It may be remarked, says Mr. Parkes, that the Creator has endowed atmospheric air with the property of preserving its own equilibrium at all times and in all places. Its elasticity is such, that, however it may be consumed by respiration or combustion, its place is immediately supplied with a new portion; and though by a mistaken policy the doors and windows of our habitations may be constructed so as to exclude it as much as possible, it will have admission; it forces its way through every crevice, and performs the most important office assigned it, in defiance of all our exertions. If the properties which are given to the different substances in nature, and the laws by which they are governed, be thus examined, we shall find them all tending to promote the welfare and felicity of every species of animated beings.
The transparency of the air is a very beneficial property it possesses. According to Dr. Keill, and other writers on astronomy, it is entirely owing to the atmosphere that the heavens appear bright in the day-time. For, without an atmosphere, that part of the heavens only would shine in which the sun is placed: and if we could exist without air, and should turn our backs toward the sun, the whole heavens would appear as dark as in the night, and the stars would be seen as clear as in the nocturnal sky. In this case we should have no twilight; but a sudden transition from the brightest sunshine to the blackest darkness immediately after sunset; and from the blackest darkness to the brightest sunshine at sun-rising; which would be extremely inconvenient, if not fatal to the sight of men. But, by means of the atmosphere, we enjoy the sun’s light, reflected from the aërial particles, for some time before he rises, and after he sets. For, when the earth by its rotation has prevented us from seeing the sun, the atmosphere, being still higher than we, has the sun’s light imparted to it, which gradually decreases until he has descended 18 degrees below the horizon; and then, all that part of the atmosphere which is above us becomes dark. The atmosphere refracts the sun’s rays so, as to bring him in sight every clear day, before he rises in the horizon; and to keep him in view for some minutes after he is really set below it. For, at some times of the year, we see the sun ten minutes longer above the horizon, than he would be if there were no refractions; and about six minutes every day at a mean rate. We cannot but perceive the wisdom of God displayed in this contrivance, to prevent the sudden transition from light to extreme darkness, and his goodness manifested therein to man.
Besides these, there are many other advantages we derive from the atmosphere. Were it not for the atmospheric air, which is the vehicle of light and sound, our eyes would be useless, and the pleasures which arise from the variegated prospects that now surround us, unknown. Sound would never strike our ears, nor convey the charms of language from one person to another; all the delights of mutual converse would be lost. The sense of smell would never be regaled with odoriferous sweets; nor annoyed with exhalations from putrid and morbid substances. In short, life would become extinct, and a chaos of darkness and emptiness ensue. It has been well remarked, that, if the Deity had intended only to give us existence, and had been indifferent about our happiness or misery, all the necessary purposes of hearing might have been answered without harmony; of smell, without fragrance; of vision without beauty. The consideration of the various uses to which the different substances in nature may be applied, gives so satisfactory an assurance of the goodness of the Almighty, as is calculated to produce in us gratitude and obedience. With this view, an elegant French writer has said on this necessary fluid, “In the use of atmospheric air, man is the only being who gives to it all the modulations of which it is susceptible. With his voice alone, he imitates the hissing, the cries, and the melody of all animals; while he enjoys the gift of speech denied to every other. To the air he also communicates sensibility; he makes it sigh in the pipe, lament in the flute, threaten in the trumpet, and animates to the tone of his passions even the solid brass, the box tree, and the reed. Sometimes he makes it his slave: he forces it to grind, to bruise, and to move for his advantage an endless variety of machines. In a word, he harnesses it to his ear, and obliges it to waft him over the stormy billows of the ocean.”
Wind is air in motion. As the air is a fluid, its natural state is that of rest, which it cannot have but by an universal equilibrium of all its parts. When, therefore, this natural equipoise of the atmosphere is destroyed in any part, the circumjacent air necessarily moves towards that part, to restore it; and this motion of the air is called wind. Hence, where the equilibrium of the air is disturbed, the wind may blow from every point of the compass at the same time: those who live northward of that point have a north wind; those who live southward have a south wind; and so on of the rest: but those who live on the spot, where all those winds meet and rush together, will have turbulent and boisterous weather, such as whirlwinds and hurricanes, accompanied with rain, lightning, and thunder. For sulphureous exhalations from the south, torrents of nitre from the north, and aqueous vapors from every part, are there violently blended together, and seldom fail to produce these phenomena.
The causes of wind augment or diminish the gravity or elasticity of the atmosphere; for two portions of air, which are equal in elasticity or gravity, remain mutually immoveable. We must look for the causes of wind in the variation of heat and cold, the position of the sun, the nature of the soil, the inflammation of meteors, the condensation of the vapors into rain, and other similar circumstances: but the most general causes are heat and cold. Fire, which expands and rarefies the air, diminishes its elasticity, and, consequently, makes it lighter in some places than in others; hence the pressure of the ambient air is greater than that of the rarefied, whence a motion arises; and thus several winds blow towards the part where the air is rarefied by the heat; which currents of air, if strong, are called winds, if gentle, breezes or gales. Thus the air is constantly carried from the polar regions towards the torrid zone, where it is also affected by the diurnal motion of the sun from east to west.
“When we reflect attentively upon the nature of winds in general,” says Dr. O. Gregory, “considering all the causes which disturb the equilibrium of the atmosphere, the great mobility due to its fluidity and its elasticity, the influence of heat and cold upon the latter, the immense quantity of vapor with which it is charged and discharged alternately, the mutual effect of contiguous air and water in motion, the varied attractions of the sun and moon, upon the aërial fluid, and finally the changes produced by the earth’s rotation in the velocity of the atmospherical moleculæ at different parallels of latitude; we shall no longer be astonished at the inconstancy and variety which infringe upon the regularity of some of our winds, nor of the extreme difficulty of reducing the whole to laws wearing the semblance of certainty.”[66]
There is a great variety of winds. The ancients observed only four, called venti cardinales, because they blow from the four cardinal points. Homer mentions no more than eurus, the east; notus, the south; zephyrus, the west; and boreas, the north wind.[67] In imitation of him, others do the same. Afterwards intermediate winds were added, first one, then two, between each of these. Most writers, make only eight winds, and Vitruvius[68] informs us that the Athenians built a marble tower in the form of an octagon with eight winds marked, every one on that side which faced it. The moderns make 32 winds, the four cardinal winds 90 degrees distant, and 28 collateral or intermediate, 11 degrees and 15 minutes distant from each other, of which those in the middle between two cardinals, are 45 degrees distant from each cardinal.[69] But some make as many points on the compass, and as many winds, as there are degrees on the horizon, namely, 360.
The winds for a considerable space north of the equator, about 30 degrees in the open sea, blow from the north-east, and as far south of the equator, from the south-east. These are called trade-winds, from their facilitating trading voyages. In the Indian ocean, from its particular situation, and that of the lands which surround it, from April or May, to October or November, the wind blows from south-east to north-west; and during the rest of the year from the opposite quarters: these winds are called monsoons. In Jamaica and the Caribbee islands, in the months of July, August, or September, there are usually violent storms of wind, called hurricanes; the wind during the hurricane frequently veering, and blowing in every direction.
“Winds from all quarters agitate the air
And fit the limpid element for use,