420 



DU. F. HORTON ON THE MODULUS OF TORSION AL KlfJIDITY OF 



value, but is slightly greater than it was before heating. After the heating to 

 55 C. the modulus at the ordinary laboratory temperature seems to have attained a 

 constant value ; for the values obtained after this, on being corrected for the small 

 differences of temperature, are all in very good agreement. 



In Diagram I. the mean value of the modulus of rigidity at each temperature is 



304 



3-02 



/ 



SO 40 jo 5 " 60 70~ 



Temperature Centigrade. 



90 5 too 



Diagram I. Showing alteration of modulus of rigidity with change of temperature. 



plotted against the corresponding temperature. It will be seen that, with the 

 exception of the mean of the first three observations at the ordinary temperature of 

 the room, the points lie on a straight line. 



The first few heatings probably have an annealing effect on the fibre, and assist it 



