Intelligence and Miscellaneous Articles. 



219 



the resistance was measured almost simultaneously with the passage 

 of the current, the rise in temperature could be very exactly 

 known, and the effect of radiation could be very easily determined. 



Combining equations (1) and (2), we have 



J=™S 



(r+S)a/J 



E, as measured by the electrometer, was about one volt, = 10* 

 C.Gr.S. units. H was '171 ; r, the resistance of the ballistic 

 galvanometer, was 3296 ohms ; S 15 the shunt, was 1025 ohms ; T, 

 the time of a single vibration of the needle, was 12*6 sec. ; a, the 

 resistance of the strip at 0°, was 1*072 ohm; /3 was '00503, the 

 weight of the strip was -230 gr. ; its specific heat, -1 14 ; the gain 

 in resistance of the strip was -05 ohm, and <5, from 20 experiments, 

 was 2&8 cm. : G was 769'4 for ?=1. 



J = 



10 s x -171 x 12-6 x 26-8 x 4-321 x 1-072 x -00503 

 769-4 7T -05 x 1*025 x -230 x '114 



= 4-14 x 10 7 ergs per gram-degree. 



In Joule's experiments, the process of heating was continued for 

 nearly an hour, whereas here it lasts for less than a second. In 

 the former method, it was necessary that the current should remain 

 sensibly constant throughout the experiment, and the calorimeter 

 was radiating heat throughout that time. In the short time 

 required by the latter method, the radiation must be very small, 

 and the error from the inconstancy of the curent is avoided. I 



