386 



Mr. A. Mallock 



[May 27, 



r*»If the variations of Young's Modulus depended solely on the 

 melting point, the assumption might be stated in the form — 



Young's Modulus at temperature 6 1 absolute is to that at 2 as 

 $! is to 2 , so that if < 



0° C. and 6 2 = - 273 



E0°C. 



E - 273° C. 



Melting point Centigrade 

 Melting point Centigrade +" 273° C. 



In the full curve represented in the slide (8) the ordinates give 

 the variations of Young's Modulus for a metal whose melting point 

 (absolute) is indicated by the abscissa, calculated from the equation. 

 (Fig. 3.) 



y 



For tk Full Urn. I a Mfelfrrtj fr.tnt.A<,«,Ur, 



— young i Modulus -t AOsclixte. 2*r<* 



on Wit aitm-mpfti* thdt /5ft t*»'«dt«'««/ «• /*• 

 /Modulus uitfi T»m/>*r<yture aur*. lil*t+r 



fit* *>«/' //;tu/ /£ ra.Cios 



UK. 

 „ .f., .. 



505" 



iooo (500 3555 



Absolute Ttm^eratuPt 



"33O0- 





Fig. 3. 



The circles show the variations actually found for the various 

 metals above-mentioned, and though it is evident that something 

 beside the melting point influences these results, the experimental 

 points do show a tendency to follow the curve, though the variations 

 found by trial are generally in excess of those estimated. 



Young's Modulus being a complex quantity, depending both on 

 rigidity and compressibility, I thought it would be of interest to try 

 experiments in which rigidity only was involved, and this was done 

 by timing the torsional vibrations of test-pieces in the form of wires 

 or very narrow strips of plate. 



The apparatus used is shown in the slide (9). A vertical rod 

 suspended by a long fine wire carries a cross-arm weighted at both 

 ends, to increase its moment of inertia ; the test-piece is clamped to 



