RESULTS OF BALMAT’S MEASUREMENTS. 
189 
April. — First week fine ; second week cold with snow ; changeable to the end of 
the month. 16th. Source of Arveiron has not much increased in water since the 
middle of March. In the end of April the snow first disappeared from the lower 
part of both glaciers. 
May. — The first half of the month fine, with occasional snow ; the second half 
changeable, with rain. 17th. The source of the Arveiron has increased three-fourths 
( means probably in the ratio of four to one) since the middle of April, and is dirty. 
The ice-vault is not yet formed. 26th. The Glacier des Bossons advances rapidly 
and is crumbling into pyramids. The end of the glacier is at least eighty-five feet 
high and advances considerably, particularly during the month of May ; and widens 
greatly. 
June. — A changeable and wet month ; a very late season*. The snow did not 
entirely disappear from the Mer de Glace opposite the Montanvert till the beginning 
of July. 6th — 7th. The vault opened at the source of the Arveiron. The quantity 
of water since the end of May is the usual summer supply. 
July. — Commenced with warm weather. 5th. Thermometer 2 7° Reaum. The snow 
has disappeared from the ice opposite Montanvert, but some patches remain on the 
way to the Jardin. The Mer de Glace is much higher in level (about forty feet) 
than in former years, and the marks made in the rock at the Angle (in 1842) are all 
covered. The crevasses much the same as usual. The glacier of Bossons has also 
increased greatly, and appears to be approaching its old moraines. The register for 
the greater part of July has not come to hand. 
August. — A very changeable rainy month. 8th or 9th. The arch at the source of 
the Arveiron fell in, and did not form again during the season. 
September. — Also a changeable month. Rain twelve days. 
October. — A very fine month. No rain mentioned after the 7th. 
A careful examination of this interesting register will explain several of the appa- 
rently irregular inflections of the curves of glacier motion. Thus (to continue out- 
general remarks, p. 186) we find 
V. At the upper station on the Glacier des Bois the least velocity occurred in De- 
cember, whilst at the lower station (and at both of those on the Bossons) a minimum 
coinciding also with that of the temperature of the air took place in January. This 
coincides with the important fact noted in the preceding register, that the upper part 
of the Mer de Glace was covered with snow from the 16th of October, which only lay 
in the valley of Chamouni from the 20th of January ; the snow screening the ice 
from the extremity of the cold. 
VI. The comparative march of the two glaciers bears a remarkable relation to 
their positions and form. In the Bossons we detect at once the sudden transitions 
and seemingly capricious changes of a torrent ; in the Mer de Glace we have the 
* It will be seeD from the temperature curves that the thermometer fell considerably in the latter part of 
June, both at Geneva and St. Bernard. 
