540 FOURTH REPORT — 1834. 



Names of Bodies, with their Elasticities. g^^'j^Jgl'^t^. Elas?id«es. ="°"- 



Ivory (-81) against lead (-20) -39 -44 — ^ 



Ivory ('81) against brass (-41) '76 "78 — -sV 



Ivory (-81) against bell-metal (-67)... -79 -77 -^ 



Brass (41) against bell-metal (-e?)... -53 -55 —-^ 



Brass (-41) against cast iron (73) ... '52 -50 ^ 



Brass (-41) against steel (-67) '47 -47 ..; — 



Brass (-41) against limestone* (-79) . -71 '73 — 3^ 



Lead (-20) against limestone (-79) ... -32 -28 J- 



Lead (-20) against elm t (-60) -37 -41 — ,-V 



Brass (-41) against elm (-60) -58 -52 ^ 



Other instances might be adduced, but the above may be 

 sufficient to show the consistency of the formula, and of the 

 7th Conchision, from which it is deduced. 



* I have supposed the modulus of limestone to be 2,520,000 lbs., the same 

 which Mr. Tredgold found for white marble. The balls we used were some- 

 what softer than it ; but Mr. Tredgold's results being obtained from the flexure 

 at the time of fracture, must be too low, as he himself has observed. 



f I have assumed the modulus of elm, struck across the fibres, to be 

 1,000,000 lbs.; its value in the direction of the fibres being 1,340,000 lbs., as 

 before given. 



4 



