[baknes] anchor-ice FORMATION 85 



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 

 fiakes of ice formed at the bottom of running streams, increasing to 

 the thickness of five or six inches in a single night. A more extra- 

 ordinary fact than this was communicated to myself about two years 

 ago, when my first paper was announced in the newspapers. A miller, 

 in the western part of the country, wrote me a letter containing a 

 theory of his own, ascribing the phenomenon to the prevalence of par- 

 ticular winds; in confirmation of which he mentioned, that during a 

 severe frost, when his mill-lead was entirely free of any kind of ice, 

 he had occasion one day to lop some branches from a tree which over- 

 liung the lead; one of them fell into the water and was left there, 

 as he did not apprehend any consequences from such a trifling occur- 

 rence. Next day, however, to his astonishment, the water was turned 

 entirely out of the lead, and had overflowed a large portion of an 

 adjoining meadow. On proceeding to ascertain the cause, he found 

 that a solid barrier of ice had l)een formed across the lead where the 

 branch had fallen in, so as completely to prevent any water from pass- 

 ing, whilst the rest of the lead was free from ice. He ascribes this 

 to the prevalence of a very sharp northeast wind which had blown 

 during the night.. There can be no doubt that this is converting into 

 a cause, what is merely an accidental concomitant, as I shall shew 

 hereafter. 



On the 16th February, 1827, M. Hiigi, president of the Society 

 of ISTatural History at Soleure, while standing on the bridge of the 

 Aar, and when the river was perfectly clear of ice, observed in these 

 circumstances, large icy tables continually rising from the bottom of 

 the river, in a vertical direction, and with such buoyancy, as to rise 

 considerably above the surface, when they immediately sunk into a 

 horizontal position, and floated down the stream. A great manv facts 

 of the same kind may be found in M. Arago's paper, which is given 

 in the Edinburgh New PhUosopliical, Journal for July last; which is 

 the first paper on the subject of ground-ice that I have ever seen. 



Let us now attend for a little to the cause of these singular phen- 

 omena, and I will be bold to say that no adequate cause has yet l^een 

 assigned for them; unless the hints which I formerly threw out on 

 the subject as queries, rather than as ascertained facts, shall be considered 

 sufficient for the purpose. ]\r. Arago gives his theory as to the cause at 

 great length. It is simply this, that the different strata of water, in a 



