Glass, and Metal Wires subjected to Constant Pull. 525 





X. 



log*. 



x— 456-7 



log* 





458 



•09 



14-4 





459 



•14 



16-4 





460 



•20 



165 





461 



•26 



165 





462 



•33 



16-1 





463 



•39 • 



162 





463-5 



•41 



166 





464 



■45 



162 





4645 



•47 



16-6 





465 



•50 



166 





465-5 



•53 



166 





466 



•56 



16-6 





466-5 



•59 



16-6 





467 



•63 



164 





4675 



•66 



164 





468 



•69 



164 



As the screw was turned the readings in the telescope and in 

 the gauge were taken : — 



Scale. 



Micrometer. Scale. 



Micrometer. 



Scale 

 Difference. 



Micrometer 

 Difference. 



1371 

 2175 

 299-0 



3798 

 4614 



12-50 5436 

 13-00 6260 

 13-50 7094 

 1400 7940 

 1450 8799 



150 

 15-5 

 160 

 165 

 170 



406-5 

 408-5 

 4104 

 414-2 

 4185 



2-5 

 2-5 

 2-5 

 25 

 25 









2058-1 



125 



.•. 1 scale-division = '00608 cm. 

 Expressing everything in absolute units we have 

 Load per sq. cm. cross section = 604 kilos, 

 and when x is measured as stretch per unit length 

 £ = •000351. 



Exactly the same process was gone through with different 

 copper wires from the same coil. They were annealed with 

 the same current (12 amps.) for the same time (5 mins.),and 

 then their curves of stretching with various loads were 

 obtained. It appears that the logarithmic law obtains right 

 up to the load which causes the wire to pull out quite rapidly 

 and break. 



The following is the series of values of h which was obtained 

 for this particular coil of copper wire treated in this manner. 



