Jean-Charles Rodolphe Radau

“ Both clothing and the house have been invented to protect us; but a very common error, which has given rise to many mistakes, has been to regard the house and the clothing as designed essentially to isolate us from the external air. The truth is, that they are simply regulators of our indispensable and constant relations with the ambient atmosphere. These relations can not well be comprehended unless we take account of the complex phenomena by which the temperature of the body is kept up in the midst of the most diverse influences. ”

“ But thought never springs instantaneously under the influence of an external cause; an appreciable time elapses, one or two tenths of a second, before an idea is aroused in the mind in consequence of an impression received by the brain, and before it will respond to that idea by the movement of a limb. So the nervous current which transmits sensations to the brain, and bears the commands of the will to the extremities of the body, requires a certain time to finish its course. Impressions coming to us from without are not perceived at the very instant of their production ”

“ Indeed, do not earthquakes—whose cause may be found as well in the falling of masses of rock, or the action of subterranean waters, as in purely volcanic phenomena—constantly show that great changes are occurring in the depths of the ground?
Sir George Airy has lent the weight of his great authority to the hypothesis of a liquid nucleus, in his recent interesting address at Cockermouth, before an audience of miners and others. The illustrious astronomer royal holds the opinion that the earth's crust is formed of more or less compact rocks that float on a mass of fluid or semifluid lava. ”

“ We know that animal heat is produced by chemical changes that are accomplished in the tissues, and principally, but not exclusively, by the combustion of the food which is assimilated and brought into the circulation, where the inspired oxygen transforms it into alcohol and carbonic acid. This combustion raises the temperature of the blood, and the warm liquid, which penetrates everywhere, warms the organism almost in the same way that a house is heated by hot-water pipes. ”

“ There are formed around the bodies of furred animals superimposed strata of air, the temperature of which diminishes from the skin to the ends of the hairs; and in winter the animals seem cold to the touch, while the zone of exchanges retires toward the skin as the cold becomes more intense. The body of the animal is, then, cooled principally by convection and by the ventilation which incessantly removes the heated air. When the atmosphere is much agitated the cold penetrates more readily through the furs, and also through our overcoats, as all know who have been much exposed to cold winds. ”

“ The agreeable refreshment the shadow of the woods gives us is due to the relatively low temperature produced in the trees by their faculty of evaporation, and the facility it affords for promoting radiation from the skin. The body is also cooled by convection, or by giving off its heat to the air that bathes it, and this loss is more sensible in proportion as the air is cooler and more frequently renewed. The atmosphere is always in motion, even when apparently most calm; and thousands of its movements escape our senses, because they are not strong enough to impress our organs. ”

“ But assuming that solidification commences at the surface, a thin skin will first be formed, and this being by the hypothesis heavier than the liquid it covers—since its volume shrinks in solidifying—it follows that it must be broken up and the fragments be carried to the bottom or center, forming there a solid nucleus. Thus, in any event, solidification will occur at the center, and, when the entire mass has acquired a temperature near the point of solidification, a solid carapace will gradually cover the surface, beneath which here and there masses of liquid will still exist. ”

“ There is a limit at every degree of temperature to the proportion of vapor which the air can contain; and the interval between the points of dryness and of saturation increases with the temperature. An atmosphere at the same time very moist and very hot seems heavy to us because it hinders the evaporation of the water that transpiration brings to the surface of the body. This is why hot and moist climates are so much more unhealthy than hot and dry ones. ”

“ We will first suppose that the entire mass of the globe yields to the attracting forces as readily as if it were liquid. In this case sea and solid land will be raised alike, and, the surface of the sea always being at the same distance from the bottom, no tides will be seen. Granting that the average rigidity of the globe's mass is comparable to that of glass, we see that it must undergo a change of form equal to 0·6 of that which it would experience if it were liquid ”

