[barnesI anchor-ice FORMATION 83 



or the surface of a river. This question can no longer be doubted. 

 The theory is far from being so far advanced. I have pointed out 

 the chasms which it still exhibits. If the recital of these cases can in 

 any way contribute towards their being speedily filled up, I shall be 

 amply recompensed for my troublje. 



/ 



Obseev7\tions on Ground-Ice. 



By the Eev. Mr. Eisdale. 



(Read before the Philosophical Society at Perth, on the 28th December, 



1831, and published in the Edinburgh New Philosophical Journal, 



Vol. 17. p. 167. (1834.) 



On the 28th of December, 1831, I read a paper at the meeting 

 of this Society, directing the attention of the members to a particular 

 kind of ice, which seems to be formed in direct opposition to the ordin- 

 ary laws of congelation. The ice to which I allude commences at the 

 bottom of the water, and extends upwards to the surface, and it is 

 produced only in the most rapid and most rugged streams. This 

 is exactly the reverse of the usual process of congelation, which takes 

 place in stagnant water, commencing at the sides of the river or pond, 

 and gradually extending over the surface; when it thickens downwards 

 towards the bottom, and if the frost is sufficiently intense, converts 

 the whole water into a solid mass of ice. The phenomenon did not 

 seem to have attracted any attention in this quarter; and the facts 

 which I stated, and the speculations which I advanced, seemed to 

 excite some surprise: the ice in question, however, is perfectly familiar 

 to every person in the country^ though I never had seen any attempt 

 to account for its formation, and had long puzzled myself in vain to 

 form any plausible theory on the subject. I was not ashamed to 

 confess this at the time, and I expressly declared that the theory which 

 I proposed was intended to elicit, rather than impart, information, and 

 especially to direct attention to the alleged facts which had been com- 

 municated to me, and on which I founded my explanation of the process. 



This kind of ice is well known in all northern climates, from its 

 annoAdng effects in obstructing all works which are carried on by the 

 impelling power of water. When ice collects on the surface of mill- 

 leads it is easily managed; it needs only to be broken and floated 

 down the stream; but when the ice of which I am speaking forms, 

 the case is perfectly hopeless; the leads are gorged up from the very 

 bottom, and it is in vain to attempt to remove the obstruction. This 

 kind of ice is called in Germany grund eis; in France it is known 



