134 



Prof. H. F. Weber on Electromagnetic and 



Date. 



J. 



December 21, 1876 19-8 



}) 



22, „ 



V 



23, „ 



V 



24, „ 



V 



25, „ 



V 



26, „ 



V 



27, „ 



•)"> 



28, „ 



?; 



29, „ 



;; 



30, „ 



JJ 



31, „ 



January 1, 1877 





metre-kilograms. 



19-8 



428-36 



19-7 



430-31 



18-7 



426-37 



18-8 



427-50 



18-8 



427-45 



20-0 



429-18 



20-1 



428-02 



19-9 



429-87 



19-4 



430-15 



19*7 



426-93 



19-5 



427-90 



19-6 



428-96 



According to this the mean mechanical equivalent 'of the heat- 

 unit is equal to 428*42 metre-kilograms (with the probable 

 error ±0*25), the specific heat of water at the mean tempe- 

 rature t a =19°-5 employed being put =1. 



In a third series of experiments the period and the current- 

 intensity were chosen such that the rise of temperature in the 

 calorimeter amounted, as in the previous experiments, to about 

 15°. The proportions, however, were not so closely limited 

 as to make the difference t—t a as small as possible ; rather a 

 play of a few degrees was given to it. The results of this 

 series, in which the exchange of heat between the calorimeter 

 and its environment possessed a value four or five times as 

 great as in the previous series, were : — 



ta. 



Date. 



March 28, 



5? 



29, 



?? 



30, 



?J 



31, 



April 



1, 



V 



2, 



?? 



3, 



V 



4, 



}) 



5, 



J? 



6, 



J? 



7, 



?? 



8, 



J. 



1877 



o ' 



netre-kilograms. 



16-1 



427-15 



16-6 



429-30 



16-8 



429-61 



17-3 



428-03 



17-0 



426-92 



17-7 



428-56 



18-3 



427-91 



18-0 



429-10 



17-7 



427-85 



18-9 



427-52 



18-5 



428-43 



17-9 



428-93 



According to this series the mean value of the mechanical 

 equivalent of the unit of heat is 428*28 metre-kilograms (with 

 a probable error of ±0*18), the specific heat of water, at the 

 mean temperature t a =17°-6 employed, being put =1. 



