Rev. Mr Eisdale's Observations on Ground-ice. 169 



able thickness, far beyond any thing that could be effected by 

 the natural operation of the frost in surface freezings. I be- 

 lieve it has seldom occurred to any observer to inquire how these 

 masses of amorphous ice were formed : they all come down the 

 river from a great distance ; and being stopped, at last, by the 

 flow of the tide, and closely compacted together, they are ag- 

 glutinated by the frost, and present great obstacles to naviga- * 

 lion. Now these masses are precisely the ice in question : they 

 are formed in the most rugged currents, adhering to the pro- 

 jecting rocks and rough inequalities at the bottom, and increas- 

 ing upwards, till their bulk and smaller specific gravity, as 

 compared with water, enable the stream to tear them from their 

 fastenings, and hurry them down the river. 



I shall mention a few of the facts which M. Arasro has cd- 

 lected on this subject ; and it is curious enough to observe from 

 his statement, that, what is perfectly well known to every pea- 

 sant, is still called in question by the majority of the natural 

 philosophers of France: they deny the existence of groimd-ice. 

 M. Beaun, in 1788, wrote several dissertations chiefly to esta- 

 blish the existence of ground-ice^ from observations made by 

 himself and by the fishermen on the Elbe. He informs us, that 

 the latter declared that the baskets which they let down into the 

 river, for the purpose of catching eels, were often, when brought 

 to the surface, incrusted with ice ; that the anchors used for 

 mooring their boats, when lost during the summer, again ap- 

 peared in the following winter, being raised by the ascending 

 force of the ice at the bottom, with which they had been cover- 

 ed to such an extent as to render them buoyant ; and that this 

 ground-ice often raised up the large stones to which the buoys 

 were fastened by chains, and caused the greatest inconvenience 

 by displacing these useful signals. 



Desmarest, a member of the French Academy of Sciences, 

 was among the first who made observations on the formation of 

 ground-ice ; but he advances no theory on the subject. He 

 says he had seen flakes of this ice formed at the bottom of run- 

 ning streams, increasing to the thickness of five or six inches in 

 a single night. A more extraordinary fact than this was com- 

 municated to myself about two years ago, when my first paper 

 was announced in the newspapers. A miller, in the western 



