in the discharge of ordnance, le our dwellings. It may be 
more perfectly exemplified, by taking a bottle and corking it tight 
ly, and discharging at a short distance, twenty or thirty feet,a 
musket or a rifle, so that the ball shall pass about one inch over 
the cork ; the velocity of the projected bullet produces a vacuum, 
and the cork leaps from its place of confinement, in consequence 
of the atmospheric pressure being thus suddenly removed, and " 
the expansion of the air within the mantle. 
The Grand Mulets are two rocks which project from the Glace 
perpendicular, that the snow ‘does not rest wat thea Host * e 
halted for the night. a 
"They had loaded a cannon in the valley previous to our ap 
ture, and were to discharge it when they saw us (through theit 
telescope) arrive at this point, (Grand Mulets,) which they did, 
but neither myself nor the guides heard the report, although pee 
of our guides said they saw the smoke. 
I had taken up with me six old pigeons, the strongest ani 
shyest I could find in the pigeon-house of the hotel, and now de 
termined to let two of them off from the rock; the time being 
marked on a small piece of parchment, and attached by a string 
to one leg. I had desired the landlord to note the time when the 
pigeons made their appearance at Chamonix. I then tossed one 
of them a few feet in the air, that he might see to take his direc 
tion, when to my surprise, he fluttered a little, and came dowi 
nearly as rapidly as I had thrown him up. When we then a 
tempted to catch him, he endeavored to fly, but being unable 
to rise, he fluttered about, ran with his wings extended a few 
yards, and was easily taken. I presumed he might have been it 
jured by the confinement in the basket, and so I made the same 
experiment with three others, the result being the same; proving 
that the rarity of the air was too great to admit of their supporting 
themselves. But the next day in descending we let them 
about half way down between the Grand Mulets and the uppet 
point of vegetation, and they took their courses directly for Che 
monix, and were doubtless safely at home long before we reached 
the perpetual snow line. 
After resting here twenty minutes, and previous to eating, the 
average pulsations and respirations of the whole party stood @ 
one hundred and twenty eight of the former and thirty of the 
