180 On the formation of Ice. 



The filling of the ice-hoiises (which, within a few years, 

 have become considerably numerous in this town,) has af- 

 forded good opportunities of observing some small circum- 

 stances, the mention of which may not be superfluous, al- 

 though, perhaps, not entirely novel. 



The first thing to be noticed is the regularity of the lay- 

 ers of ice produced by each night's congelation. In masses 

 fifteen inches thick,* there are twenty-one distinct layers — 

 quite as distinct as those of agate, or striped jasper, or of 

 the annual rings produced by the growth of wood. These 

 layers, near, and at the top, are from one and a half to two 

 inches thick, and at the bottom, next the stream, they are 

 from one-half to one quarter of an inch — giving an average 

 of nearly three-quarters of an inch. Although, (owing 

 doubtless to the different degrees of cold, in different nights,) 

 the layers of ice do not decrease in an uniform ratio ; their 

 decrement is still tolerably regular, and when we compare 

 the extremes (granting that the cold was not diminished, 

 and the truth was it was rather increased on the whole,) we 

 are struck with the wide difference, and, of course, with 

 the almost non-conducting power of ice in relation to heat. 



This is one provision, among others, made by the creator, 

 to prevent very deep congelation, which would be attended 

 with deplorable consequences. Had the accumulation of 

 ice, in the present instance, gone on uniformly, in the high- 

 est ratio, the ice would, during these twenty-one nights have 

 been forty-two inches, or three feet six inches thick, and 

 during eight weeks or fifty-six days of such severe weather, 

 it would have become 112 inches, or nine feet four inches 

 thick, which would insure winter's cold, and consequent 

 sterility, in tbe vicinity of that ice during the next summer; 

 (for the heat would not be sufficient for its fusion,) and con- 

 sequently perpetual cold would be established ; the suc- 

 ceeding winter, and all succeeding winters, would only aug- 

 ment the effects. 



It is now a good while, since Count Rumford pointed out 

 the most important reason which prevents the entire conge- 

 lation of deep waters in winter, — namely, that water cooled 

 to 40° begins to expand, and continues to do so, thus be- 



* Jan. SO. The cakes of ice are now twenty one infiiies thick, but still, 

 although the recent cold has been much the most severe, the lower layers of 

 ice are only from i to ?ths of an inch thick. 



