DR. F. HORTON ON THE EFFECTS OF CHANGES OF TEMPERATURE 



The increase in period at the larger amplitude corresponds to a decrease in the 

 rigidity modulus of '001 X 10 11 dynes per sq. centim. The value of the logarithmic 

 decrement is seen to increase a little with the amplitude. 



The results of experiments on another iron wire, carried out in the old form of 

 apparatus, the wire alone being surrounded by the heating jacket, gave as the modulus 

 of rigidity at 15 C. 15 = 7 '9656 X 10 n dynes per sq. centim., and for the " temperature 

 coefficient" at 15, ft = '0006047. 



The wire used was exactly similar to the one the experiments on which have been 

 described above, being a pure soft iron wire annealed in the same manner. The large 

 difference between the values of ft found for the two wires is most probably due to 

 the imperfect method of experimenting used in this case. 



Platinum. 



A pure platinum wire was used. The periods given in the following table are in 

 all cases the means of several observations. 



