Bev. J. F. Blake — On the Motion of Glaciers. 497 



first be brought to melting point, and then so many nnits of heat must 

 be supplied in addition to melt it. Suppose a melted particle in the 

 midst of ice colder than at melting point, its heat would be distri- 

 buted in raising the temperature of the surrounding ice, according 

 to its conductivity, and what was left would be insufficient to melt 

 any other particle of its own size. Hence, before the solidifying of 

 one particle could be sufficient for melting another, the whole sur- 

 rounding mass must be at melting point, and this, I believe, is not 

 by any means the temperature of the interior of a glacier ; and there 

 must be some cause for the devotion of the spare heat to one particle 

 alone, to say nothing of the cause which is to bring about a perpetual 

 doing and undoing of the same operation. If there could be any 

 such passing on of a melted state through a body to the other end, 

 we ought to see a glass rod held in the fire melting at the end away 

 from the fire, or does the outside particle refuse to melt ? A candle, 

 too, ought to melt in the socket instead of near the lighted wick, 

 and to bulge out into abnormal obesity. 



But what does happen when ice is subjected to heat on one side ? 

 First, the heated side is raised to melting point, while as we recede 

 from that side the temperature gradually diminishes to its lowest 

 point at the side we may suppose most remote from the source of 

 heat. The temperature at any point between these tw;o settles down 

 to a fixed amount according to the temperatures of the two ends, 

 the surrounding temperature of the whole, and the conductivity of 

 the ice, and can only vary with one of these. The only variable 

 elements of the four are the surrounding temperature, and the 

 temperature of the other end, which are obviously connected 

 together. The temperature of the hotter end (being the melting 

 point of ice) and the conductivity may be considered for present 

 purposes invariable. If more heat be now applied, it is spent in 

 keeping up this state of the ice as to temperature against all possible 

 losses and in melting that part of the ice that is nearest to it. No 

 amount of this additional heat will alter the state of the interior — 

 except so far as it may alter the other conditions on which it depends. 

 However, if changes in the other conditions take place, the source 

 of heat may be a long time bringing about this settled state of 

 temperature, and during this time it will of course cause changes in 

 the temperature of the interior. But no amount of external heat 

 could possihly bring about internal melting in a uniform mass of 

 ice. It is simply a myth. These statements of mine will be recog- 

 nized by any physicist as a piece of elementary knowledge obtainable 

 from most text-books on heat, I cannot think of anything that 

 would explode the theory more effectually than these simple well- 

 known facts. 



But now it may be asked — How then does the glacier move ? 

 For it certainly moves particle by particle, for it alters its shape, and 

 heat has some influence on it, because it moves faster in summer 

 than in winter. In reply I may say that I think the true answer to 

 this question must be made by one who has opportunities of making- 

 special observations on glaciers, so as to ascertain, with a view to 



DECADE II. VOL. III. — NO. XI. 32 



