Chapter 5

At first it seems easy to explain the reason why a sudden fall in temperature should lead to an increase in the number of deaths, and it is to be admitted that, to a certain extent, the reason is clear.

ANIMAL POWER AT DIFFERENT PERIODS OF LIFE.

Without entering on the question whether heat is the animating principle of all living organisms, we may accept that in the evolution of heat in the body we have a measurement of the capacity of the body to sustain motion, which is only another phrase for expressing the resistance of the body to death. For example, if we assume that a healthy man of thirty respires sufficient air per day to produce as much heat as would raise fifty pounds of water at 32° Fahr. to 212° Fahr., and if we assume that a man of sixty in the same temperature is only able to respire so much air as shall cause him to evolve so much heat as would raise forty pounds of water from 32° to 212°, we see a general reason why the older man should feel an effect from a sudden change in the temperature of the air which the younger would not feel; and if we assume, further, that a man of eighty could in the same time produce as much heat as would raise only twenty pounds of water from 32° to 212°, we see a good reason why the oldest should suffer more from a decrease of external temperature than the other two. It is necessary, however, to know more than this general statement of an approximate fact; we ought to understand the method by which the reduction of temperature influences, and the details of the physiological process connected with the phenomena. When a human body is living after the age when the period of its growth is completed and before the period of its decay has commenced, it produces, when it is quite healthy, by its own chemical processes, so much heat or force as shall enable it, within given bounds, (1) to move its own machinery; (2) to call forth, at will, a limited measure of extra force which has been lying latent in its organism; and (3) to supply a fluctuating loss that must be conveyed away by contact with the surrounding air, by the earth, and by other bodies that it may touch, and which are colder than itself. There is thus produced in the body, _applied_ force, _reserve_ force, and _waste_ force, and these distributions of the whole force generated, when correctly applied, maintain the perfect organism in such balance that life is true and steady. So much active force carries with it the power to perform so much labor; so much reserve force carries with it the power to perform a measure of new or extra labor to meet emergencies; so much waste force enables the body to resist the external vicissitudes without trenching on the supply that is always wanted to keep the heart pulsating, the chest breathing, the glands secreting or excreting, the digestive apparatus moving, and the brain thinking or absorbing.

Let us, even in the prime of manhood, disturb the distribution of force ever so little, and straightway our life, which is the resultant of force, is disturbed. If we use the active force too long, we become exhausted, and call on the reserve; if we continue the process, the result is failure more or less perfect, sleep, and, in the end, the last long sleep. Let us, instead of exhausting the force, cut it off at the sources where it is generated; let us remove the carbon or coal that should go in as fuel food, and we create prostration, and in continuance a waning animal fire, sleep, and death; or let us, instead of removing or withdrawing the supply of fuel, cut off the supply of air, as by immersion of the body in water, or by making it breathe a vapor that weakens the combination of oxygen with carbon--such a vapor as chloroform--and again we produce, at once, prostration, sleep, or death, according to the extent to which we have conducted the process. Lastly, if instead of using up unduly the active and reserve force, or of suppressing the evolution of force by the withdrawal of its sources, we expose the body to such an external temperature that it is robbed of its heat faster than it can generate it; if to supply the waste heat we draw upon the active and reserve forces, we call forth immediately the same condition as would follow extreme over-exertion, or suppression of the development of force; we call forth exhaustion and sleep, and, if we go far enough, death.

We have had in view, in the above description, a man in the prime of life, in the center of growth, and decay. In regard to the force of animation in him, let us look at him now retrospectively and prospectively. In the past his has been a growing, developing body, and in the course of development he has produced an excess of force commensurate with the demands of his growth; this has enabled him gradually to bear more fatigue and more exposure, without exhaustion, and even with ease, until he has reached his maximum. When he has stopped in development, when he stands on a fair level with the external forces that are opposed to him, then his own force, for a short time balanced, soon stands second in command. He feels cold more tenderly; if his rest be broken, the demand for artificial heat is more urgent; if he lose or miss food, he sinks quickly; and, returning to our facts, as to the influence of the external temperature on mortality, these are the reasons why a fall in the thermometer sweeps away our population according to age so ruthlessly and decisively.

If we analyze the facts further by the side of the diseases which kill the old, we find those diseases to be numerous in name, but all of two types. They are diseases which of themselves tend either to produce undue loss of force, or that tend to prevent the development of force at its origin. Thus affections which are accompanied with exhaustive loss of fluids from the body, such as diabetes, dropsies, and hæmorrhages, are of the first class; affections in which due supply of air to the lungs is prevented are of the second class, especially bronchitis, a disease so commonly assigned as the cause of the deaths among the members of the aged and enfeebled population, that succeed immediately on an extreme fall of the thermometer.

