Natural History.. 397 
destruction described. This means had, at the end of the summer of 
1822, reduced the glacier, which originally covered the river for a 
length of 1350 feet, to an extent of 498 feet only. The cold-winter 
of 1822-3 and the following spring, increased the glacier to 924 feet, 
and this new part was excessively rugged and dangerous to work upon, 
and continually exposed to masses falling from the upper glacier. It 
was requisite, however, that this should be first destroyed, which was 
done atthe risk of many serious accidents by currents of water as 
before, during the summer of 1823, and such advantage taken of the 
rest of that cold short summer as to diminish the whole glacier to 252 
feet only. Thus, notwithstanding the accessions which it must have 
teceived during the last winter, there is little doubt but that it will 
be entirely removed during the present sum mer, and then the course 
of the river being open, it will generally remove all the avalanches 
that may fall at any future period ; or if a disastrous year like that of 
1816 gives rise to the formation of a new glacier, the means for its 
removal are known, and may be practised before the formation of 
another lake can again destroy the country. 
Vor. XVII. 
5S) 
ico] 
