1882.] On a Deep Sea Electrical Thermometer. 89 



The value of R in terms of the ohm was found to be 



160-520 j 



the temperature being 12°, the values in the above table have been 

 reduced to this temperature. 



From this we find as the value of the ohm — 



Series A -98633 earth quadrant 4 ^ 

 second 



„ B -98558 „ ,2 „ 



„ C -98C76 „ ,3 „ 



while the mean of the whole set is 



1 ohm= -986307 earth quadrant 

 second 



this being determined from nine sets of observations. If we include 

 Part I, giving to each observation only half the weight of one of 

 those in Part II (reasons for this are given at full in the paper), we 

 have finally 



1 ohm=-986271 earth quadrant 

 second 



The value obtained by Lord Rayleigh in his latest experiments with 

 the rotating coil is 



'98651 ear ^ °i ua( lrant 

 second 



The experiments have been made at the Cavendish Laboratory, and 

 our thanks are due to Lord Rayleigh for much kind help and many 

 valuable suggestions. 



IV. " On a Deep Sea Electrical Thermometer." By C. William 

 Siemens, D.C.L., F.R.S. Keceived June 7, 1882. 



In the Bakerian Lecture for 1871, which I had the honour of 

 delivering before the Royal Society,* I showed that the principle of 

 the variation of the electrical resistance of a conductor with its tem- 

 perature might be applied to the construction of a thermometer, 

 which would be of use in cases where a mercurial thermometer is not 

 available. 



The instrument I described has since been largely used as a pyro- 

 meter for determining the temperatures of hot blasts and smelting 



* " Proc. Eoy. Soc," vol. 19, p. 443. 