FALL OF TEMPERATURE--MODE OF ACTION.

In what has been written above I have stated simply and in open terms the fact that the fall of temperature produces a specified series of results, by reducing the force of the living organism, and disposing it to die. We may from this point investigate, from a physiological point of view, the mode by which the effect is produced in the economy. How does the decline of temperature act? Is the process simple or compound?

EXTRACTION OF HEAT.

The process is compound, and into it there enter three elements. In the first place, the body is robbed rapidly of its waste force, and the reserve and active elements of force are, consequently, called upon to the depression of the organism altogether. This obtains because the medium surrounding the body, the air, unless it be artificially heated, removes from its contact with the body a larger proportion of heat than can be spared; and it might be possible to produce such an influence on the body by sudden extraction of its heat as to destroy it at once by the mere act. If a man could be surrounded with frozen mercury he would die instantaneously, as from shock, by the immediate extraction of his heat. But in ordinary cases, and under ordinary circumstances, the mere rapid extraction of waste heat is not sufficient to account for all the mischief produced by a low temperature; for by artificial warmth and non-conducting garments, we counteract the influence, and that, too, in a manner which proves pretty successful. We may, therefore, leave this element of extraction of heat as a most important, but not as the sole, agent of evil.

SUPPRESSED OXIDATION.

The second element is the effect on the process of oxidation of blood under the influence of cold. We all are aware that if a portion of dead animal or vegetable matter be placed at a low temperature, it keeps for a considerable time; and we have evidence of dead animals which, clothed in thick ribbed ice, have been retained from putrefaction for centuries. Hence we say that cold is an antiseptic as alcohol is, and chloroform, and ammonia, and other similar bodies. Cold is an antiseptic then, but why? Because it prevents, even in the presence of a ferment, the union of oxygen gas with combustible matter. The molecules of oxygen, in order that they shall combine, and in their combination evolve heat, require to be distributed, and to be distributed by the form of motion known as heat; deprive them of this activity, and they come into communion with themselves, are attracted to each other, and lose to the extent of this attraction their power of combining with the molecules of other bodies for which they have an affinity. In an analogous, but more obvious way, we may see the same effect of motion in the microscopic examination of blood. In the blood, while it is circulating briskly in its vessels, there are distributed through it, without contact with each other, the millions of oxygen carriers called blood corpuscles. In the circulation in the free channels of the body, the arteries and veins, it is motion that keeps these corpuscles apart; we draw a drop of blood and let it come to rest on the microscope glass, and as the motion ceases the separated corpuscles run together, and adhere so firmly that we cannot easily separate them without their disintegration. If we were able to drive them in this state round the body, through the vessels, they would not combine readily with the tissues; they have, in fact, forfeited the condition necessary for such combination. So with the oxygen they carry; when its invisible molecules are deprived of the force called heat, which is motion, they do not readily combine with new matter. But perfect combination of oxygen and carbon in the blood is essential to every act of life. In the constant clash of molecule of oxygen with molecule of carbon in the blood lies the mainspring of all animal motion; the motion of the heart itself is secondary to that. Destroy that union, however slightly, and the balance is lost, and the animal body is, in a plain word, _ill_.

Cold or decreased temperature, below a given standard, which for sake of comparison we may take at a mean of 40° Fahr., reduces this combination of oxygen and carbon in blood. In my Lettsomian lectures to the Medical Society of London, delivered in 1860, I entered very fully into this subject, and illustrated points of it largely by experiment. Since then I have done more, and although I have not time here to state the details of these researches, I will epitomize the principal facts. I found then that, by exposing blood in chambers into which air can pass in and out, the blood could be oxidized at temperatures of 70° if the distribution of air and blood were effectually secured, and I also found a proper standard of oxidation from a proper temperature. Afterward I proceeded to test for combination at lower temperatures, and discovered a gradually decreasing scale until I arrived at 40° Fahr., when efficient combination ceased. Of course, my method was a very crude imitation of nature, but it was sufficient to show this fair and reliable result, that the oxidation of blood decreases as the temperature of the oxygen decreases.

