By Dr. B.W. RICHARDSON.

During the seven weeks of extreme atmospheric cold in which the last year ended and with which the present year opened, every one has been startled by the mortality that has prevailed among the enfeebled and aged population. Friends have been swept away in a manner most painful to recall, under the influence of an external agency, as natural as it is fatal in its course, and over which science, as yet, holds the most limited control.

In the presence of these facts questions occur to the mind which have the most practical bearing. Why should a community wake up one day with catarrh or with the back of the throat unduly red and the tonsils large? Why, in a particular village or town, shall the medical men be summoned on some particular day to a number of places to visit children with croup? What is the reason that cases of sudden death, by so-called "apoplexy," crowd together into a few hours? Why, in a given day or week, are shoals of the aged swept away, while the young live as before? These are questions which curative and preventive medicine have not yet mastered as might be desired. Curative medicine, at the name of them, too often stands abashed, if her interpreter be honest; and preventive medicine says, if her interpreter be honest, "The questions wait as yet for full interpretation."

Still, we are not altogether ignorant; some circumstances appear to be followed by effects so definite, that we may almost consider we have before us, in true position, cause and effect. Let us look at this position in reference to the simple influence of temperature on the value of life.

If we observe the fluctuation of the thermometer by the side of the mortality of the nation at large, no calculable relationship seems, at first sight, to be traceable between the one and the other. But if, in connection with the mortality, care be taken to isolate cases, and to divide them into groups according to the ages of those who die, a singular and significant series of facts follow, which show that after a given age a sudden decline of the temperature influences mortality by what may be considered a definite law. The law is, that variations of temperature exert no marked influence on the mortality of the population under the age of thirty years; but after the age of thirty is reached, a fall of temperature, sufficient to cause an increased number of deaths, acts in a regular manner, as it may be said, in waves or lines of intensity, according to the ages of the people. If we make these lines nine years long, we discover that they double in effect at each successive point. Thus, if the, fall in the temperature be sufficient to increase the mortality at the rate of one person of the age of thirty, the increase will run as follows: 1 death at 30 years of age will become 2 deaths at 39 years of age, 4 at 48 years, 8 at 57 years, 16 at 66 years, 33 at 75 years, and 64 at 84 years.

In these calculations nothing seems to be wanting that should render them trustworthy; they resulted from inquiries conducted on the largest scale; they were computed by one of our greatest authorities in vital statistics, the late Dr. William Farr, and they accord with what we gather from common daily observation. They supply, in a word, the scientific details and refinements of a rough estimate founded on universal experience, and they lead us to think very gravely on many subjects which may not have occurred to us before, and which are as curious as they are important.

We often hear persons who know little about vital phenomena, by which term I mean nothing mysterious, but simply the physics embraced in those phenomena which we connect with form and motion under the term life, harping on the one string, that man knows nothing of the laws of life and death. But what an answer to such presumption do the facts rendered above supply. Life and death are here reduced, on given conditions, to reasonings as clear and positive as are the reasonings on the development of heat by the combustion of fuel. It is not necessary for the vital philosopher to go out into the towns and villages to take a new census of deaths to enable him to give us his readings of the general mortality under the conditions specified. He may sit in his cabinet, and, as he reads his thermometer day by day, predict results. There is a fall of temperature that shall be known by experience to be sufficiently deep and prolonged to cause an increase of one death among those members of the community who have reached thirty years. Then, rising by a definite rule, there have died sixty-four, in proportion to that one, of those who have reached eighty-four years. This is sound calculation, and it leads to reflection.

It leads one to ask, what, if the law be so definite, are curative and preventive medicine doing meanwhile, that they shall not disturb it? I fear that they hardly produce perturbations, and I do not see why they should; because, as the truth opens itself to the mind, the tremendous external change in the forces of the universe that leads to the result, is not to be grappled with nor interfered with by any specific method of human invention. The cause is too general, too overwhelming, too grasping. It is like the lightning stroke in its distance from our command; but it is widely spread, not pointed and concentrate; prolonged, not instantaneous; and, by virtue of these properties, is so much the more subtile and devastating.

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.