[BARNES] ANCHOR-ICE FORMATION 73 



were, in consequence of the daily and tolerably equal under-additions, 

 believed to form, in this manner, islands of ice, which appeared above 

 the running water." 



No one has hitherto corroborated this mode of increase of ice under 

 water. It is to be regretted that Desraarest did not explain the 

 nature of the observation which induced him to come to such a singular 

 result. Had he, for example, deposited on the flakes of the ice at 

 the bottom objects which always remained visible, while, in rising, 

 all the twenty-four hours, the flakes actually approached the surface 

 of the water, it certainly would have been worth while giving an 

 explanation. 



When, in consequence of a cloudy sky, the atmospherical tem- 

 perature experiences little variation throughout the day and night, 

 the ice at the bottom of the water, according to Desmarest, uniformly 

 increases every twenty-four hours. On the contrary, when the sun 

 shews itself, the ice does not increase during the day. The different 

 layers which are produced during the night after an interval of five 

 or six hours of repose, form distinct beds, which are easily disunited. 

 The current then detaches each layer of ice from the lower one, to 

 which it adheres but feebly, and the river begins to carry it along. 



M. Beaun, a bailiff at Weld Wilhelmsbourg, on the Elbe, pub- 

 lished many dissertations in 1788, in which the existence of ice on 

 the bottom of a river is established, either by his own observations or 

 the unanimous declarations of fishermen, procured after a most anxious 

 investigation. 



The fishermen asserted that, during the cold days in autumn, long 

 before the appearance of ice on the surface of the river, the nets 

 which were at the bottom of the water were covered with such a 

 quantity of grundeis that they drew them up with great difficulty; 

 that the baskets which were used for catching eels also often on being 

 brought to the surface were encrusted with ice; that anchors which 

 had been lost during the summer again appeared in the following 

 winter, being raised up by the ascending force of the ice at the bottom 

 which had covered them; that this ice raised up the large stones to 

 which the buoys were attached by chains, and occasioned the greatest 

 inconvenience by displacing these useful signals, etc., etc. 



These various observations were confirmed by Beaun on his own 

 authority. He says that he discovered, by means of experiment, that 

 hemp, wool, hair, the boiled hair of horses, moss in particular and 

 the bark of trees, are bodies, which, on being placed at the bottom of 

 water, are very speedily covered with ice. He declares that various 

 metals do not possess this property in the same degree. According to 

 him, tin occupies the first rank, — iron the last. 



