A Comparative View of the Mortality of the Human Species, at All Ages. Black William
of the earth; and the distance of each from the equator is 90 degrees.
The earth has several incessant motions: one in which it turns, like a suspended wheel upon its own axis, from west to east, every twenty-four hours, which is the length of its day and night: the second, where it is rolling progressively in its great annual circle, or journey round the Sun: the third, the alternate inclination of its poles towards the sun at different times of the year: the fourth, the small circle which it describes monthly round the common center of gravity, or balance, with its moon. The earth’s diurnal revolution upon its axis, is at the rate of fifteen degrees, or 1,035 miles hourly. But the rapidity with which it is whirled in its annual orbit, is, hourly, 68,243 miles: whereas the swiftness of a ball discharged from a cannon is, in the same time, only 480 miles. Projected through the vacuity of heaven with this amazing velocity, in the space of 365 days, 5 hours, and 49 minutes, the earth completes its annual circle; which is the length of our year. The earth’s rotation every twenty-four hours upon its axis, is the cause of day and night, or of light and darkness. In this successive rotation, one half of its globular surface is always enlightened; the other half being then obscured in nocturnal gloom, except when enlivened by the reflected rays of the moon, or of one of the planets, or by the fainter glimmering of the fixed stars. The alternate spiral inflection and declination of the earth’s poles during its annual journey round the Sun, is the cause of the different lengths of Days and Nights; of the Seasons; of Summer and Winter; of the Equinoxes, and Solstices: and as each pole inclines or recedes, it is summer and winter, alternately, in their respective hemispheres. The effects of this compound terrestrial circumvolution on the animal and vegetable creation, would alone be a magnificent theme for many volumes.
One Moon only is allotted to our earth; from which it is distant 240,000 miles. The moon’s diameter is nearly one fourth less than that of the earth, which it obsequiously accompanies throughout its annual circuit; and round which it makes a perpetual revolution, from west to east, every lunar month. The constant agitation and periodical surges of the ocean, are greatly influenced by the moon, assisted, however, by the centrifugal force of the earth’s motion. It is also ascertained, that in some diseases, the human body is considerably under the lunar influence; and its energy is still more conspicuous at periodical changes, during the month and the year. Many arguments might be suggested to invalidate and overturn the ancient astrological systems, and to prove that the celestial influences upon us are not, in any considerable degree, derived from sources more remote than the solar confines.
The first Element in pre-eminence and subtility, without which all would be lifeless chaos in our system, is Heat and Light. Cold is a negative quality, and merely a comparative diminution of heat. The middle regions of the earth being repeatedly more exposed to the Sun’s vertical rays, are consequently most heated and scorched. From the equator to the poles, are all the gradations of heat and cold; but for reasons too prolix to enumerate, these gradations are not in exact measurement with the geographical distances from the equator; neither in the same continent, nor in different continents. By the scale of Farenheit’s thermometer, water boils at 212, freezes at 32; and blood-heat, or that of the human body, is about 97. The most intense heat of the tropical regions, as measured by the same thermometer, is frequently many degrees above the human temperature; and the most intense cold of the polar regions, often many degrees below 1 or 0 of the same scale. Neither of these noxious extremes of pestilential heat, nor of deadning blasts from boreal snow, could be long endured by the human species, were their bodies not protected and skreened by fences of nature or of art. Atmospheric heat, equal even to that of the human body, is felt intolerably scorching and suffocating. Every one also knows, by personal experience, that in different latitudes, and in summer and winter, the degrees of heat and cold, the duration, recurrence, and changes, are extremely variable. But within the equatorial limits, these variations are much less conspicuous, both in the thermometer and barometer. From this main spring and soul of animated nature, blessings and bounties are diffused, in thousands of channels, to every order of the creation; and from its extremes and vicissitudes, a multitude of evils and diseases are inflicted upon man.
Between the earth and celestial vacuum is interposed an element, called the Atmosphere, or Air. This invisible elastic fluid is floating equally round our planet, to the distance of at least forty-five miles perpendicular elevation. It has been compared by some philosophers, to packs of wool heaped on each other: that nearest the ground is most dense, compact, and ponderous; and as we ascend, it becomes gradually more rare, light, and cold. The prodigious gravity, or pressure, of this atmospherick column, appears incredible to those who are ignorant of experimental philosophy, and of the air-pump and barometer. Upon a man’s body, of middle stature, its weight is equal to thirty-two or thirty-three thousand pounds: but in rainy and variable weather, and especially on the summit of high mountains, there is a diminution in its pressure of many thousand pounds. This great mass of air, as well as the waters of the ocean and of rivers, is in constant agitation; sometimes gliding in gentle calms; sometimes, with wild uproar, raging in storms and hurricanes, and dispersed in a variety of currents, over different parts of the earth and ocean in Winds, constant, periodical, variable, and irregular. Without the concurrent support of air, animal and vegetable life would soon be annihilated. On them great and sensible effects are produced by the atmosphere and winds: by the air’s noxious impregnation, stagnation, want of elasticity, heat, cold, moisture, dryness; by the points from whence winds blow, their constancy, irregularity, recurrence, velocity.
The earth is the cistern, and one principal fountain of another still grosser element. From the Sun’s heat, and from the successive streams of air and winds, a prodigious evaporation is carried on from the surface of the ocean, from the land, and from vegetables. Whether part of the atmospherick air is also converted into vapour, is a question too intricate and diffuse for our present inquiry. The critical analysis and history of a single element, would alone far exceed the limits of this Dissertation. It is sufficient for us to observe, that these vapours, terrestrial and aerial, are collected into clouds, condensed, and again discharged upon the earth in Dews, Mists, Fogs, Rains, Snow, and Hail. The precipitation likewise of this accumulated vapour upon different parts of the globe, is periodical, regular, and variable. In quantity, duration, recurrence, and extent, these aqueous modifications are greatly diversified by the climate and soil, the vicinity to mountains and sea-coasts; the points from whence winds blow; and by many other causes, of which a detail cannot be here expected. From this source also ensue salutary and baneful effects, innumerable to animal and vegetable life.
Another subtile and active agent in the secret machinery of nature, is the Electrical Emanation; which, somewhat perhaps analogous to the aqueous evaporation and congestion before mentioned, is collected into clouds, and, with loud explosion, again discharged and dispersed into the air and earth: the fabulous thunderbolts and artillery of Omnipotence.
We now alight upon that solid mass, Earth, the most fixed and substantial of all the elements. The surface of our planet is composed of dry land and water; of which the ocean, without including lakes and rivers, occupies by much the largest extent. But the partition of the dry land into four continents, Europe, Asia, Africa, and America, is not well founded. Nature has in reality formed only three great insulated continents, exclusive of the smaller islands. Europe and Asia are contiguous, and cemented together as England and Scotland; or as France and Germany; and their boundaries artificial: whereas Africa, except the slender neck of land near Alexandria, is surrounded by sea. Of these four continents, Europe is the most diminutive. Asia and America stand dignified, above all the others, in superior magnitude. The dry land in Europe, Asia, and America, stretches to a great northern latitude, considerably within the arctick, or polar circles; and, spreading also in that part to a wide extent, east and west, forms nearly a complete bridge between Asia and America. Within the tropical circles are included the belly and bulge of Africa, and of South America, with a considerable portion of the broken southern extremities of Asia; together with most of the principal islands in the Pacific and Atlantic oceans. In all the hemisphere south of Capricorn, the land is greatly disproportioned to the ocean. The conical south point of America is but 55, and that of Africa only 35 degrees distant from the equator. A vast orbicular segment of this extreme of our planet, furnishes habitation for fishes only. The dry land is also diversified