ACCOUNT OF A CURIOUS PHENOMENON, 209 



in fluids. The water at the bottoms of all deep lakes is con-condufting pro- 

 ftantly at the fame temperature, (that of 41** Fahrenheit,) P^^^^^^"^'^^- 

 fummer and winter, without any fentible variation. This 

 fa6t alone appears to me to be quite fufficient to prove, that if 

 there be any immediate communication of heat betvi^een neigh- 

 bouring particles or molecules of water, de procht en proche, or 

 from one of them to the other, that comnfHiinication mufl be fo 

 extremely flow^, that we m^y with fafety confider it as having 

 noexiftence; and it is with this limitation that I beg to be 

 underftood, when I fpeak of fluids as being non-condu6lors of 

 heat. 



In treating of the propagation of heat in fl uids, I have hitherto 

 confined myfelf to the inveftigation of the (iraple matter of fa6t, 

 without venturing to offer any conjectures relative to the caufes 

 of the phenomena obferved. But the refults of recent experi- 

 ments on the calorific and frigorific radiations of hot and of cold 

 bodies, (an account of which I ftiall have the honour of laying 

 before the Royal Society in a (liort time,) have given me fome 

 new light refpedling the nature of heat, and the mode of its com- - 

 muhication; and I have hopes of being able to (how why all 

 changes of temperature, in tranfparent liquids, muft necelTarily 

 take place at their furfaces. 



I have feen with real pleafure, that feveral ingenious gen- Notice of expe- 

 ileraen, in London, and in Edinburgh, have undertaken the "^^"^l^sajnft 

 inveftigation of the phenomena of the propagation of heat in 

 fluids ; and that they have made a number of new and inge- 

 nious experiments, with a view to the farther elucidation of that 

 moft interelling fubjed. If I have hitherto abftained from 

 taking public notice of their obfervations on the opinion I have 

 advanced on that fubjed, in my different publications, it was 

 not from any want of refped for thofe gentlemen that I re- * 

 mained filent, butbecaufe I ftill found it to be quite irapoffible 

 to explain the refults of my own experiments, on any other 

 principles than thofe which, on the moft mature and difpaf- 

 fionate deliberation, I had been induced to adopt; and becaufe 

 my own experiments appeared to me to be quite as conclufive 

 (to fay no more of them) as thofe which were oppofed to them ; 

 and, laftly, becaufe I confiJered the principal point in difpute, 

 relative to the paffage of heat in fluids, as being fo clearly 

 eftabliftied by the circumftances attending feveral great opera- ' 



tions of nature, that this evidence did not appear lo me to be m 



Vol. IX. — November, 1804-. P dang^ 



