due to the dilatation of the air contained in that organ.
Such are the all but invariable effects of high elevations;
varying with most persons according to the suddenness
and steepness of the ascent, the amount and duration
of exertion, and the length of time previously passed at
great heights. After having lived for some weeks
at Momay where I was relieved of upwards of six tons
of pressure (!), I have thence ascended several times
to 18,500j and once above 19,000 feet, without any
sensations but lassitude and quickness of pulse; hut in
these instances it required great caution to avoid
painful symptoms. Residing at Momay, however, my
functions were wholly undisturbed; nor could I detect
any quickness of pulse or of respiration when the
body was at rest, below 17,000 feet.
Not only is the frame of a transient visitor unaffected
(when at rest) by the pressure on his body being
reduced from 30,000 to 13,000 pounds, but the Tibetan,
bom and constantly residing at upwards of 14,000
feet, differs in no respect that can be attributed to
diminished pressure, from the native of the level of
the sea. The average duration of life, and the amount
of food and exercise is the same ; eighty years are
rarely reached by either. The Tibetan, too, however
inured to cold and great elevations, still suffers when
he crosses passes 18,000 or 19,000 feet high, and
apparently neither more nor less than I did.
Liebig remarks (in his “ Animal Chemistry 1j that in
an equal number of respirations, we consume a larger
amount of oxygen at the level of the sea than on a
mountain; and it can he shown that under ordinary
circumstances at Dorjiling, 20T4 per cent less is
inhaled than on the plains of India. Yet the chest
cannot expand so as to inspire more at once, nor is the
respiration appreciably quickened; by either of which
means nature would be enabled to make up the deficiency.
I t is true that it is difficult to count one’s own
respirations, but the average is considered in a healthy
man to be eighteen in a minute; in my own case it
is sixteen, an acceleration of which by three or four
could not have been overlooked, in the repeated trials I
made at Dorjiling; and still less the eight additional
inhalations required at 15,000 feet to make up for the
deficiency of oxygen in the air of that elevation.
I t has long been surmised that an alpine vegetation
may owe some of its peculiarities to the diminished
atmospheric pressure; and that the latter being a
condition which the gardener cannot supply, he for
this reason seldom successfully cultivates such plants.
I know of no foundation for this hypothesis; many
plants, natives of the level of the sea in other parts
of the world, and some even of the hot plains of
Bengal, ascend to 12,000 and even 15,000 feet on the
Himalaya, unaffected by the diminished pressure.
A great number of species from low countries may be
cultivated, and some have been for ages, at 10,000 to
14,000 feet without change. I t is the same with the
lower animals; innumerable instances may with ease
be adduced of pressure alone inducing no appreciable
change, whilst there is absence of proof to the contrary.
The phenomena that accompany diminished
pressure are the real obstacles to the cultivation of