Intelligence and Miscellaneous Articles. 239 



mission. The water is believed to be afforded by the melting of 

 the upper surface of the glacier under the influence of the heat of 

 summer. This water runs over the surface of the ice, descends 

 into the crevasses, and, if it be admitted that the ice contains 

 capillary fissures (a point which is discussed later), much of it would 

 be absorbed by the mass of the glacier and used in increasing the 

 size of the crystalline grains ; the rest of the water flows off in the 

 subglacial torrent. The low temperature needed for the solidifi- 

 cation of the absorbed water is believed to be due to the continued 

 loss of heat during the winter, the glacier as a whole being a mass 

 the temperature of which can never be above zero, but may fall 

 considerably below. The question as to the mean temperature of 

 the ice at different seasons of the year is discussed at length ; and 

 the author concludes, for a variety of reasons which cannot be 

 quoted here, that the middle of the mass of the glacier has probably 

 a temperature at the end of the winter several degrees below 0° C. 

 This excess of cold would be partially expended in causing the soli- 

 dification of the water which, as already stated, is absorbed into 

 its mass and thus goes to increase its volume. The crystalline grains 

 are therefore to be conceived as growing by accretion, successive 

 layers being added to them at the expense of the water derived from 

 surface-melting, and in the process of the warming of the glacier 

 which goes on during the summer. 



Assuming the correctness of the results of Hugi as to the increase 

 in size of the crystalline grains — that is, in brief, that they increase 

 from a diameter of 1 to one of Icentim., — taking 100 years for the 

 time of their development, the author finds that the annual increase 

 in volume is 4| per cent. Assuming, further, that the cold of 

 winter is all employed in bringing about this increase, it is calculated 

 that the hypothesis advanced is satisfied if the temperature of the 

 glacier descends in winter to — 6"-8 C, or in round numbers — 7° C. 

 This temperature, the correctness of which is obviously dependent 

 upon the accuracy of the assumed data as to the rate of increase of 

 volume, is too low to be accepted, and leads to the inference that a 

 part of the increase is accomplished by a process different from 

 that which has been described. Thus at the end of the summer a 

 considerable portion of the glacier must be at the temperature of 

 melting ice, and in the capillary fissures between the crystalline 

 grains there must be water ; now, as the glacier cools down in the 

 autumn, the first effect of the loss of heat would be the sohdification 

 of this water, and the consequent increase in size of the crystalline 

 grains. Taking into account this last point, the author considers 

 that the temperature that would have to be assumed for the glacier 

 at the end of the winter would be quite within the range of pos- 

 sibility. 



The hypothesis which has been advanced depends upon the as- 

 sumption that the water can find its way into the interior of the 

 glacial mass through the capillary fissures separating the individual 

 grains. This point is one which is yet somewhat doubtful; and 

 the author, after considering the various observations of Agassiz 

 and others, which tell for and against the possibility of such a 



