NOTES ON EQUIPMENT
Our recent experiences having shown that the greatest altitude at which
acclimatisation takes place is about 22,000 feet above sea-level, it may
be reasonably assumed that, from the climber’s point of view, high
altitude on Mount Everest begins at that height. Incidentally, also, on
approaching the North Col over the East Rongbuk Glacier, the snow and
ice conditions met with up to this level approximate very closely to
summer conditions in the Alps. Above 22,000 feet, however, such
conditions, particularly the state of the snow, resemble those met with
in the Alps in mid-winter. This high-altitude zone may be further
divided into two sub-zones—the first, from 22,000 feet (the foot of the
steep snow and ice slopes leading up to the North Col) to 23,000 feet,
in which climatic conditions are by no means severe, as the North Col
affords protection from the prevailing west wind; and the second, from
23,000 feet onwards, of which extreme cold and strong wind are the
predominant characteristics.
It is therefore evident that the climber must be equipped according to
the zone in which he finds himself. In the first zone clothing somewhat
warmer than that used in the Alps in the summer is practically
sufficient. Owing to the marked intensity of the sun’s rays, however, it
is advisable to cover the trunk with at least one layer of sunproof
material, such as a sunproof shirt with spine pad, while a solar topee
and suitable snow-glasses constitute the best form of headgear. Crookes’
glasses of smoke-blue colour proved superior to other varieties; they
afford complete protection from glare and do not cause eye-strain and
subsequent headache. As sunburn, even very superficial and involving
only a small area, is invariably followed by conditions of feverishness
which must impair one’s fitness, a veil should be worn over the face and
gloves on the hands. Oxygen should be employed from the foot of the
North Col slopes onwards, for no useful purpose can be served by tiring
oneself through not using it, when, as we have seen elsewhere, full
recovery from fatigue is no longer possible at 23,000 feet. The second
zone (from 23,000 feet onwards), where a radical change in climatic
conditions is manifest, demands more complicated preparation. Wind is
seldom absent, and the degree of intensity of the cold is comparable
with that met with at the Poles, and indeed probably often exceeds it.
Also, owing to the rarefied state of the atmosphere, the cold is felt
much more severely than would be the case at sea-level. A far greater
volume of air is expelled from the climber’s lungs, and this air, at
blood heat and under a low pressure approximating to one-third of an
atmosphere, is saturated with moisture drawn from the body viâ the
lungs. The result is a proportionately far greater loss of animal heat.
Further, the partial pressure of oxygen contained in a normal atmosphere
becomes so low at altitudes over 23,000 feet that, unless the climber
has recourse to a supply of oxygen carried by himself, his climbing
efficiency is enormously reduced. The climbing equipment of the
mountaineer in this second zone of high altitude should therefore
include, firstly, a supply of oxygen; secondly, warm and windproof
clothing and foot-gear; thirdly, plenty of food and drink, as the use of
oxygen has a most stimulating effect upon the appetite.
The oxygen equipment has already been fully described by Mr. Unna in the
_Alpine Journal_, vol. xxxiv., page 235. The apparatus is, in principle,
quite simple. It consists of a frame carried on the shoulders of the
climber, at whose back, in a rack attached to the frame, are four steel
cylinders filled with oxygen compressed to 120 atmospheres. From the
cylinders the oxygen is taken by means of copper tubes over to an
instrument arm in front of the climber. This instrument arm, also
attached to the frame, carries the pressure gauges and so forth which
indicate how much oxygen the climber is left and how rapidly the
supplies are being used up. Close to the instrument arm and readily
accessible are the valves necessary for controlling the rate of flow of
oxygen from the apparatus. From the instrument arm the oxygen passes
through a flexible rubber tubing up to a mask covering the face of the
climber. The two types of mask supplied to the Expedition proved
useless, partly owing to their stifling effect upon the wearer, and
partly to the fact that saliva and moisture collected rapidly under them
and froze. Both, therefore, had to be discarded, but fortunately I was
able to make a substitute which functioned successfully. This mask
consists of a rubber tube into which is let a rubber bladder by means of
a glass T-piece, or by means of two straight pieces of glass tube let in
at opposite ends of the bladder. One end of the rubber tube is fastened
to the tube of the apparatus out of which the oxygen flows, the other
end being held in the climber’s mouth. On exhaling, the climber closes
the rubber tube by biting upon it, and the oxygen issuing from the
apparatus, instead of being wasted, is stored up in the rubber bladder.
