470 On the Heating Effects of Electric Currents. [Apr. 3, 



Constant deflection from standard Daniell cell=9050'. 



Description of wire. 



Gauge of wire in 

 mils. 



Area per square 

 inch. 



Deflection. 



Shunt. 



Resistance in coils. 



Resistance of shunted 

 galvanometer. 



Total resistance. 



Equivalent deflec- 

 tion through 10,000 

 ohms. 



Observed current 

 in amperes. 



Current calculated 

 from the formula 

 •056376 xd Vd. 





25 



•0004908 



207 



ji 



1,000 



5,121 



6,121 



1267 



7*047 



7-047 



S • 



08 u 



20 



•0003141 



150 





1,000 



5,121 



6,121 



918 



5-106 



5-042 



rj CD 

 S ^ 



16 



•0002010 



115 



6 



10,000 



51,210 



61,210 



704 



3-916 



3-608 



$ « 



14 



•0001539 



110 







10,000 



51,210 



61,210 



673 



3-743 



2-953 



8 



•0000502 



37 







10,000 



51,210 



61,210 



226 



1-257 



1-276 



Constant deflection from standard Daniell cell = 12,252'. 



Description of wire. 



Gauge of wire in 

 mils. 



Area per square 

 inch. 



Deflection. 



Shunt. 



Resistance in coils. 



Resistance of shunted 

 galvanometer. 



Total resistance. 



Equivalent deflec- 

 tion through 10,000 

 ohms. 



Observed current 

 in amperes. 



Current calculated 

 from the formula 

 •057465 x dVd. 





38 



•001134 



121 



9"V 



1000 + 488 



512 



2000 



2420 



13 -461 



13 -461 



i 



20 



•0003141 



123 



)) 



488 



512 



1000 



1230 



6-841 



5-140 



18 



•0002544 



104 



55 



488 



512 



1000 



1040 



5-785 



4-389 



a 



14 



•0001539 



142 



53 



88 



512 



600 



852 



4-739 



3-010 



1 



11 



•0000950 



100 





88 



512 



600 



600 



3-337 



2 '097 





8 



•0000502 



76 



33 



88 



512 



600 



456 



2-536 



1 -300 



The results are plotted out in fig. 3. It will be seen that the 

 observed and calculated results agree to a considerable degree of 

 accuracy except in the case of platinum, which behaves as in the 

 previous experiments, and is generally found to be irregular in its 

 quality. 



These experiments were made upon wires exposed to the air, where 

 radiation is free. I am anxious to repeat them upon wires covered 

 in insulating material and buried in the ground, but I have not been 

 able to do so up to the present moment. The law with reference to 

 such wires has a very important bearing on the size of electric light 



