THE 

 LONDON, EDINBURGH, and DUBLIN 



PHILOSOPHICAL MAGAZINE 



AND 



JOURNAL OF SCIENCE. 



[FIFTH SERIES.] 



JULY 1887. 



I. Conduction of Heat in Liquids. — Historical Treatment* 

 By C. Chkee, M.A., Fellow of King's College, Cambridge*. 



POSSIBLY the earliest experiment of any note on the 

 conduction of heat in liquids is due to Despretzf. He 

 supplied hot water at intervals of five minutes to a metal 

 vessel in contact with the upper surface of water contained in 

 a vertical cylinder, and observed the readings of a series of 

 thermometers at different depths, some in the axis and others 

 at or near the cylindrical surface. He specially observed the 

 temperatures in the stationary condition when the heat sup- 

 plied just balanced that lost by the apparatus. He found that 

 the temperature in the axis of the cylinder then followed 

 precisely the same law as in a metal bar of small cross section 

 heated at one end to a constant temperature ; i. e. if v denote 

 the temperature at depth x, he found v one~ qx , where ^de- 

 pends on the material and dimensions of the cylinder. By 

 comparison of two cylinders of the same material he found 

 \ogq oc (diameter)", a relation which also holds in the case of 

 metal cylinders. Near the surface of the water the tempera- 

 ture did not vary much over a horizontal cross section, but at 

 depths of the same order as the diameter of the cylinder the 

 variation was very considerable. As a single experiment 

 occupied Despretz for sixty hours, and the method seems 



* Communicated by the Author. 



t Comptes Rendus, 1838, p. 933 j and Ann. de Chim. et de Phys. 1839 ; 

 lxxi. p. 216. 



Phil. Mag. S. 5. Vol. 24. No. 146. July 1887. B 



