66 ROYAL SOCIETY OF CANADA 



sometimes in the underside enclosing stones and gravel brought up by 

 them ad imo." 



In February of 1827, M. Hugi, President of the Society of Natural 

 History at Soleure, reports that while standing on the bridge over the 

 Aar, when the river was clear of ice, he observed large ice tables con- 

 tinually rising from the bottom, in a vertical direction and with such 

 buoyancy as to rise considerably above the surface, when they imme- 

 diately sank into a horizontal position and floated down stream. 



This is in almost perfect accord with what takes place in our 

 northern rivers during the da}'time under a bright sun or during mild 

 rainy weather. 



In 1835 the great philosopher, M. Arago, published an interesting 

 paper on the subject in the Annuaire du Bureau des Longitudes. He 

 mentions the following rivers where ground-ice was met with and the 

 date of such observation. In the Thames, by Hales, in 1730; in the 

 river Déonie, France, in 1780; in the Elbe, by Beaun, in 1788: in 

 the Teine, Herefordshire, in 1816; in the Ehine at Strasburg, in 

 1829; and in the Seine, in 1830. 



In the Ed mburgh Pliilosopliical Journal iox 183-1 there is an inter- 

 esting paper on " Observations on Ground Ice," by the Eev. Mr. Eisdale, 

 who attempts to explain the phenomenon on an original theory of his 

 own. He states that the ice commences on the bottom and extends 

 upwards to the surface, and is produced only in the most rapid and 

 most rugged streams. 



The Eev. Dr. Farquharson published two important papers on 

 Ground-gru in the Philosophical Transactions of 1835 and 1841. His 

 observations were made of the ice in the rivers Don and Leochal, in 

 Aberdeenshire. The conclusions he arrived at are that ground-gru 

 is formed by radiation, and he endeavoured to substantiate his reason- 

 ing upon the principle of the formation of dew. 



The first use of the term anchor-ice which I have been able to find 

 is in the Encyclopasdia Americana, published by Carey and Lea of 

 Philadelphia in 1831. Under the article on ice we find the author, 

 after referring to ground-ice, states, that " a kind called anchor-ice 

 appears to be formed at the bottom or at least under the surface of 

 rapid rivers, perhaps owing to the comparatively slow motion of the 

 water at the bottom of a stream." 



The term anchor-ice, applied to ice anchored at the bottom, 

 peems thus to have originated in America. Much confusion exists in 

 regard to the relation of this ice to frazil-ice, brought about partly 

 by a confusion of terms, and partly from the fact that immense quan- 

 tities of frazil-ice become attached to the bottom by freezing to the 



