MR. BEVAN ON THE MODULUS OF TORSION. 
131 
Talbe of the modulus of torsion of Metals. 
Specific 
gravity. 
Modulus of 
Torsion. 
Pounds. 
Iron, English (wrought) . 
Iron, English (wrought) . 
Iron, thin hooping. . . 
Steel 
Steel 
Steel 
Iron cylinder .... 
Iron cylinder .... 
Iron square 
Iron square 
Iron square 
• 
1810000 
1740000 
1916000 
1984000 
1648000 
1618000 
1910000 
1700000 
1617000 
1667000 
1951000 
Mean of Iron and Steel 
1779090 
Iron, Cast 
Iron, Cast 
Iron, Cast 
940000 
963000 
952000 
Mean of cast-iron . . 
7.163 
951600 
Bell-metal 
8.531 
818000 
On comparing these numbers with the modulus of elasticity of the same 
substance, I find the modulus of torsion to be T Vth of the modulus of elasticity 
in metallic substances. 
