First Article.
A few years ago a conjuror made his appearance in London, whose
performances were so wonderful that his audience, instead of being
confined to the foolish and thoughtless people who usually encourage
such exhibitions, included many of the most eminent philosophers and
scientific men of the day. It may naturally be supposed that his feats
must have been more than usually ingenious, to attract persons of such
consequence; and indeed many of them were so wonderful, that, had he
ventured to exhibit them a century or two ago, they would inevitably
have led him to the stake or the scaffold, for having too intimate
an acquaintance with a certain disreputable personage whom it is not
necessary to particularize by name. This great conjuror defied all the
ordinary laws of nature. He would not condescend to exhibit such vulgar
mountebank tricks as crunching red-hot coals in his mouth, and dining
on tenpenny nails; but he struck the faculty with the greatest horror,
by making poison of all kinds his common food; breakfasting on a strong
solution of arsenic, and taking a short drachm of prussic acid before
dinner, as a whet for his appetite. More wonderful still was his manner
of preparing this dinner: he used to have an oven heated intensely, every
day, into which he walked, or crawled, with the greatest composure,
taking with him a raw beef-steak, which in the course of seven or eight
minutes was well cooked by the intense heat of the place, whilst the only
effect of its high temperature on him was to quicken his pulse a little,
and produce a gentle perspiration. Fire, indeed, appeared his element,
and so perfectly could he control and master it, that he received almost
by acclamation the title of “the Fire King.”
Human greatness, however is but transitory, and even the laurels of the
Fire King were wrested from him by the envious doctors of the metropolis,
who wished him to drink prussic acid of _their own manufacture_, an
invitation which he very politely and prudently declined. But though on
this account suspicion was cast on his pretensions as a poison-drinker,
yet his reputation as a “Fire King” remained untarnished. He could
continue in an oven heated above the temperature at which water boils,
and he did so daily. There was no trick in this performance, for he
used to take raw eggs into the oven with him, and send them out to the
company, well done by the heat of the place alone. It was thought no
man could imitate his example. But however wonderful the feats of this
conjuror may appear to persons unacquainted with science, and while it
must be confessed they were performed with an appearance of daring and
temerity which certainly entitled the exhibitor to some degree of praise,
yet his performances were merely a striking illustration of the power
which every individual possesses of regulating the temperature of his own
body; and there was scarcely one person of his audience but might himself
have been the exhibitor, with very little training and with very little
courage.
Of all the functions of the human body one of the most wonderful is that
by which it maintains in every climate, and in every variety of season,
an almost equal temperature. It would appear to be necessary for the due
performance of the vital functions that this temperature should never
suffer any great degree of variation, and nature has accordingly provided
the means by which, when exposed to cold, the body can generate heat; and
when exposed to heat, so reduce its temperature that no inconvenience
shall result. Before considering the manner in which these very
different though equally necessary results are produced, it will not be
uninteresting to notice a few examples of the power of endurance shown by
human beings and the lower animals in regard to extremes of temperature.
In another paper we will endeavour to explain the cause.
One of the most striking and familiar of the laws of heat is what is
termed by philosophers “its tendency to an equilibrium.” For instance,
if a heated iron ball is suspended nearly in contact with one quite
cold, the former in a short time will have imparted so much of its heat
to the latter that they will soon become almost of equal temperature.
If a penny piece is thrown into a kettle of boiling water it will soon
become as hot as the boiling water itself. If a cup of water is exposed
to a temperature below 32 degrees, it parts with so much of its natural
heat, to come into a state of equilibrium with the medium in which it
is placed, that it is converted into ice. These and many more familiar
instances might be mentioned as illustrating the law of heat above
alluded to. In short, it may be received as one of the best established
facts in philosophy, that any substance, no matter what may be its
texture or natural qualities, provided it does not possess life, will
soon acquire and maintain the same temperature as that of the medium in
which it is placed, so long as it continues in that medium. A piece of
the metal platinum in the furnace of a glass-house may be kept at a white
heat for years; a similar piece of metal, in an ice-house, will remain
below 32 degrees so long as it is kept there.