On inhaling, the pressure of the teeth is released sufficiently to allow
the rubber tube to open, thus permitting the oxygen stored up in the
bladder to flow into the climber’s mouth, whence, mixing with the air
exhaled, it is drawn into the lungs. The chief advantages of this mask
are that, firstly, it economises oxygen to the greatest possible extent,
and secondly, the swelling and the shrinking of the bladder during each
exhalation and inhalation respectively give the climber a fair idea as
to how rapidly the oxygen is flowing from the apparatus, and thus
enables him to keep a check upon the readings of the flow-meter, or
instrument which indicates the rate of flow of gas. In actual practice
it was found that in the space of a few minutes the climber used the
mask quite automatically. The biting upon and closing the rubber tube
and subsequent opening were performed without mental effort.
A certain amount of breathing takes place viâ the pores of the skin. As,
however, the best clothing for a climber on Mount Everest is windproof,
there is a likelihood of the air surrounding the body becoming stale, in
which case the process of skin-breathing is seriously impeded. This
difficulty could be easily surmounted by flushing out the stale air by
means of a tube inserted inside the climber’s clothes, the flushing-out
process being done at intervals by temporarily fixing this tube to the
orifice of the oxygen apparatus. It is not known definitely whether the
advantage gained would be worth the trouble, but there is every reason
for believing so. In any case it is a matter which might well be
critically tested on the next Expedition.
Cigarette-smoking proved of great value at high altitudes. Geoffrey
Bruce, Tejbir, and I, after pitching camp at 25,500 feet, settled down
inside our little tent about 2.30 in the afternoon. From then until
seven o’clock the following evening we used no oxygen at all. At first
we noticed that unless one kept one’s mind on the question of
breathing—that is, made breathing a voluntary process instead of the
involuntary process it ordinarily is—one suffered from lack of air and a
consequent feeling of suffocation—a feeling from which one recovered by
voluntarily forcing the lungs to work faster than they would of their
own accord. There is a physiological explanation for this phenomenon. At
normal altitudes human blood holds in solution a considerable quantity
of carbon dioxide, which serves to stimulate the nerve centre
controlling one’s involuntary breathing. At great altitudes, however,
where, in order to obtain a sufficiency of oxygen, the climber is forced
to breathe enormous volumes of air, much of this carbon dioxide is
washed out of the blood, and the nerve centre, no longer sufficiently
stimulated, fails to promote an adequately active involuntary breathing.
A voluntary process must be substituted, and this throws a considerable
strain upon the mind, and renders sleep impossible. On smoking
cigarettes we discovered after the first few inhalations it was no
longer necessary to concentrate on breathing, the process becoming once
more an involuntary one. Evidently some constituent of cigarette smoke
takes the place and performs the stimulating function of the carbon
dioxide normally present. The effect of a cigarette lasted for about
three hours. Clothing is a most important matter. It would be difficult
to exaggerate the intensity of the cold encountered at high altitudes on
Mount Everest. Several layers—the innermost of which should be of silk,
the others wool of moderate weight—form a much better protection against
cold than one or two heavy layers. The chief item of clothing, however,
should consist of a jumper and trousers made of windproof material. Two
of these windproof suits should be worn one above the other, and every
precaution taken to reduce the circulation of the air to the smallest
possible extent. The hands must be protected in accordance with the same
principles, and the head. I used a R.N.A.S. pattern flying helmet and
found it most satisfactory. Helmet and snow-glasses should completely
cover the head and face, leaving no skin exposed. Boots were a source of
trouble to all, but fortunately we had so many different designs which
we could test out thoroughly that we are now able to form a very shrewd
idea as to which kind is the most suitable. Leather conducts heat too
well for reliance to be placed upon it for the preservation of warmth.
The uppers of the boots should be of felt, strengthened where necessary
to prevent stretching, by leather straps covered by duroprened canvas.
Toe and heel caps must be hard and strong, and the former especially
should be high, so that the toes are given plenty of room. The sole of
the boot should be composed of a layer of thin leather attached to a
layer of three-ply wood, hinged in two sections at the instep. A thin
layer of felt should form the inside of the sole. The boots should be
large enough to accommodate in comfort two pairs of thick socks, or,
even better still, two pairs of thin socks and one pair of thick socks.
Nails used in the boots should penetrate through the leather into the
three-ply wood, but not through the latter.
In conclusion, I should like to thank the Governing Body of the Imperial
College of Science and Technology for granting me the necessary leave to
enable me to take part in the 1922 Mount Everest Expedition, and also
for granting me facilities for carrying out a considerable number of
investigations in the laboratory of the Department of Chemical
Technology upon questions relating, amongst others, to oxygen equipment,
fuels, and vacuum flasks. These last were required in order to enable us
to keep foods liquid at heights over 23,000 feet, and the flasks
obtained on the market proved quite useless for this purpose in view of
the fact that they had not been sufficiently well evacuated.
------------------------------------------------------------------------
THE THIRD ATTEMPT
By
GEORGE LEIGH-MALLORY
------------------------------------------------------------------------