432 



PROCEEDINGS OF THE AMERICAN ACADEMY. 



Table I shows the resistance of this platinum thermometer at the 

 five temperatures previously referred to, and the change per degree of 

 its resistance over the four intervals of temperature. 



TABLE I. 



It will be observed from this table that between 0° C. and 80° C. 

 the change per degree in the resistance of the platinum wire is very 

 nearly constant, and over this range of temperature shows a variation 

 of about 0.7 per cent. Between 80° C. and 100° C. it increases about 

 1.2 per cent. As all the temperatures at which the platinum ther- 

 mometer was used were below 80° C. the temperature of the liquid is 

 obtained with sufficient accuracy from a knowledge of the change in 

 the resistance of the platinum thermometer. 



An attempt was made to fit the data into the formula of Callendar 

 and Griffiths. 2 



T-pt = h 



where 



_Vioo 



looj 



T = absolute temperature, 

 8 = constant, 



(B, - Bo) 100 



pt 



R 



100 



Ba 



Bq = Resistance of thermometer at 



B, = 



c. 



t° C. 

 100° C. 



This attempt was, however, unsuccessful, and it appears that the 

 law given by Callendar and Griffiths does not hold for the specimen of 

 platinum wire here used. 



« Phil. Trans., 182, A. (1892), p. 119. 



