Rivers during Winter, 129 



these observations as to the temperature ; it is not established 

 that the ice at the bottom of the river on the 16th February wa» 

 formed on that day, and these ices might again cover the bed of 

 the river for many days afterwards. 



The second series of the observations of Mr Hugi were made 

 in the month of February 18:29!' 



On the 11th of this month, the Aar near Soleure was quite 

 free from ice. For many days the temperature of the atmo- 

 sphere was from +4° to +6° centigr. During the night of the 

 llth-12th, it suddenly fell to — 14° centigr. On the 12th at 

 sunrise, the river began to exhibit numerous floating pieces 

 of ice. We must by no means omit to add, that the water, 

 either near the banks, or in the shady places where it was per- 

 fectly calm, as yet bore no trace of congelation on its surface. 

 It therefore could not be said that the floating masses were de- 

 tached from the banks. It would have been as unfounded to 

 have supposed that they had proceeded from any large sheet of 

 ice situated farther up the river, as at Altrey, a league and a 

 half above Soleure, the river hardly exhibited any ice. Besides, 

 flakes of ice commenced soon to rise up above the bridge, in the 

 place where they had been seen in 1827. Towards mid-day, 

 islands of ice were seen formintj in the centre of the river. On 

 the 13th February these were 23 in number. The largest was 

 upwards of 200 feet in diameter. They were surrounded with 

 open water, resisted a current which almost ran at the rate of 

 200 feet in a minute, and extended over a space of one-eighth 

 of a league. M. Hugi visited them in a small boat. He landed, 

 examined them in every direction, and discovered that there was 

 a layer of compact ice on their surface of 5 or 10 centimetres in 

 thickness, resting on a mass having the shape of a cone reversed, 

 of a vertical height of 3 or 4 metres, and fixed to the bottom of 

 the bed of the river. These cones consisted of half-melted ice, 

 gelatinous, and very like the spawn of a frog. It was softer at 

 the bottom than at the top, and was easily pierced in all direc- 

 tions with poles. Exposed to the open air, the substance of the 

 cones became quickly granulated like the ice that is formed at 

 the bottom of rivers. 



When these observations were being, made, the temperature 

 of the air, at 9 metres above the Aar, was, — 11°.2 centigr.; at 



VOL. XV. NO. XXIX. — .lULY 1833. I 



