A Week a 
day’s sun, and any cause w should produce a slight-vibration 
of the air, would dislodge r masses above it, which were less 
firmly fixed than even th , and they would set the whole mass 
to tumbling headlong . This being spoken with so much 
earnestness, and in a mere whisper, I proceeded. Our valet de 
place, whom we had taken with us, was immediately before me, 
and being rather awkward, ‘moved very slowly, and had already 
made one or two false steps, which my guide seeing, advanced 
at once and stopped him, then told me to pass him, asa few more 
such steps might set some of the smaller blocks in motion, and 
as we were behind, we should lose our lives, by his stupidity. 
I passed him, and a few minutes’ walk carried us to the opposite 
side of this dangerous pass, where we sat down to rest and viewed 
from a point of safety the danger which we had almost uncon- 
sciously braved. It was now frightful to see other promontories 
of ice, which while we were crossing had been hidden from our 
view, resting upon mere feathery edges, with sheets of snow 
dispping over their edges in festoons, appeals scarcely thick 
enough to support their own weight. ‘+ 
Our guides told us we could now prove, or rather test, the 
truth of their assertions respecting the powerful effect of the 
vibration of the air at this height, which hint we at once availed 
ourselves of, by ordering the whole company to give three shouts 
at the height of their voices, which they did, and the effect of ©. 
which was quickly visible. The first shout produced no sensi- 
ble movement, but with the second, though the sound produced | 
hone of that sharp echo, which we often hear in the gorges of 
the mountain valleys, yet its eflect was manifest, first upon those 
festooned edges of snow which I have mentioned above, and 
which with another loud shout began to detach themselves in 
quick succession, falling in considerable sheets, till one of no 
great size fell some eighty feet, upon one of those huge rocks of 
ice, which was poised so equally that it required but the slightest 
oree to turn the balance, when this slid from its resting place, 
With but little Velocity, not as fast apparently as a man would 
Walk; but the momentum of so large a mass must have been 
éecemous: I should judge its slide was not more than twelve or 
fifteen feet (though it may have been many more) when being 
suddenly checked, by its base coming in contact with another 
mass, the momentum it had acquired in its slide threw its sum- 
