434 Mr. J. T. Bottomley. [June 16, 



Table I. — Carbon D. 



D. 



DD. 



DDD. 



Candles. 



Volts. 



Amp. 



Eesist. 



Volts. 



Amp. 



Resist. 



Volts. 



Amp. 



Resist. 



4 



46-5 



1-02 



45 -6 



373 



1 



37*3 



34 



1-28 



26-6 



10 



52-5 



1-20 



43-8 



42 



1-13 



37-17 



38-5 



1-52 



25-3 



20 



58-3 



1-40 



41'6 



47-8 



1-32 



36-29 



43 



1-77 



24-3 



40 



65 



1-62 



40-1 



52-5 



1-53 



34-3 



48 



2-06 



23-3 



50 



68 



1-70 



40'0 



54-2 



1-60 



33-9 



50 



2 12 



23-6* 









Tab] 



ell.- 



-Carbon C. 









C. 



CC. 



CCC. 



Candles. 



Volts. 



Amp. 



Resist. 



Volts. 



Amp. 



Resist. 



Volts. 



Amp. 



Resist. 



4 



45 



0-86 



52 '33 



34 



0-95 



35-79 



39 



1-16 



33-62 



10 



56 



1-12 



49-99 



39 



1-12 



34-82 



44-5 



1-38 



32 -24 



20 



1 



62 



1-28 



48-43 



44 



1-28 



34-37 



49-5 



1-53 



32-37* 



Now if we suppose the resistance of the carbon filament to depend 

 on the temperature, the resistance diminishing as the temperature 

 increases (though very probably not in simple proportion) ; and if (as 

 we should do in the case of a metallic wire) we use these resistances 

 in order to compare the temperatures of the filaments at different 

 candle-powers, we are led to a remarkable result. Taking the fila- 

 ment D and dividing the resistances of D, DD, and DDD at four 

 caudles by those at the higher candle-powers, we obtain numbers, 

 which may be looked on as ratios of conductances, and which may be 

 taken as indicating, though not exactly representing, corresponding 

 changes in the temperature of the carbon. 



Table III. 



To pass from — 

 4 candles to 10 candles { ™^T' } ^ 1 10 

 4 „ 20 „ 

 4 „ 40 „ 

 4 „ 50 „ 



D. 



DD. 



DDD. 



1-041 



1-096 

 1137 

 1-14 



1-006 



1-028 

 1-087 

 1-100 



1 -047 



1-095 

 1-137 



* The two results which appear last in these tables seem anomalous, and therefore 

 I have not used them in my calculations. 