It would be unnecessary to notice so particularly these well-known facts,
but that they will tend to render more striking the power which living
bodies possess of resisting the law to which all unorganized bodies are
subject. Any thing possessing life _can maintain a different temperature
to the medium in which it lives_. The natural heat of fishes is two or
three degrees above that of the water in which they live; the natural
heat of creatures which live within the bowels of the earth, like the
earth-worm for example, is as much above the usual temperature of the
earth; while man himself maintains the heat of his body, as shown by the
thermometer placed under the tongue or armpits, at about 98 degrees,
under every variety of season, and in every climate under the sun. Were
a human being to be kept imprisoned in an ice-house, the heat of his
body could never sink to 32 degrees (the freezing point) while life
remained. In these mighty reservoirs of ice and cold, the arctic regions,
the blood of the rude creatures who exist there is as warm as that of
ourselves; and at the torrid zone, where the heat of the sun is almost
insupportable, the animal heat of the human frame is only one or two
degrees higher than it is at the frozen poles.
The power of the superior animals, and especially of man, to resist
high degrees of temperature, is very extraordinary. The account of
the performances of the “Fire King” already noticed, is a sufficient
proof of this. Dr Southwood Smith, in his excellent treatise on “Animal
Physiology,” gives a far more interesting description, however, of the
accidental discovery of this property of life, from which we quote the
following particulars:--“In the year 1760, at Rochefoucault, Messrs
Du Hamel and Tillet, having occasion to use a large public oven on
the same day in which bread had been baked in it, wished to ascertain
with precision its degree of temperature. This they endeavoured to
accomplish by introducing a thermometer into the oven at the end of a
shovel. On being withdrawn, the thermometer indicated a degree of heat
considerably above that of boiling water; but M. Tillet, convinced that
the thermometer had fallen several degrees on approaching the mouth of
the oven, and appearing to be at a loss how to rectify this error, a
girl, one of the attendants on the oven, offered to enter and mark with
a pencil the height at which the thermometer stood within the oven.
The girl smiled at M. Tillet’s appearing to hesitate at this strange
proposition, and entering the oven, marked with a pencil the thermometer
as standing at 260 degrees of Fahrenheit’s scale. M. Tillet began to
express his anxiety for the welfare of his female assistant, and to
press her return. This female salamander, however, assuring him that she
felt no inconvenience from her situation, remained there ten minutes
longer, when at length, the thermometer standing at that time at 288
degrees, or 76 degrees above that of boiling water, she came out of the
oven, her complexion indeed considerably heightened, but her respiration
by no means quick or laborious. The publication of this transaction
exciting a great degree of attention, several philosophers repeated
similar experiments, amongst which the most accurate and decisive were
those performed by Doctors Fordyce and Blagden. The rooms in which these
celebrated experimenters conducted their researches were heated by flues
in the floor. There was neither any chimney in them, nor any vent for
the air, excepting through the crevice at the door. Having taken off
his coat, waistcoat, and shirt, and being furnished with wooden shoes
tied on with lint, Dr Blagden went into one of the rooms as soon as the
thermometer indicated a degree of heat above that of boiling water.
The first impression of this heated air upon his body was exceedingly
disagreeable, but in a few minutes his uneasiness was removed by a
profuse perspiration. At the end of twelve minutes he left the room, very
much fatigued, but no otherwise disordered. The thermometer had risen to
220 degrees; the boiling point is 212 degrees. In other experiments it
was found that a heat even of 260 degrees could be borne with tolerable
ease. At these high temperatures every piece of metal about the body
of the experimenters became intolerably hot; small quantities of water
placed in metallic vessels quickly boiled. Though the air of this room,
which at one period indicated a heat of 264 degrees, could be breathed
with impunity, yet of course the finger could not be put into the boiling
water, which indicated only a heat of 212 degrees; nor could it bear the
touch of quicksilver heated only to 120 degrees, nor scarcely that of
spirits of wine at 110 degrees. But in a physiological view, the most
curious and important point to be noticed is, that while the body was
thus exposed to a temperature of 264 degrees, the heat of the body itself
never rose above 101 degrees, or at most 102 degrees. In one experiment,
while the heat of the room was 202 degrees, the heat of the body was
only 99½ degrees; its natural temperature in a state of health being 98
degrees.”
