364 



DR. J. A. MARKER ON THE HIGH-TEMPERATURE STANDARDS 



Furnace temperature. 



500 

 600 

 700 

 800 

 900 

 1000 



Corrections to gas thermometer 



reading for compensated furnace 



experiments. 



+ 1-7 

 + 1-5 

 + 1-3 

 + 1-1 

 + -8 

 + -0 



From this table the numbers in the column headed " furnace correction" in 

 Series II. and III. have been deduced by interpolation. For the uncompensated 

 furnace used in the earlier experiments the correction is uncertain to about 0'5 C., 

 and the results are, therefore, only given to this accuracy in the final column 

 representing the " corrected gas thermometer temperature." 



XIX. Method of Calculation. 



The observations taken with the gas thermometer were calculated according to the 

 usual formula. 



Let H = pressure at 0, 

 H= T, 



and let t l and t\ be temperatures of "dead space" with bulb at and at 

 temperature T. 



Let ' = relation of the volume of the whole " dead space " to the volume of the 



bulb at 0, 

 = coefficient of expansion of the gas at constant volume between and 



100, 



3/3 = the mean cubical coefficient of expansion of the porcelain bulb between 

 and T ; 



then 



H n 



therefore T = 



H 



v 



For a given filling H ( 1 + /I- - - ) is a constant if the zero-point remains 



V 1 + a.t l l 



constant. 



The values of a obtained from the steam-point determinations were calculated from 

 the same formula, inserting the value of T obtained from the Regnault-Broch table 

 for the boiling-point of water under the prevailing pressure, as given in the example. 



