473 



It will he seen that the change of level between March 24, 1902, and February 15, 1904, the time 

 during which the observations were in progress, was small. The observer writes: "On the whole, the 

 snow appears to have risen, but this is hardly the general result, for the rise was a ridge, the footpath, 

 between the successive stakes." One must conclude from this that the locality was more windswept, on 

 the average, than the surrounding district, for tho continual use of a definite track in soft material leads 

 to a sinking, and not a rising, of the track, and the only way to account for the " ridge " is to suppose 

 that the freshly fallen, or drifted, snow was consolidated by the feet of those passing over it and, in 

 consequence, was less liable to be blown off. The evidence tends to show that the amount of precipitation 

 during the year was small, for if many heavy falls had occurred they could hardly have failed to have 

 considerably altered the level at the stakes from day to day, and no such alteration seemed to have 

 occurred. 



It may also be noted that practically no thawing of the snow occurs, except here and there where the 

 sun shines on a neighbouring exposed surface of rock, and, in general, the summer temperature is so low 

 that the only appreciable loss is by evaporation. 



The evaporation experiments give very interesting results. Shallow dishes were filled with water, which 

 was allowed to freeze, and then the dish and ice were weighed day by day and the difference between two 

 consecutive weights gave the loss by evaporation. Three dishes were used, two giving an area of 

 12 sq. inches (3 in. by 4 in.), and the third an area of 24 sq. inches. This latter was blown away before it 

 had been very long in use and was not reinstated. As might bo anticipated, the loss of weight from the 

 two similar dishes was not invariably the same, but, on the whole, the agreement was very fair. The 

 evaporation from the third and larger dish was less than double that from the smaller, this being in 

 accordance with the result found in England when the evaporation from small surfaces of water of different 

 areas is observed. 



The observations were discontinued in the summer, because when any of the ice was melted it was 

 difficult to avoid losing some of the water before or during the weighing. 



The following table is formed from the mean of the two 4-in. by 3-in. dishes. In some cases one only 

 was available, and in such cases the one was used. The figures do not give strictly the evaporation for 

 the month, partly because here and there a day's record is missing, partly because the observations were 

 taken once each day, generally between Noon and 4 p.m., and thus the record for June, say, omits 

 12 or 14 hours at the beginning of June and includes a similar period in July. 



Occasionally a small increase of weight was noted. These increases have uot been subtracted from 

 the total. 



The losses given in the observer's book are in grammes; these have been put into losses of thickness, 

 expressed in inches by using the factor 0'051. 



TABLE II. Monthly Evaporation. 



3 P 



