the Investigation of Young's Modulus for Wires. 



545 



of the wires. By using No. 20 b.w.g. wire the length 

 employed was satisfactorily reduced to 10 cm. This was 

 enclosed in a chamber of thick copper, and heating was 

 attempted by means of a flat platinum coil at the bottom, but 

 this was unsatisfactory and was abandoned — probably on 

 account of convection-currents. 



Fur. 6. 



10 S3 x/O' 



<0 



si 



I 



J 



8-etx/o' 



2-800 



20-832 



/nitiat Load in ftitogr. 



The method finally adopted was one in which the constancy 

 of boiling-point of a liquid at a definite pressure is made use 

 of. This involved some changes in construction of the 

 apparatus, the final form of which will now be described. 



Fte. 7. 



At the top and bottom are the two stretching-disks D 1 and 

 D 5 (see fig. 7, Di is not shown), of gun-metal, 5-£ inches in 

 diameter and \ inch thick, each with three radial slots of 



