380 Temperature Coefficient of Young's Modulus. 



The values of the average temperature coefficient of Young's 

 modulus (regarding the variations as linear) are given in 

 Table III., together with data obtained by other observers. 



Table III. 



Author. 



Temp. Eange. 



Temperature 



Coefficient of 



Young's 



Modulus. 



Remarks. 



Gray 1 , Blyth, & Dunlop. 

 Shakespear 



15 to 100 

 13 to 100 



8-4 to 60 

 to 50 



-0-000197 



-00004 



-00001 



-00002 



-0-00067 



-o-ooou 



-0-00023 



-0-0005 



-0-00013 



-000033 



-00007 



-0-00098 



-0-00098 



Soft iron. 



Soft iron. 



Iron. 

 Iron. 



Piano wire. 

 Electric heating. 

 Ordinary heating. 



Soft iron annealed . 

 Ditto, unannealed 



and hardened by 



stretching. 



Slotte 



Pisatis 



KatzenelsohnS 



Noyes 



to 100 

 15 to 180 

 26 to 116 





17-5 to 129 

 20 to 600 

 30 to 70 



H L Dodge 4 



Harrison & Chakravarti. 



i 

 i 



i Gray, Blyth, and Dunlop, Proc. R. S. Lond. vol. lxvii. p. 180(1900). 



2 Pisati, Gaz. Chim. Ital. vol. vii. p. 1 ; Nuovo Cimento (3) iv. p. 152 

 (1878), and v. p. 34 (1879). 



3 Katzenelsohn, Beibliitter, xii. p. 307 (1888). 



4 Dodge, Physical Review, 2nd series, vol. v. No. 1. 



The value of the temperature coefficient found by the present 

 writers is about double the mean of the values given by 

 previous observers. In judging this result regard should be 

 had to the wide variation which exists among the data hitherto 

 available. It should also be borne in mind that most of the 

 values of the temperature coefficient quoted depend on two 

 or three values of the modulus instead of upon 20 or 30, 

 as is the case in the present investigation. In view of the 

 number and consistency of the results, the authors feel 

 confidence, not only in the correctness of the temperature 

 coefficient given above, but also in the belief that there is no 

 maximum in Young's modulus during electric heating, at 

 least for the particular specimen of iron wire which was 

 examined. 



Baker Physical Laboratory, 

 Presidency College. 



