20S AC60CNT OF A CURIOUS PHENOMKNOlf. 



fcended ; and, in confequence of this inclination. Its moutM 



or opening, at the furface of the ice, was not circular, but 



elliptical. 



They are fre- From our guides I learnt, th^t thefe cylindrical holes are fre- 



quen y oun . qjjgj^^|^, found on the level paf ts of the ice j that they are formed 



during the fummer, increafing gradually in depth, as long as 



the hot weather continues; but that they are frozen up, and 



djfappear, on the return of winter. 



Inference againft I would alk thofe who maintain that water is a cOndu(5lor 



the conducing ^f ^g^t, how thefe pits are formed? On a fuppofition that 

 power or water. . . . . , . 



there is no direct communication of heat between neighbour- 

 ing particles of that fluid, which happen to be at different 

 degrees of temperature, the phenomenon may eafily be ex- 

 plained ; but it appears to me to be inexplicable on any other 

 fuppoiition. 



The quiefcent mafs of water, by which the pit remains con- 

 flantly filled, muftneceflarily be at the temperature of freezing; 

 for it is fiirrounded on every lide by ice : but the pit goes on to 

 increafe in depth, during the whole fummer. From whence 

 comes the heat that melts the ice continually at the bottom of 

 the pit? and how does it happen, that this heat a<5ts on the 

 hottom of the pit only, and not on its fides ? 

 Solution of the Thefe curious phenomena may, I think, be explained in the 



efFeft by the following maimer : The warm vvinds which, in fummer, blow 

 greater denfity of ... _ , . , ... . . _ , , 



water above zero, over the iurtaceot this column of ice-cold water, mult undoubt- 

 edly communicate fome fmall degree of heat to thofe particles 

 of the tluid with which this warm air comes into immediate 

 contact ; and the particles of the water at the furface fo heated, 

 being rendered fpeciiically heavier than they were before, by 

 this fmall increafe of temperature, fink flowly to the bottom of 

 the pit ; where they come into contact with the ice> and commu* 

 iiicate to it the heat by which the depth of the pit is continually 

 increafed. 



-"This operation is exadly fimilar to that which took place in 



one of my experiments, (See my Ellay on the Propagation of 



heat in Fluids, Experiment 17,) therefults of which, no perfon, 



to my knowledge, has yet explained. 



Conftanttem- There is another very curious natural phenomenon, which I 



peratare of wa- couid wifli to fee explained in a fatisfadory manner, by thofe 



of deep lakes, who ftill refufe their atfent to the opinions I have been led to 



offered in fup- adopt, refpe6ting the manner in which^ beat is propagated 



port of the non- - 



