Rivers during Winter. 127 



channel, where its course was obstructed by points of rock and 

 large stones. By these^ numerous eddies and gyrations were 

 occasioned, which apparently drew the floating spicula under 

 water ; and I found the frozen matter to accumulate much more 

 abundantly upon such parts of the stones as stood opposed to 

 the current, where that was not very rapid below the little falls 

 or very rapid parts of the river. I have reason to believe that 

 it would have accumulated in very large quantities if the wea- 

 ther had continued sufiiciently cold ; for I had been informed 

 on good evidence, that, some years before, the whole bed of the 

 river in the part above mentioned had been covered over with a 

 thick coat of ice. 



" On some large stones near the shore, of which parts were 

 out of the water, and upon pieces of native rock, under similar 

 circumstances, the ice beneath the water had acquired a firmer 

 texture, but appeared from its whiteness to have been first 

 formed of congregated spicula, and to have subsequently frozen 

 into a firm mass, owing to the lower extremity of the stone or 

 rock. Ice of this kind extended in a few places eighteen inches 

 from the shore, and lay three or four inches below the level of 

 the surface of the water, and did not dissolve so rapidly as that 

 which was deposited upon stones more distant from the shores.*" 



On the 11th of February 1816, the engineers of bridges and 

 roads residing at Strasburg, saw above the bridge of Kehl that 

 many parts of the channel of the Rhine were covered with ice. 

 About ten o'clock a. m. this ice became loose, rose to the sur- 

 face, and floated. 



The thermometer in the open air stood at — 12° centigr. The 

 water in the river at every depth was at zero cent. The ice at the 

 bottom was only formed in places, however, where there were 

 stones and angular stuff*. It was spongy, and formed of icy 

 spicula. 



The overseers of the bridge stated that it never appeared on 

 the surface until after 10 or 11 o'clock in the morning. 

 P The canal of Saint- Alban conveys the waters of the Birse 

 through the town of Bale. It is very limpid, and flows with 

 great rapidity. During the winter of 1823, Professor Merian 

 carefully examined the bed of the canal, which, in general, is 

 covered with pebbles, and saw that wherever the bottom exhi- 



