A Comparative View of the Mortality of the Human Species, at All Ages. Black William
A
Comparative View, &c.
INTRODUCTION.
A Sketch of our Planet’s Station, Rotation, and Rank amongst the other Celestial Orbs; and of its Investing Elements:—of the Habitable Parts of our Planet: the Number of the Human Species, and their Division into various Classes, Genera, Groups, and Gradations: their Comparative Births.
There are two methods of promoting Medical Knowledge: one by negative information, or criticisms on the numerous errors of preceding authors: the other by direct instruction, and improvement on former models. The first method is worn out in hackneyed chimes: the second is encumbered with infinitely more difficulties; and its merits paramount in the superlative degree. However unequal I have imposed upon myself the latter task. But, previous to the discussion of the general theme, it will conduce to order, and to the anticipation of explanatory digression and illustration, to glance at the station, rotation, and rank of our Parent Planet amongst the other celestial orbs; at its investing elements; and at the number, groups, and recruit of mankind. A navigator or historian, who undertakes the description of any island, kingdom, or continent, commences with their geographical outlines and climate, penetrating afterwards thorough a scrutiny of the inhabitants. Upon a similar, but more majestic model, our Introductory Preface is founded. Throughout the whole of this intricate, sublime, and inexhaustible subject, if I do not delay sufficient time to fix, I shall at least hope to start the reader’s attention to a variety of grand objects, inseparable from a comprehensive knowledge of Medicine; and of which I shall touch the fundamental keys and chords.
The Solar System
consists of the Sun, of seven Planets surrounded by ten or more Moons, and of the Comets. The other siderial lights with which the vault of Heaven is studded, and which are denominated Fixed Stars, have a very distant affinity with our planetary sphere: they are infinitely too remote to be enlightened by our luminary; and therefore astronomers, with good reason, imagine each star to be a sun to encircling planets, though invisible to us; and to constitute throughout boundless space thousands, or perhaps millions, of habitable worlds. Numbers of those stars, most luminous and proximate, are arranged into arbitrary clusters, called Constellations, or Signs; and serve to mark the several stages of the rotating orbs in our system.
The Sun, whose magnitude far surpasses that of the seven planets united, is placed in the center, suspended in the immense celestial expansion and firmament. Surrounding him, at different distances, and in the following order, are the planets Mercury, Venus, the Earth, Mars, Jupiter, Saturn, Georgium Sidus. These planets are incessantly revolving from west-by-south to east, and within certain intervals of time, make a complete circle round the Sun; which is the length of each planet’s year; and is larger and longer in proportion to their respective distances. The velocity of their revolution in their annual orbits, together with their gradations of light and heat, are also in proportion to their solar proximity. From the Sun, the Planets, with their surrounding moons, derive heat and light; and when this is intercepted by any planet, or its satellite, an eclipse or darkness ensues. In what periods those tremendous celestial bodies, named Comets, revolve round the Sun, is not yet exactly adjusted.
One of the seven planets, the Earth, this small domain of restless mortals, and to which all our future observations shall be directed, is distant from the Sun 95,173,000 miles. In shape, it has more resemblance to a turnip than to a globe. Its diameter is 7,970 miles: its circumference 360 degrees; which amounts to 24,840 English miles. Geographers divide the globe of our planet into two equal parts, or hemispheres, the northern and southern, by an imaginary girdle, or ring, named the Equator. Two other imaginary girdles surrounding the earth, and distant from the equator on each side 23½ degrees, north and south latitude, are named the Tropicks of Cancer and Capricorn; comprehending between them the torrid zone. From these tropical circles the zones, called Temperate, extend on each side 43 degrees: and at their extreme boundaries, we reach the polar circles 23½ degrees distant from each pole. The north and the south poles are in the