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beauties of nature visible throughout the poem. In an old writer it would be accounted a gem.
6.-Essays on Meteorology. By JAMES P. ESPY, Member of the American Philosophical Society, &c. &c. From the Journal of the Franklin Institute. Vol. xvii.
WE are induced to give the following outline of these Essays, by the fact that the Legislature of Pennsylvania have recently voted a handsome appropriation, to enable Mr. Espy to continue and perfect his experiments in Meteorology. We presume we shall gratify general readers by placing the substance of these papers before them.
In these essays Mr. Espy, proposes, and illustrates a new "Theory of Rain, Hail, and Snow, Water-spouts, Land-spouts, Variable Winds, and Barometric fluctuations:" and we are sure of bestowing a merited encomium, when we pronounce the essays above mentioned as characterized at once by modesty, simplicity, ability and truth.
Up to this time, the only plausible account which has ever been given of the production of rain, is that proposed by Dr. Hutton, and since adopted and generalized by subsequent philosophers-the substance of which is this. The process of evaporation being constantly going on, watery vapor is continually accumulating in the atmosphere, and owing to the variable action of the causes producing evaporation, more vapor will pass into the atmosphere in some districts than in others. The subtle and ever restless agency of heat, which is unceasingly modifying the density of the atmosphere, by its unequal action, disturbs the atmospherical equilibrium, and winds are occasioned; currents of different temperatures are mingled, the mixture
at the temperature which it assumes, is not capable of retaining all the moisture of the two currents, and a portion is deposited in the form of rain. Such is the outline of Hutton's theory of rain. It is founded upon the fact which experiment has established, that the capacity of air to retain moisture, increases more rapidly than the temperature does: for instance, air at 60° Fahrenheit's thermometer is capable of holding in suspension a certain quantity of vapor-air at 90°, will hold more than half as much additional vapor, and air at 120°, will hold more than twice as much. Suppose therefore two currents of air to meet, one of them being at the temperature 60°, the other at 90°, and each current to be charged with its maximum of watery vapor. After mingling, the resulting temperature must, according to established laws, be 75°; but according to what we have said, the current at 90°, holds more vapor in proportion to its temperature, than that at 60° does in proportion to its temperature-when therefore the air at 60° is raised to 75°, it can take up some of the vapor which cannot now be retained by that which is reduced from 90° to 75°; but it cannot take up all, and this excess is what is deposited in the form of rain. Such is the theory which has prevailed since Dr. Hutton proposed it. The recent one of Mr. Espy is essentially different, and in our opinion much more simple, much more general, much less liable to objections, and much more decidedly confirmed by observed phenomena.
This theory is founded, first upon the result of some highly approved experiments of M. M. Berard and De la Roche, fixing the specific heat of atmospheric air at 250, that of water being 1. Secondly, upon the celebrated discoveries of Dr. Black, concerning latent heat, and thirdly upon the admirable results developed by Dr. Wells, in his Essay on Dew. Each of these three classes of results has stood the test of the closest scrutiny, by men most competent to judge of their correctness. They are admitted by all philosophers to be mainly true, and the strictly legitimate application which Mr. Espy has made of them in his "theory of rain &c.," is both sagacious and simple.
We proceed to let Mr. Espy speak for himself, in explanation of his theory:
"It has been shown by the experiments of Berard and De la Roche, and also by those of Clement and Desormes, that the specific heat of atmospheric air is about .250, that of water being 1.
"Now, if these experiments be correct, and they appear to be so, it will be easy to account for the formation of rain, snow, and hail, and several other atmospheric phenomena, which have never yet been satisfactorily explained.
The theory of these meteors may be given in a few words. When a portion of transparent vapor, in the air, is condensed into cloud, or water, the latent caloric given out expands the air containing it, six times as much as it contracts by the condensation of the vapor into water."
This position is shown by Mr. Espy, by a simple calculation founded on acknowledged data-he then proceeds:
"It follows, then, from the principle here demonstrated, that the moment a portion of the transparent vapor in the air begins to condense into cloud, the
VOL. I.-NO. I.
air in which it is begins to expand, and, consequently, if an equilibrium existed before, it is now destroyed, and the cloud will continue to ascend as long as its temperature is greater than that of the surrounding air."
We ornit some remarks, and calculations, elucidating the change of the dew-point, and of the temperature of the cloud in its ascent:
"Thus it appears, that the temperature of air when it has ascended 6000 yards with a dew-point of 71° at its commencement, will have a dew-point of 34 degrees, and be 23° warmer than the surrounding air at that elevation. In like manner it may be shown, by assuming other points at greater elevation in this upward motion, that the difference of temperature between the air in the vortex, and the surrounding air, is constantly increasing with the elevation, until the moment when the vapor is all condensed into water, when it will be 71. 2o higher. After it passes this point, it will continue its motion upwards, dry, and of course, not increasing in temperature beyond 71.2° higher than the surrounding air, but will preserve this difference, until it reaches the surface of the atmosphere, where it will spread itself out and come to rest. We have now a column of air reaching from the surface of the earth to the surface of the atmosphere, of the same temperature as the surrounding air below, and 71. 2° greater above, making a mean of 35. 6°."
From these data, and assuming the mean temperature of the whole atmosphere to be 320, which is certainly high enough, Mr. E. arrives at the conclusion that the air within the vortex is pressed upward with a force capable of imparting to it a velocity of 364 feet per second, equivalent to about 4 miles per minute, or 318 miles per hour.
"Nor" says he "is this great velocity at all incredible, for the upward motion in the vortex, is as much greater, than the horizontal motion of the air towards the vortex, as the motion of the air in a chimney is greater than the horizontal motion of the air in the room toward the fire-place.'
