38 



Mr. W. Sutherland on a 



3. Compilation of Data as to Absolute Values of Rigidity at 

 Ordinary Temperatures (between 0° and 20°) . 



The sources of these data are, in addition to those men- 

 tioned in the last compilation, Kupffer {Mem. de V Acad, des 

 Sc. de St. Pe't. 6 ser. t. v.), Tomlinson (Phil. Trans. 1883, 

 and Proc. Roy. Soc. xlii.), Sir W. Thomson (Encyc. Brit. 

 art. Elasticity), and Kiewiet (Wied. Ann. xxix.). 



The rigidity is given in grammes weight per square centi- 

 metre. 



Table IT. 



Metal. 



1 



n/W>. 



Authority. 



■ Metal. | 



52/10°. 



Authority. 



j 



Copper 



390 ! 



i 

 Kohlrausch and 



Aluminium (it) 



234 



Pisati. 







Loomis. 





250 



Tomlinson. 





397 



Pisati. 





267 



Tomlinson. 





441 



Tomlinson. 





241 



Thomson. 





420 

 457 



Tomlinson. 

 Tomlinson. 



Tin 



121 

 150 



Tomlinson. 

 Kiewiet. 





(mean of many) 



449 



Thomson. 



(hammered) 



109 



Sutherland. 





440 



Kiewiet. 



(pipe) 



157 



Sutherland. 



Copper (m) 



436 



Pisati. 



Lead 



74 



Tomlinson. 



Silver 



283 



Kupffer. 





89 



Sutherland. 





257 



Pisati. 





88 



Sutherland. 





272 



Tomlinson. 



Iron 



742 



Kupffer. 





270 



Thomson. 





713 



Kupffer. 



Silver (u) 



331 



Pisati. 





694 



Kohlrausch. 



Silver («) 



276 



Tomlinson. 





811 



Pisati. 



Gold 



271 



Kupffer. 





773 



Tomlinson. 





281 



Thomson. 





751 



Tomlinson. 



Gold(«) 



265 



Pisati. 





766 



Tomlinson. 



Magnesium ... 



172 



Tomlinson. 





790 



Thomson. 





130 



Sutherland. 



Nickel 



758 



Tomlinson . 



Zinc (u) 



340 



Tomlinson. 





637 



Kupffer. 

 Pisati. 





360 



Thomson. 





628 





380 



i Kiewiet. 





I 693 



Tomlinson. 



Zinc (rolled 



311 



Sutherland. 





662 



Tomlinson. 



anneal.) 









622 



j Thomson. 



The discrepancies in this table must be due mainly to 

 differences in purity and elastic state. But on taking the 

 mean of the above values for each element we must obtain 

 values near to the true ones at 15° ; these are now given. 



Table III. 

 Mean values of 10~ 6 times the Rigidity at 15° C. 



Cu. 



Ag. 



Au. 



Mg. 



Zn. 



Al. 



Sn. 



Pb. 



Fe. 



Ni. 



Pt. 



430 



280 



270 



150 



350 



250 



135 



84 



750 



760 



650 



