1^ On the Ground-Ice observed in 



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 o{ 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 th6 following winter, being raised up by the ascend- 

 ing 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, &c. &c. 



These various observations were confirmed by Beaun on his 

 own authority. He says that he discovered, by means of expe- 

 riment, 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 co- 

 vered 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. 



Mr Knight, the celebrated botanist, has related an observation 

 in the 106th volume of the Philosophical Transactions, which is 

 the more valuable, as it seems in some respects to afford a clue 

 to the secret of the formation of ice on the bottom of rivers. 



" In a morning which succeeded an intensely cold night, the 

 stones in the rocky bed of the river appeared to be covered with 

 frozen matter, which reflected a kind of silvery whiteness, and 

 which, upon examination, I found to consist of numerous frozen 

 spicula crossing each other in every direction, as in snow, but 

 not having anywhere except very near the shore assumed the 

 state of firm compact ice. The river was not at this time frozen 

 over in any part ; but the temperature of the water was obvi- 

 ously at the freezing point, for small pieces of ice had every- 

 where formed upon it in its more stagnant parts near the shores ; 

 and upon a mill-pond, just above the shallow streams (in the 

 bottom of which I had observed the ice), I noticed millions of 

 little frozen spicula floating upon the water. At the end of this 

 mill-pond the water fell over a low weir and entered a narrow 



