METEOROLOGY. 



ON THE DISAPPEARANCE OF ICE 



BY R. H. GARDINER. 



Gardiner, Me., September 30, 1859. 



At the recent meeting of the Scientific Association at Springfield, 

 Colonel Totteu suggested an explanation of the sudden disappearance 

 of the ice on Lake Champlain in the spring of the year. I am induced 

 to state some facts which may throw light on the subject, and explain 

 the reason why ice disappears in such a sudden manner from our ponds 

 and lakes, when it does not do so from our rivers. 



The snow in this vicinity accumulates during the winter ; till towards 

 its close, it is usually from three to four feet in depth. The ice, with 

 the weight of this snow, sinks below the surface; and the water, rising 

 by capillary attraction, wets the snow, which is then frozen into a mass 

 of white ice. Ice formed thus, or by the drippings of a pump, or by 

 water flowing slowly over a frozen surface, is called white ice, and is 

 always opaque. Black ice, on the contrary, is always translucent, and 

 almost transparent, and is regularly crystallized. These two kinds of 

 ice are dissolved very differently. The mean opening of Kennebec 

 river, for the last seventy-five years, is the 6th of April. Before this 

 date, the strength of the current of the river has worn away the black 

 ice beneath, and the white ice is broken up and carried down in masses, 

 continually growing smaller by attrition. The ice on our ponds and 

 lakes, where there is no current, remains nearly a month later, during 

 which time the superficial white ice is melted by the warmth of the 

 weather, leaving the black ice exposed ; and the first hot sun, piercing 

 through the ice, disintegrates it, throwing it into long acicular crystals, 

 which may be sometimes seen heaped upon the shore for two or three 

 days before they entirely disappear. In the year 1842 the ice disap- 

 peared from Kennebec river in a similar manner, a circumstance of 

 very rare occurrence. There had been but little snow during the 

 winter, and no sleighing after the 21st of January. There was, there- 

 fore, but very little white ice formed on the channel of the river. On 

 the 19th of March, in that year, the thermometer rose to 60° of Fahren- 

 heit, and on the 20th, to 52°. The hot sun of those two days pene- 

 trated the exposed black ice, resolved it into crystals, and the white ice 

 from the flats above floated down with the current. So, if two blocks 

 of ice, one black and the other white, be taken from the water and 

 exposed to a hot sun, the former will in a short time be disintegrated 

 and fall into crystals ; while the latter will remain solid, only being 

 diminished in size by the melting of its surfaces. 

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