128 On the Ground-Ice observed in 



bited any projection, there was a small piece of ice, which might 

 have been supposed, at a distance, to be a reuniting of tufts of 

 cotton. This ice became disengaged from the bottom from time 

 to time, and floated on the surface. It had all the appearance 

 of the /rnind-eis of the German watermen. 



M. Hugi, president of the Societe d^'Histoire Naturelle de 

 Soleure, is the philosopher who, in my opinion, has seeji the phe- 

 nomena of the formation of ice at the bottom of water displayed 

 on the greatest scale. His first observations were made in 

 1827. 



From the 2d to the 3d February of that year, the river 

 Aar, at Soleure, was breaking up the ice ; on the 15th it was com- 

 pletely open. It flowed slowly on the 16th, and the water was 

 perfectly pure. On this day, in consequence of a westerly wind, 

 a multitude of large icy tables were continually rising from the 

 bottom about 60 or 70 feet below the bridge, and over a surface 

 of upwards of 450 square feet. I ought to add, as this cir- 

 cumstance confirms what Hales was told by the fishermen of the 

 Thames, that the great proportion of the flakes of ice mounted 

 vertically, till 5 or 6 decimetres above the surface of the water, 

 and after remaining a few minutes in this position, they sunk 

 down, and floated horizontally. 



After a certain time, the flakes of ice became more scarce ; 

 but they had increased to such an extent, that many, though 

 almost vertically raised above the water, still rested in the 

 bed of the river on one of their sides, and in which position 

 they remained stationary for a long time. The phenomenon 

 lasted for about a couple of hours. 



Below the bridge, the Jar flows with rapidity over an inclined 

 channel of 20 or 30 degrees, and in many places is quite stony. 

 Beyond the place where the flakes of ice arose, the water, al- 

 ready more tranquil, always exhibited a sort of eddy. 



The temperature of the air was — 5°.7 centig. ; near the wa- 

 ter — 4°.9; close to the surface of the river, -f 2°.l. The water 

 near the arches, where there was no ice, was at -f-3°.0 ; at the 

 bottom, where the ice ascended, 0°.0. 



There is one circumstance which lessens the importance of 