“ It is not necessary, indeed, to assume so great a depth as twenty kilometres for the seat of this force, in order to explain the existence of matter in fusion, for there is nothing to militate against the supposition that the earth's crust is thinner in volcanic regions than elsewhere. It is quite probable that the inner surface of this crust is furrowed and fissured, especially along the lines of unequal density where the continents join the ocean-beds.
The quantity of lava that a volcano emits during an eruption surpasses anything we can imagine. ”

“ The thinnest veil is a vestment in the sense that it moderates the loss of heat which radiation causes the naked body to experience. In the same way a cloudy sky protects the earth against too great cooling in spring nights. In covering ourselves with multiple envelopes of which we augment the protecting thickness according to the rigor of the seasons, we retard the radiation from the body by causing it to pass through a series of stages, or by providing relays. The linen, the ordinary dress, and the cloak constitute for us so many artificial epidermises. ”

“ It will be evident that an exact knowledge of the figure of the earth has an important bearing on any hypothesis of the internal constitution of our planet. Geodesy, that science that may be called surveying on a grand scale, and which takes for its bases of measurement at once the earth and the heavens, has not yet completed its work. ”

“ Mines and wells have barely scratched the solid crust that conceals the mysteries of the earth's depths. Our vague and uncertain ideas regarding the condition of the interior of the earth are based on analogies and inductions from facts observed on its surface or in the heavens. Very little light do we get on this subject from direct experiment. The bowels of the earth are not, indeed, easily accessible. ”

“ In considering the prodigious effects of volcanic eruptions and earthquakes, the secular oscillations of the ground, the changes of the earth's surface even in our day by the action of the sea and of rivers, the partisans of uniformity in geological changes reject the theory of cataclysms, as held by the opposite school. Still, it can not be denied that the earth has grown old, and that its energy must have diminished. ”

“ The heat that leaves the skin goes to warm these superposed envelopes; it passes through them the more slowly in proportion as they are poorer conductors; reaching the surface, it escapes, but without making us feel the chills which direct contact with the atmosphere occasions, for our clothes catch the cold for us. The hairs and the feathers of animals perform the same function as toward their skin, serving to remove the seat of calorific exchange away from the body. The protection we owe to our clothes is made more effectual by their always being wadded with a stratum of warm air. ”

“ The body, even when exposed stark naked to the air, is not wholly without defense against heat and cold. It can, up to a certain point, itself regulate the expenditure of caloric by the intervention of the vaso-motor nerves that go to the capillaries of the skin. Cold provokes a shrinking of the little vessels, and, restraining the peripheric circulation, diminishes the radiation and the transpiration to such a degree as to protect the internal organs for a considerable time. ”

“ We have more exact data concerning the eruption of Coseguina, a small volcano of Central America, which, in 1835, rained pumice-stone on the land and sea over a radius of fifteen hundred kilometres, and discharged daily not less than fifty milliards of cubic metres. When we consider the stupendous force required to raise and throw to a distance such volumes of matter, it is difficult to believe that the underground forces that feed the volcanoes, and which we know have been active from a very remote period, are mere accumulations of matter in fusion. ”

“ Our clothes are thus continually aerated by an exchange, the activity of which depends on the external temperature, the degree to which the atmosphere is agitated, and the porosity of the tissues; the essential point is that the change shall be so slow that the nerves of touch shall not be affected by it. The warmest coat is one of fur, and its warmth lies not in the skin only, but chiefly in the hairs, although their mass is relatively insignificant, and is almost wholly due to the air interposed between them. ”

“ A local accumulation of very dense rocks may increase the terrestrial attraction, and light ones may diminish it. The de-leveling of the ocean of which we have spoken, by which the waters near continents are elevated while the mass of the ocean at large is lowered, results in making an ocean-valley, as it were, from which the islands, that are thus nearer the earth's center than the continents, project. This will explain the increased rate of oscillation of the pendulum observed in many islands, which is otherwise inexplicable. ”

“ The form of the planets is itself an index, to a certain point, of the mode of their origin and their actual condition. These slightly flattened globes that wheel about the sun have been subject to the same laws that shape the drop of water and the grain of shot. ”

