244 Mr R. Adie on Ground-ice. 



poses, viz., that particles of hoar-frost, or frozen dew, falling into an 

 ice-cold stream,- get agglutinated to rocks or obstacles in the bed of 

 it ; and thus form a nucleus for that strange accumulation called 

 ground-ice, which is found nowhere but in running streams. 



Mr Esdaile's explanation stops short after forming a nucleus for 

 the ground-ice, withont informing us whether there is any actual 

 growth of ice under the surface of the water. Now, if ice is sup- 

 posed to grow through the freezing of water about the obtained 

 nucleus, then it would be the laws which produce this increase that 

 would demonstrate the theorj of the formation of ground-ice. But 

 as I believe that evidence can be found to shew that in this climate 

 there is no formation of ice under running water, and that if ice was 

 so formed, it would be clear and hard ; while the vast accumulations 

 of soft ground-ice which are sometimes met with, are no other than 

 particles of ice mixed up with ice-cold water, and submerged, in the 

 same way that earth and sand are suspended during floods in the 

 whole of the water of a river. The only difference is, that the su- 

 perior power of adhesion among minute particles of wet ice, enables 

 them to assume a position of repose for the time being, which is un- 

 natural, or an inversion of hydrostatic laws, while the repose of the 

 earthy particles is in obedience to those laws ; and further, that a 

 large portion of the materials of the so-called ground-ice is formed 

 at thr edges of streams, from whence, in favourable localities, it drops 

 into tiie water and is carried down. 



M) friend Mr James Elliot junior, Hawick, has from time to time 

 been in the habit of sending me descriptions of ground-ice in the 

 river Teviot. In 1841, on 17th November, he writes he saw it in 

 abundance, and that itgwas rare to find it so early. His descriptions 

 confirm in a singular manner Mr Knight's observations as to millions 

 of floating spicules ; also as to their accumulating most on the sides 

 of stones opposed to the current. Mr Elliot has often noticed that 

 where the bed is covered with slimy matter, chiefly composed of the 

 confervoidese, there the ground-ice is in far the largest quantities ; 

 and in a few cases he found it beneath a surface ice covering. In 

 the course of this correspondence we had often discussions as to the 

 relative merits of the difterent theories off'ered for the explanation 

 of the phenomenon ; where Mr Elliot certainly took the lead in re- 

 jecting the received views,* when his own observations and remarks 

 had gone far to give probability to an entangling hypothesis meeting 

 all the facts of the case. I had often occasion to urge the examina- 

 tion of this theory, from a firm conviction that it would end in being 

 established, although I was at the time unacquainted with Mr Knight 

 or Mr Esdaile's writings. Since then I have had opportunities of 

 making some observations, an account of which I now beg to offer. 



In January 1843, I examined some ice formations on the Pent- 



* It is to M. Arago and Dr Farquharsou's modes of accounting for ground- 

 ice that allusion is here made. 