A similar power of withstanding extreme degrees of temperature is one
of the peculiar properties of every thing possessing life. It is well
known that an egg containing the living principle possesses the power of
self-preservation for several weeks, although exposed to a degree of heat
which would occasion the putrifaction of dead animal matter. During the
period of incubation (hatching) the egg is kept at a heat of 103 degrees,
the hen’s egg for three, that of the duck for four weeks; yet when the
chick is hatched, the entire yolk is found perfectly sweet, and that
part of the white which has not been expended in the nourishment of the
young bird is also quite fresh. It is found that if the living principle
be destroyed, as it may be instantaneously, by passing the electric
fluid through the egg, it becomes putrid in the same time as other dead
animal matter. The power of the egg in resisting cold is proved to be
equally great by several curious experiments of Hunter, the celebrated
physiologist, which were so managed as to show at the same time both
the power of the vital principle in resisting the physical agent, and
the influence of the physical agent in diminishing the energy of the
vital principle. Thus he exposed an egg to the temperature of 17 degrees
of Fahrenheit’s thermometer, he found that it took about half an hour
to freeze it. When thawed, and again exposed to a cold atmosphere, it
was frozen in one half the time, and when only at the temperature of 25
degrees. He then put a fresh egg, and one that had previously been frozen
and again thawed, into a cold mixture at 15 degrees: the dead egg was
frozen twenty-five minutes sooner than the fresh one. It is obvious that
in the one case the undiminished vitality of the fresh egg enabled it to
resist the low temperature for so long a period; in the other case the
diminished or destroyed vitality of the frozen egg occasioned it speedily
to yield to the influence of the physical agent.
Animals can withstand the effects of heat far better than the severity of
cold. The human frame suffers comparatively little even in the burning
deserts of Arabia, compared with what it endures in those wastes of ice
and snow which form the polar regions. Here the body is stunted in its
growth; there is no energy of mind or character; and life itself is only
preserved by extraordinary care and attention. When a person is exposed
to intense cold, it produces partial imbecility; he neglects even those
precautions which may enable him to withstand its severity. He refuses
to exercise his limbs, without which they become torpid; and, unable to
resist the drowsiness that seizes on his frame, he resigns himself to its
influence, becomes insensible, and dies. Even in our own climate this is
not an unfrequent occurrence; and we cannot conclude this paper better
than by quoting the expressive lines of Thomson, describing the death of
an unhappy peasant from the severity of a winter storm:--
As thus the snows arise; and foul, and fierce,
All winter drives along the darkened air;
In his own loose revolving fields, the swain
Disaster’d stands; sees other hills ascend,
Of unknown joyless brow; and other scenes,
Of horrid prospect, shag the trackless plain:
Nor finds the river nor the forest, hid
Beneath the formless wild; but wanders on
From hill to dale, still more and more astray,
Impatient flouncing through the drifted heaps,
Stung with the thoughts of home; the thoughts of home
Rush on his nerves, and call their vigour forth
In many a vain attempt. How sinks his soul!
What black despair, what horror fills his breast!
When for the dusky spot, which fancy feign’d
His tufted cottage rising through the snow,
He meets the roughness of the middle waste
Far from the track and blest abode of man,
While round him might resistless closes fast,
And every tempest, howling o’er his head,
Renders the savage wildness more wild.
Then throng the busy shapes into his mind,
Of covered pits unfathomably deep,
A dire descent! beyond the power of frost;
Of faithless bogs; Of precipices huge
Smoothed up with snow; and what is land, unknown,
What water of the still unfrozen spring,
In the loose marsh or solitary lake,
Where the fresh fountain from the bottom boils.
These check his fearful steps; and down he sinks
Beneath the shelter of the shapeless drift,
Thinking o’er all the bitterness of death,
Mix’d with the tender anguish nature shoots
Through the wrung bosom of the dying man--
His wife--his children--and his friends unseen.
In vain for him the officious wife prepares
The fire, fair, blazing, and the vestment warm.
In vain his little children, peeping out
Into the mingling storm, demand their sire
With tears of artless innocence. Alas!
Nor wife, nor children more shall he behold--
Nor friends, nor sacred home. On every nerve
The deadly winter seizes; shuts up sense,
And, o’er his inmost vitals creeping cold,
Lays him along the snows, a stiffened corse,
Stretch’d out, and bleaching in the northern blast.