

 accurate laboratory determinations. 



Fig. L 



1 Phil. I, Mag. 889, Vol. 28, p. 94 



