Wellington Philosophical Society. 477 



that no one can believe that this great glacier stopped on the banks of the 

 Rhine. 



I do not deny that sheets of ice 3000 or 5000 feet thick exist. I shall 

 maintain, however, as an established fact, that ice if at the temperature of 

 32° Fahr. throughout cannot support a column of its own substance 3000 feet 

 high. Nevertheless, a 3000 feet sheet may exist, although the temperature at 

 the surface of the ice is only 32° Fahr., but in this case the temperature at 

 the base cannot be higher than 13° Fahr. I will explain myself. The specific 

 heat of water is far greater than ice. One pound of ice at 32° Fahr. mixed 

 with one pound of boiling water gives two pounds of water at 51°; so that 

 seventy-one degrees of heat have been lost in the mere conversion of ice into 

 water. We thus see that every pound of ice converted by pressure into 

 water demands a large supply of caloric, as a necessity of its change of 

 condition, and absorbs it instantly from the ice in contact with it above. The 

 ice in the immediate vicinity of the layer of water, hardened by loss of caloric, 

 stops for the moment the further conversion of ice into water. But this state 

 of matters continues only momentarily, the ice below, in its turn, robs the ice 

 above of caloric, and this softened is unable any longer to bear the pressure, 

 and flows away as water j and so the process extends, until a regular gradation 

 of temperature is progressively but uninterruptedly established throughout the 

 mass, and an equilibrium formed between the forces by which the sheet of ice 

 maintains a fixed altitude. That is, we shall have a gradual fall of tempera- 

 ture from 32° on the surface to 13° at the base, the latter degree being the 

 temperature at which ice will sustain a column of 3000 feet. I further 

 maintain that no such column as 3000 feet can continue at that height for an 

 indefinite time, unless the temperature of the air is much lower than 32° 

 because the temperature, if higher than 13°, would gradually creep down to 

 the base of the column of ice, where the lowest stratum would continually 

 melt away in the form of running water. 



And we thus see, as a necessity of the case, that all thick glaciers have 

 running streams at their foot. 



I have brought this under your notice this evening, because no satisfactory 

 explanation has hitherto been given of the cause of running water at the foot 

 of glaciers, nor how it is that sheets of ice 3000 or 5000 feet thick are enabled 

 temporarily to maintain their thickness. 



Dr. Haast, Mr. Travers, and Captain Hutton have given much interest 

 to the subject. The origin and formation of the Canterbury plains have led to 

 the discussion. 



Captain Hutton has come to the conclusion that the formation of the 



Canterbury plains is due to the action of the sea. His argument is, that the 



.plains rise gradually from the sea board with a gentle slope— that in places 



