1887.] Stress and Strain on the Properties of Matter. 363 



the greatest care to wires of piano-steel, copper, platinum- silver, silver, 

 and platinum. The wires of copper, silver, and platinum were obtained 

 from Messrs. Johnson and Matthey as chemically pare. 



The same wires were also tested for the value of the modulus of 

 longitudinal elasticity by the method of longitudinal vibrations. In 

 this method the wires were fixed at both ends, and corrections, which 

 are fully described in the paper, were made for the want of rigidity 

 in the supports at the ends. The same method served for deter- 

 mining the velocity of sound in the metals piano-steel, iron, copper, 

 German- silver, platinum-silver, silver, and platinum, with considerable 

 accuracy. The following two tables give the results obtained : — 



Table I. 



Metal. 



Condition. 



Density. 



Telocity of sound in 

 metres per second. 



German-silver .... 

 Platinum- silver . . . 





7-7475 



7- 6831 



8- 8976 

 8-6320 



12-1900 

 10 -4668 

 21 -0500 



5198 

 5096 

 3958 

 3860 

 2804 

 2801 

 2750 



Table II. 



Metal. 



Condition. 



Young's modulus in 

 grams per sq. cm. 

 as obtained by 

 the kinetical 

 method. 



Ditto, as obtained 

 by the statical 

 method. 



e,. 





Piano-steel . . . 



Unannealed . 



2133 x 10 6 



2140 x 10 6 



0-997 





>> 



1316 



1323 



0-995 







1622 



1623 



1-000 



Platinum-silver 





997 



1001 



0-996 





55 



835-6 



828-6 



1-008 











0-999 



Four of the wires used in the experiments on longitudinal elas- 

 ticity were also tested for torsional elasticity, both by the method 

 of statical torsion, and by the method of torsional vibrations. The 

 diameter of each of the wires was about 1 mm., and the lengths 

 varied from 650 to 800 cm., thus even with very small torsional defor- 



