Manchester Memoirs, Vol. xliii. (1899), No. 8. 



VIII. Some Preliminary Experiments on the Effect 

 of Pressure on Thermal Conductivity. 



By Charles H. Lees, D.Sc. 



Received and read February 21st, iSgg. 



Recent attempts which have been made to re-calculate 

 the age of the earth from the present rate of increase of 

 temperature downwards — the method used by Lord 

 Kelvin — have directed attention to the very small amount 

 of information we possess as to the effect of increase of 

 temperature and pressure as we proceed downwards, on the 

 thermal conductivity of a given substance. A short time 

 ago some information on the temperature effect was 

 published, and the present experiments are an attempt to 

 furnish information on the other point. They were 

 carried out with a simple apparatus consisting of three 

 horizontal circular steel discs 7*9 cms. diameter, between 

 which two similar discs of the substance to be tested 

 were placed. The centre steel disc 2 2 cms. thick had a 

 flat insulated spiral coil of platinoid wire embedded in it 

 with its plane parallel to the flat surfaces of the disc and 

 midway between them. The two ends of the coil pro- 

 jected from the disc and could be connected through an 

 ammeter and a regulating resistance to a number of storage 

 cells. The upper and lower steel discs I'l cms. thick, 

 formed respectively the bottom and top of two vessels 

 through which a constant stream of tap water could be 

 maintained. The thickness of each disc to be tested was 

 chosen so that approximately the same amount of heat 

 would flow through the various specimens under the same 



June 6th, i8gg. 