From this point I went to animal life itself. I exposed animals to pure cold oxygen and to cold atmospheric air, and compared the results with other experiments in which animals of similar weight were exposed to warm air and warm oxygen. The facts gleaned were most important, for they proved conclusively that the products of combustion, that is to say, the products resulting from the union of oxygen and carbon, were reduced in proportion as the temperature of the oxygen was reduced. In the course of this inquiry another singular and instructive fact was elicited. It has been long known that at ordinary temperature, say 60°, pure neutral oxygen does not support animal life so well as oxygen that is diluted with nitrogen. In the nitrogen the molecules of oxygen are more freely distributed under the influence of motion, that is the meaning of the observed fact. What, then, would be the respective influence of low and high temperatures on the respiration of pure oxygen? To settle this question, animals of the same size and weight were placed in equal measures of oxygen gas and common air at a temperature of 30° Fahr., and with the inevitable result that the animal in the pure oxygen ceased to respire one-third sooner than did the animal in common air. Carrying the inquiry further, I found that if the oxygen gas were warmed to 50° Fahr., the respiration was continued six times as long as in the previous experiment, while if the warming were carried to 70°, it was sustained twenty-four times as long. I reversed the experiment; I made oxygen with cold produce anæsthetic sleep in a warm-blooded animal.

I need not carry this argument further; it is the easiest of the demonstrative facts of physiological science that reduction of temperature lessens the combining power of oxygen for blood, and therewith causes a reduction of animal force, and a tendency to arrest of that force, which, in the end, means _death_.

MECHANICAL COLD.

The third element in the action of cold is more purely mechanical, and this, though in a sense secondary, is of immense import. When any body, capable of expansion by heat, that is to say, by radiant motion of its own particles, is reduced in temperature, it loses volume, contracts, or shrinks. The animal body is no exception to this rule; a ring that will fit tightly to the warm finger will fall off the same finger after exposure to cold. The whole of the soft parts shrink, and the vessels contract and empty themselves of their blood. Cold applied to the skin in an extreme degree blanches the skin, and renders it insensible and bloodless, so that if you prick it it does not bleed, neither does it feel. In cases where the body altogether is exposed to extreme cold this shrinking of the external parts is universal; the whole surface becomes pale and insensible; the blood in the small vessels superficially placed is forced inward upon the heart and vessels of the interior organs; the brain is oppressed with blood; sleep, or coma, as it is technically called, follows, and at last life is suspended.

In exposure to the lowest wave of temperature in this country these extreme effects are not commonly developed; but minor effects are brought out which are most significant. In particular, the effect on the lungs is strongly marked. The capillary vessels of the lungs, making up that fine network which plays over the computed six hundred millions of air vesicles, undergo paralysis when the cold air enters, and in proportion as such obstruction from this cause is decisive, the blood that should be brought to the air vesicles is impeded, and the process of oxidation is mechanically as well as chemically suppressed. The same contraction is also exerted on the vessels of the skin, driving the blood into the interior and better protected organs. Hence the reason why on leaving a warm room to enter a cold frosty air there is an immediate action of the visceral organs from pressure of blood on them, and not unfrequently a tendency to diarrhoea from temporary congestion of the digestive tract. Three factors are at work, in fact, whenever the low wave of temperature affects the animal body; abstraction of heat from the body, beyond what is natural; arrest of chemical action and of combustion; paralysis of the minute vessels exposed to the cold.

COMBINED EFFECTS.

We cannot view the extent of change in the organic life induced by the low wave of heat without seeing at once the sweep of mischief which exposure to the wave may effect. It exerts an influence on healthy life in the middle-aged man, and I know of no disease which it does not influence disastrously. Is the healthy man exhausted, it favors internal congestion; has he a weak point in the vascular system of his brain, it renders that point liable to pressure and rupture, with apoplexy as the sequence; is he suffering from bronchial disease, and obstruction, already, in his air passages, here is a means by which the evils are doubled; has he a feeble, worn-out heart, it is unable to bear the pressure that is put upon it; has he partial obstruction of the kidney circulation, he is threatened with complete obstruction; is he indifferently fed, he is weakened generally. It is from this extent of action that the mortality of all diseases runs up so fast when the low wave of heat rolls over the population, affecting, as we have seen, the feeblest first.

Another danger sometimes follows which is remote, but may be fatal, even to persons who are in health. It is one of the best known facts in science that when a part of the surface of the body has been exposed long to cold, the greatest risk is run in trying suddenly to warm it. The vessels become rapidly dilated, their coats relax, and extreme congestion follows. But what is true of the skin is true equally, and with more practical force, of the lungs. A man, a little below par, goes out when the wave of temperature is low, and feels oppressed, cold, weak, and miserable; the circulation through his lungs has been suppressed, and he is not duly oxidizing; he returns to a warm place, he rushes to the fire, breathes eagerly and long the heated air, and adds to the warmth by taking perchance a cup of stimulant; then he goes to bed and wakes in a few hours with what is called pneumonia, or with bronchitis, or with both diseases. What has happened? The simple physical fact of reaction under too sudden an exposure to heat after exposure to cold. The capillaries of the lungs have become engorged, and the circulation static, so that there must be reaction of heat, inflammation, before recovery can occur. Nearly all bronchial affections are induced in this manner, not always nor necessarily in the acute form, but more frequently by slow degrees, by repetition and repetition of the evil. Colds are often taken in this same way, from the exposed mucous surfaces of the nose and throat being subjected first to a chill, then to heat.

