454 



Mr. J. D. Hamilton Dickson on 



the resistance of a certain platinum wire at low temperatures, 

 the wire being at various times immersed in liquid air, cooled 

 paraffin, ether, and a mixture of carbonic acid and alcohol. 

 There were altogether ninety-seven observations. Arranging 

 these, irrespective of their series, in order of temperature, the 

 lowest being — 190°*2 and the highest 0° on the hydrogen 

 thermometer (with Centigrade scale), I adopted Table IV. 

 from which to calculate, by the method of least squares, the 

 formula 



(R + 293-28615) 2 = 119'49237(^h + 976-8586). 



(12) 



Table IV. 



R, in 



obms. 



Temp. 



(H). 



Observed. 



Tempe- 

 rature. 

 Calcu- 

 lated. 



v. 



V 2 . 



Remarks. 



48-37 



00 



00 







•00 



Obs. 97. 



45-22 



- 18-4 



- 17-9 



-•5 



•25 



Avge. of 2 obs. lying within o, 6. 



41-59 



- 38-4 



- 38-4 







•00 



2 „ „ 0°-6. 



38-39 



- 56-1 



- 56-2 



+•1 



•01 



3 „ „ l°-6. 



34-12 



- 78-9 



- 79-8 



+•9 



•81 



8 „ „ l°-0. 



28-87 



-108-5 



- 108-3 



-•2 



•04 



Obs. 77. 



25-14 



-128-2 



-128-3 



+-1 



•01 



„ 56. 



2166 



-1470 



-146-8 



— •2 



•04 



„ 46. 



16-29 



-175-1 



-174-8 



-•3 



•09 



Avge. of 8 obs. lying within o, 6. 



13-34 



-189-9 



-190-0 



+•1 



•01 



8 „ „ 0°-6. 



From this formula the results in the 3rd column of Table IV. 

 were obtained, leading to the divergences in the 4th column, 

 and their squares in the 5th column, whence the probable 

 value of the divergence between a calculated and an observed 

 temperature is found to be 



% 2 

 9 



•6745 



s/- 



= •25, 



or a quarter of a degree over a range of nearly 200°. The 

 hydrogen- temperature of the absolute zero (R=0) given by 

 this formula is —257° 0. 



Messrs. Holborn and Wien give the following formula 

 connecting temperature and resistance " true to about 1°," 



t= -258-3 + 5-0567R + 0-005855 E 2 , 



(13) 



and they add, as examples of the closeness between observed 

 and calculated temperatures, these three results : — 