The application of this theory to the phenomena of rain, hail, &c., is natural and simple-the vapor in the vortex is condensed into rain, this is still carried up by the great upward force of the vortex, it reaches the region of perpetual congelation, is congealed into hailand in that form is forced up, until it reaches that point where the ascending current spreads itself out on the subambient atmosphere, then-the hail, no longer sustained by a force pressing upward-begins to fall, as it descends, passing through warmer regions of the air, it may be entirely or only in part melted into rain again-under some circumstances producing only rain, and, under different circumstances, producing a mixed storm of rain and hail.
Mr. Espy has very ingeniously applied his theory to the explication of several remarkable storms of rain and hail, on record in the annals of meteorology; and he has also, satisfactorily to us, explained by his theory the formation of water-spouts, and land-spouts, and their kindred phenomena.
Three reports have been made upon the subjects of Mr. Espy's essays, by a joint committee of the American Philosophical Society, and of the Franklin Institute of the State of Pennsylvania, for the promotion of the mechanic arts. And they all go to confirm the above noticed theory, by a careful analysis of the facts relating to a number of storms recently observed in the United States. The whole subject is cordially recommended to the examination of the scientific and
curious-as not only highly interesting in itself, but as also capable of being turned to the most useful account.
Mr. Espy himself says of the law which he has developed, that its "importance will readily be admitted, when it is understood that by it may be known, whether there is a great storm raging at any time within four or five hundred miles of the observer, and also the direction of that storm, with the means of avoiding it, if the observer is at sea." But, in order that this desirable result may be attained, observations must be made throughout great extents of country, on all the circumstances of storms. From such observations, it is believed that tables may be formed, by which the existence, remoteness, direction, &c., of a storm may be discovered by a distant observer. And surely no man who has seen-what they who "go down to the sea in ships, and do business on the great waters" so often see-the roaring winds, and the raging ocean, those "wonders" which the Lord "doeth in the deep," who on the billows hath been "carried up to the heaven, and down again to the deep," who hath there seen the "souls of men melting within them," and heard the deep and solemn prayer, "Thou, O Lord, who stillest the raging of the sea, hear, hear us, and save us that we perish not"'--no man who hath seen this, can regard, without interest, any rational efforts for diminishing "the perils of the deep;" nor can any man who sympathizes in the sufferings, or rejoices in the welfare of his species, contemplate with indif ference so valuable a desideratum.
Boston: W. S.
7. Three Experiments of Living: Living within the means.
THIS is a good little book; it is peculiarly appropriate in these times of show and extravagance, when so many are "living beyond the means," to gain, what they call, a standing in society. prises," as the editor tells us, "in the form of an interesting narrative, a practical display of important maxims in domestic economy and the conduct of life-the advantages of living within one's means, on the one hand, and, on the other, the misery and wretchedness attendant upon an opposite course; not merely as regards the physical comforts of the unhappy individual, who is the subject of it, but his moral condition." We think, that this little book is calculated to exert an influence on the mass of men, which would be denied to larger, and more pretending volumes.
It is the history of Dr. and Mrs. Fulton. With nothing to depend on but his profession, they commence life, boarding in an humble way, rich only in peace and contentment, until the increase of his business
enabled them to take a small house. The descriptions of their evening conversations, when he had returned from his visits, and coveting nothing in the world around them, they were left to the enjoyment of each other's society, are beautiful:
"When her children were fairly in bed, and the domestic duties of the day over-when her husband laid aside his day-book and ledger-when the fire burnt bright, and her little work-table stood by her side-when Frank ventured to pull off his boots, and lay half-reclined on the sofa, then came the hour of conversation. Then Jane loved to talk over the past and the present, and sum up their stores of happiness. Sometimes she requested her husband to read aloud; but he never got through a page, without her interrupting him, to point out something congenial, or something in contrast with their situation; and the book was soon thrown aside, as far less interesting than their own conversation.
"I do positively believe,' said Jane, we are the happiest people in the world. I can say, with truth, I have scarcely a wish ungratified." I am sure I envy nobody.'
This was the first stage, "living within the means;" when the end of every year left them a small overplus; and it was the most happy period of their lives. It was one of honest independence. "Their pleasures were home pleasures-the purest and most satisfactory that this world affords."
But these bright days were soon to pass away. A larger house having become necessary, one was taken in a more fashionable part of the town. Unfortunately, their next door neighbors were the Reeds, "a stylish family," who began to initiate Mrs. Fulton into all those artificial wants, of which she had never before dreamed. Then the enemy was sowing tares; and pride and ambition were springing up in her simple and peaceful heart. She soon became a fashionably dressed lady. Then came the agony of keeping up a showy appearance, when they could ill afford it-the first symptoms of domestic discord in those, who had before been every thing to each other-and the constantly accumulating expenses. Well would it have been for them, had they taken the advice of their uncle Joshua, whose plain, honest, and upright character, forms, through the whole volume, a strong contrast to the hollow-heartedness of her new and fashionable friends. "It is very well," said he "for people to live in what is called style, if they have all things in agreement; if they can afford to have the best of attendance, of cooks, &c. ; but there is no gentility in doing things by halves." This year, however, Dr. Fulton's expenses exactly met his income. He was "living up to the means."
We now come to the last scene, "living beyond the means.' A large house is procured, and furnished in a more costly manner. Mrs. F. has worked her way within the magic circle of fashion, and is every where a welcome visiter. But is she more happy? How can she be, when she is vainly seeking in society, that peace which she once had by her own fireside-in the company of her husband and children? But those days have gone. She has become aspiring and hollow-hearted. Ambition and gaiety have also estranged her hus. band, until she is forced sometimes to say to herself" How Frank has