The wave of low temperature affecting a mixed population finds inevitably a certain number of persons of all ages and conditions on whom to exert its power. It catches them too often when they least expect it. An aged man, with sluggish heart, goes to bed and reclines to sleep in a temperature, say, of 50° or 55°. In his sleep, were it quite uninfluenced from without, his heart and his breathing would naturally decline. Gradually, as the night advances, the low wave of heat steals over the sleeper, and the air he was breathing at 55° falls and falls to 40°, or it may be to 35° or 30°. What may naturally follow less than a deeper sleep? Is it not natural that the sleep so profound shall stop the laboring heart? Certainly. The great narcotic never travels without fastening on some victims in this wise, removing them, imperceptibly to themselves, into sleep ending in absolute death.

SOME SIMPLE RULES.

The study of the physiological influence of the wave of low temperature, and of its relation to the wave of mortality, suggests a few rules, simple, and easily remembered.

1. Clothing is the first thing to attend to. To have the body, during variable weather, such as now obtains, well enveloped from head to foot in non-conducting substance is essential. Who neglects this precaution is guilty of a grievous error, and who helps the poor to clothe effectively does more for them than can readily be conceived without careful attention to the subject we have discussed.

2. In sitting-rooms and in bedrooms it is equally essential to maintain an equable temperature; a fire in a bedroom is of first value at this season. The fire sustains the external warmth, encourages ventilation, and gives health not less than comfort.

3. In going from a warm into a cold atmosphere, in breasting the wave of low temperature, no one can harm by starting forth thoroughly warm. But in returning from the cold into the warm the act should always be accomplished gradually. This important rule may readily be carried in mind by connecting it with the fact that the only safe mode of curing a frozen part is to rub it with ice, so as to restore the temperature slowly.

4. The wave of low temperature requires to be met by good, nutritious, warm food. Heat-forming foods, such as bread, sugar, butter, oatmeal porridge, and potatoes, are of special use now. It would be against science and instinct alike to omit such foods when the body requires heat.

5. It is an entire mistake to suppose that the wave of cold is neutralized in any sense by the use of alcoholics. When a glass of hot brandy and water warms the cold man, the credit belongs to the hot water, and any discredit that may follow to the brandy. So far from alcohol checking the cold in action, it goes with it, and therewith aids in arresting the motion of the heart in the living animal, because it reduces oxidation.

6. Excessive exercise of the body, and overwork either of body or of mind, should be avoided, especially during those seasons when a sudden fall of temperature is of frequent occurrence. For exhaustion, whether physical or mental, means loss of motion in the organism; and loss of motion is the same as loss of heat.

One further consideration, suggested by the subject of this paper, has reference to the bearing of the public toward the labors of the medical man in meeting the effects of the low wave of heat. The public, looking on the doctor as a sort of mystical high priest who ought to save, may often be dissatisfied with his work. Let the dissatisfied think of what is meant by saving when there is a sudden fall in the thermometer. Let them recall that it is not bronchitis as a cause of death, nor apoplexy, nor heart disease, as such, that the doctor is called on to meet; but an all-pervading influence which overwhelms like the sea, and against which, in the mass, individual effort stands paralyzed and helpless. When the doctor is summoned the mischief has at least commenced, and, it may be, is so far over that treatment by mere medicines sinks into secondary significance. Then he, true minister of health, candid enough to bow humbly before the great and inevitable truth, and professing no specific cure by nostrum or symbol, can only try to avert further danger by teaching elementary principles, and by making the unlearned the participators in his own learning.--_The Asclepiad._

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THE TREATMENT OF GLAUCOMA.

As this disease is so fatal to vision, any remedy that may be suggested to diminish the frequency of its termination in blindness cannot fail to be read of with interest. M. Nicati, in the _Revue generate de clinique et de therapeutique_, has had marked success in the treatment of glaucoma by drainage of the posterior chamber, either by sclerotomy or by sclero-iritomy, as the conditions of the individual case may require.--_N.Y. Med. Jour._

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A TWIN SCREW LAUNCH RUN BY A COMPOUND ENGINE.