208 



REPORT — 1897. 



Rowland's thermometers with a platinum thermometer made by Mr. 

 Griffiths. The result of this discussion is to leave Rowland's original 

 value unchanged at 15°, and to raise it by four parts in 4,000 at 25°, 

 making the rate of variation of the specific heat of water almost exactly 

 the same as that given by Griffiths's experiments throughout the same 

 range. 



The following table gives the numerical values : — 



Values of the SiJeciJlc Heat of Water at 15° C. 



1. By mechanical friction : — 



Variation of the Specific Heat of Water. 



Joule's (1878) result is given by Schuster and Gannon {Proc. Roy. Soc, Ivii. 

 p. 31) as 775 foot-pounds at Greenwich per degree Fahr. As Professor Schuster 

 has examined the thermometers employed by Joule, this value is adopted as the most 

 trustworthy statement of the result of Joule's experiments : it is reduced to ergs and 

 the Centigrade scale. 



Miculescu (^Ann. Chim. Phys. [6], xxvii. 237) states his result as 426-84 kilogramme- 

 metres per kilogramme-degree of the normal hydrogen-thermometer between 10° and 

 13°. Taking^ = 980 96, this is equivalent to 4187 X 10 ergs per gramme-degree. The 

 mean temperature ll°-5 hivs been adopted and reduction to 15° has been made by 

 means of the rate of variation given by Rowland's experiments. 



Reynolds' and Moorby's experiments {Proc. Roy. Soc, Ixi.) refer to the whole range 

 from 0° to 100°. Their result is stated, in foot-pounds at Manchester and degrees 

 Fahr., as 776-94. To reduce to ergs and the Centigrade scale this number has 

 been multiplied by 18 x 3048 x 981-34. 



Schuster and Gannon (^Proc. Roy. Soc, Ivii. 25-31). 



Rowland's and Griffiths' results are quoted from Day (Phil. Mag., August 1897, 

 p. 171), whose statement is adopted by Griffiths in Nature for July 15, 1897. 



