« AnteriorContinuar »
ON ELECTRICITY, LOOMING, AND SOUNDS: TOGETHER WITH A TIEORY or THUNDER
SHOWERS, AND OF WEST AND NORTH-WEST WINDS.
BY GEORGE 1. HOPKINS, ESQ.
It is observable in almost every operation of nature, that all fluids possess strong aggregating properties; or in other words, powerful propensities to accumulate in large masses or bodies. This fact is so familiar in the element of water, as well as in the extensive collections of vapor, which are soon embodied into clouds, that it is only necessary to make a mere allusion to them. That the same principle governs in relation to the element of electricity or fire, I presume to be no less true. The nature and properties of the sun itself, so far as they are understood, may be deemed conclusive on this point. This mighty object, the instrument of light and life, is evidently an aggregation of all the vital principle of heat that belongs to our system; though it is now well understood, that this 'ocean of flame' is not a mere collection of fire, as has been supposed, but is connected with inconceivably large masses of materials of a very solid nature. From this vast mass, most copious streams are incessantly poured upon the planets. This is well known to he indispensable to the very existence of animal and vegetable life. Perhaps, too, it is as much a primary law in the government and movements of the planets themselves, as in the propagation and preservation of animal and vegetable existence. Without the constant exercise of this most potent agency, the earth could neither be clothed with verdure, nor could there be support for the nameless tribes of living beings that inhabit it.
As we approach the summer solstice, we find the earth profusely charged with heat; but it becomes much more intense afterward, in consequence of the great increase. To counteract an influence so universally predominant and strong that, were it to continue, would soon prove overwhelming, some energetic reacting principle or agent in the system was required, in order to produce a salutary corrective : for it was both a wise and an indispensable provision in nature, to ordain a permanent law that should afford the requisite relief from its enervating and pernicious pressure. Without the help of some active principle of this kind, it were scarcely necessary to say, there could be no duration of life or health. Animal and vegetable existence would soon be extinguished. Every thing, in short, would perish; and in place of that splendor and beauty which
every where present themselves to the enchanted eye, the face of creation would be parched, withered, and consumed.
That incomprehensible wisdom which guides and balances creation, of which we are destined to know nothing but from its effects, leaves no part of its works imperfect or unfinished. The same creative power has therefore ordained, that the superabundance of that element which, without some different disposition, would lead to the annihilation of all life, and of every vegetative germ, shall be made the great means of preserving both. And the more we enter into an examination of those laws and operations of nature which appear so wonderful, and which in many parts are so inscrutable, the more are we astonished and charmed in contemplating their well adjusted harmony and surprising beauty,
That the immense portion of heat which pervades the earth in the warm season is, from its inherent properties, constantly aggregating in numberless masses of various dimensions, there does not remain in my mind the smallest doubt. And what else is the electricity that is produced by art, and made to issue from a machine, but a simple collection or multiplication of that sustaining or animating principle, drawn suddenly io a point by some strong attractive property?
To this inherent principle alone, I conceive, may be traced the origin and existence of those bodies of unusual heat, of which Mr. Jefferson, in his celebrated Notes on Virginia,* makes mention, and which are so frequently felt by curious observers in the summer months. That enlightened philosopher did not attempt to explain either the cause of their formation, or what he supposed to be their ultimate end and use. I propose, but with all becoming deference, to offer my opinions in relation to both. And since nothing is known to exist that does not bear the impress of unequivocal design, and with a manifest tendency to usefulness, it cannot be deemed an irrational speculation to trace to some important end, the origin, design, and purpose
of their formation. I have witnessed these warm moving bodies in almost numberless instances. They were familiar to me in my early life, my residence then being near the foot of a ridge of very considerable elevation in the eastern part of Dutchess county; and the supposition follows that they are familiar to many others. At the same time, I am led to believe, that those who reside in elevated situations, have few opportunities of meeting with them; while those who are much employed in smooth grounds in a valley, will often remark them. For this, I think a very satisfactory reason may be given. Their specific gravity must necessarily carry them to the lower grounds, even supposing some of them to have been formed in higher parts ; though I think it very doubtful if any are produced in such places. I suppose the fact to be, that aggregation takes place more easily and more rapidly in an open country, or at the foot of high hills, where the land is level and well cleared, owing to the increased quantity of heat that is presumed to be deposited there, and the greater equality of the ground. Experience sufficiently shows, that an intense degree of heat will prevail in a valley, or over a plain, when the tops of high ridges are found to be comparatively cool.
*'Going out into the open air, in the temperate and in the warm months of the year, we often meet with bodies of warm air, which, passing by us in two or three seconds, do not afford time to the most sensible thermometer to seize their temperature. Judging from my feelings only, I think they approach the ordinary heat of the human body. Some of them perhaps go a little beyond it. They are of about twenty or thirty feet diameter horizontally. Of their height we bave no experience, but probably they are globular volumes, wasted or rolled along by the wind. But whence taken, where formed, or how generated ? They are not to be ascribed to volcanoes, because we have none. They do not happen in the winter, when the farmers kindle large fires in clearing up their grounds. They are not confined to the spring season, when we have fires which traverse whole counties, consuming the leaves which have fallen from the trees. And they are too frequent and general to be ascribed to accidental fires. I am persuaded their cause must be sought for in the atmosphere itself; to aid us in which, I know but of these constant circumstances; a dry air, a temperature as warm at least as that of the spring or autumn; and a moderate wind. They are most frequent about sunset; rare in the middle part of the day; and I do not recollect ever having met with them in the morning.'
Notes on Virginia.
of the truth of the fact that these mysterious bodies are mostly formed in low grounds, I feel thoroughly persuaded ; for as often as I have ascended the side of the ridge just mentioned, which was in almost numberless instances after the sun had disappeared, I have no recollection that I ever came in contact with one of them. They are most commonly felt in a warm evening after a sultry day, about sunset, as Mr. Jefferson states, or soon after, and invariably when the wind is from the south or south-west. The power of the sun being then withdrawn, and the air being somewhat cooled, these warm moving bodies make a more sensible impression upon the observer when he meets with them. I have sometimes encountered several in the course of an afternoon and early in the evening; but more frequently in a meadow than in any other place. They appear to me to be infallible precursors of a thunder-storm, which usually happens on the succeeding afternoon or evening.
From the frequency of these bodies, during the most oppressive part of the summer, (and I believe they are seldom met with in any other season,) I am led to believe, that if a line of men were placed across a piece of low and level ground, for the extent of a quarter or half a mile, supposing it to have a north and south direction, with instructions to notice the state of the atmosphere, imagining a gentle current of air from the south, they would find them very numerous. It is not to be supposed they are all of equal magnitude; I presume they are of various sizes; though it has always appeared to me, that those which seemed largest, seemed also to contain the highest portion of heat. Not only do I feel well persuaded of this fact, but I think the conclusion warranted from the nature and properties of the bodies themselves. I deem it proper to remark in this place, as it goes
mind to corroborate the hypothesis I have assumed, and at the same time is in itself a circumstance not a little remarkable, that I have never in the course of my life met with one of these warm bodies either immediately succeeding a thunder-storm, or yet for some time afterward. The plain reason I suppose to be this : they have been removed by the combined operation of the elements; and in their removal, a law is fulfilled that is not only indispensable in the economy of nature, but in the highest degree beneficial in many of her movements. The atmosphere is then no longer charged with a burdensome portion of heat, but from the fierce concussions that have