1883.] On the Dependence of Radiation on Temperature. 175 



a, /3, 7 of the empirical formula connecting the resistance of the wire 

 with its absolute temperature were determined. The wire was enclosed 

 in a glass tube, stopped at either end with a plug, through which the 

 wire passed centrally. The tube was fixed in a metallic trough, with 

 an aperture in its cover sufficiently large to admit a mercurial thermo- 

 meter placed in contact with the tube. In the first instance, the 

 trough was filled with melting ice, and the resistance of the wire 

 measured by a Wheatstone bridge. The ice was then removed, and 

 two Bunsen burners were placed below the trough, and the tempera- 

 ture gradually raised by increasing the pressure of the gas in the 

 burners. 



In this way a series of simultaneous observations were made of the 

 temperature of the wire and its corresponding resistance up to 100° C. 

 The results are given in the subjoined table. Care was taken at each 

 reading that the thermometer had become stationary, and really 

 represented the temperature of the wire. A second series of observa- 

 tions were taken as the wire cooled from 100° to zero ; and the results 

 are likewise given in the table. 



Temperature rising. 



Temperature falling. 



Tempera- 



Eesistance 





i'r 



Tempera- 



Resistance 





rt 



ture. 



ohms. 







ture. 



ohms. 





r o 



0° C. 



•5847 



1 



•oooo 



100° C. 



•6827 



1 



•1680 







-5837 







97 -7 



•6815 



1 



1660 







•5827 







95-5 



•6798 



1 



1631 







•5827 







90-0 



•6741 



1 



•1533 



66-3 



•6467 



1 



•1064 



78-5 



•6619 



1 



1324 



66 6 



•6469 



1 



•1068 



76-6 



•6601 



1 



•1294 



67-2 



•6477 



1 



•1081 



62-5 



•6463 



1 



•1057 



68 -5 



•6547 



1 



1201 



48-3 



•6308 



1 



•0792 



70-2 



•6557 



1 



•1218 



46-6 



•6299 



1 



•0777 



72-2 



•6567 



1 



1235 



32 -2 



•6147 



1 



•0517 



81-6 



•6597 



1 



•1286 



31 6 



•6140 



1 



•0505 



85-0 



•6657 



1 



•1389 



21 -6 



•6052 



1 



•0354 



86-1 



•6697 



1 



•1458 







•5857 



1 



•oooo 



93 2 



•6727 



1 



•1509 







•5857 







95 



•6747 



1 



•1543 











98-8 



•6777 



1 



•1594 











99 5 



•6817 



1 



•1663 











For the reduction of the 26 equations obtained from these obser- 

 vations, the method of least squares was employed, giving 



«=0 '0119 



/3=0-00112 



7=0-512 