“ The activity of respiration and the consumption of oxygen are diminished during sleep, but increased in taking exercise, when a part of the heat produced is transformed into mechanical work; but, from birth to death, man continues, without ever wholly resting, to draw the breath that keeps up the fire of life.
Notwithstanding this incessant production of heat, which may be increased or diminished, according to circumstances, by as much as fifty per cent, the temperature of the body continues almost invariable. In health it is always about 98°, and seldom varies as much as 2° ”

“ Admitting that the temperature of the soil increases at the rate of 1° to 20 metres, we would reach at twelve kilometres a temperature of 600°; and at this depth the pressure of steam would equal the resistance. It would be necessary to go deeper if we adopt a less rapid rate of increase in temperature. Now, if water commences to boil beneath a certain level, the steam will rise through the mass and condense anew, as in a refrigerant imparting thereto a portion of its heat. The upper portion of the liquid will thus become heated more than the soil at the same level ”

“ An opinion or prejudice prevails widely that cotton is less healthful than linen, based on the fact that, being a less perfect conductor and rougher, cotton irritates the skin more than linen does. Examined with the microscope, the fibers of cotton appear angular and stiff, while those of linen are round and supple. Cotton is not agreeable in cutaneous affections, but wool, in such cases being more hairy and warmer, would be still more disagreeable. ”

“ If, in volcanic regions, the temperature is 1,000° at about twenty kilometres depth, the steam forming at that point may possess a pressure greater than 5,000 atmospheres—which would be sufficient to sustain the weight of a column of lava twenty kilometres high. At a temperature of 1,300° the pressure would doubtless be equal to 10,000 atmospheres. This is very nearly the force of the gas of gunpowder in a cannon of heavy caliber, and it is evident that this force would more than suffice for the mechanical effects of which volcanoes offer the terrifying spectacle. ”

“ If the earth were an exact sphere and entirely homogeneous, or if it were composed of homogeneous concentric spheres, the sun's attraction would have no effect on the movement of rotation; the axis of the earth would always remain parallel to itself—i. e., always point to the same place in the heavens; but the sun's action on the equatorial protuberance gradually effects a change of direction in the earth's axis, and the moon produces an analogous effect. ”

“ The vicinity of a mountain will deflect the plummet to a considerable degree, and a subterranean cavity may cause a deflection in the opposite way.
Let us now imagine the continents divided by a network of canals that connect all the seas, thus making of them one continuous sheet of water, as it were. Setting aside, for the purpose of the illustration, the oscillations caused by the tides, this sheet of water, assumed to be immovable, which represents the mean level of the sea, will exhibit elevations and depressions attributable to the local influences that deflect the plummet-line. ”

“ The heat of the bed thus favors the peripheric circulation and assists the internal organs that have to keep up the calorification. To do without a bed for several days in succession is a great privation, not only because it deprives the limbs of rest, but also because of the troubles to the economy it induces. A too hot and too soft bed is also objectionable because it keeps the body in a condition of moisture that enfeebles the muscular system and reduces all the functions. ”

“ Still, we can say that a great step has been taken toward the solution of the problem of life: the experiments of which this account is given have thrown light upon its approaches, and placed the question on the ground of exact science. No doubt a long time will pass before the progress of methods of observation shall permit us to make one step nearer to the goal, and nothing authorizes the belief that we can ever fully reach it ”

“ Thought, it is true, can transport us afar without taking note of distances, because there is no more difficulty in bringing up, in fancy, a remote object, than one that is close to us, and in this view it may be allowable to say that space creates no obstacle to thought—not impeding nor changing it in the least. ”

“ Applying this reasoning to the earth, we will assume that it is composed of a liquid mass covered by a solid pellicle. It is first of all evident that, if we set aside the perturbations caused by the equatorial enlargement, the entire mass will turn as one piece on its axis; if any difference whatever could exist between the rate of the envelope's rotation and that of the nucleus, friction will speedily annul it. The perturbing influence of precession and nutation imparts to the solid envelope's proper movement of rotation an extremely slight acceleration. ”