Chapter IV: Third Day (1)

_Section_ I.--THE SEA.

Water and land separated -- Formation of the sea -- Its
restrictions -- Extent -- Depth -- Composition -- Saltness
-- Motion -- Tides -- Four states of water -- Circulation --
Religious improvement.

On the _third day_, the earth was drained, and the waters, which before covered its surface, were gathered into copious receptacles, and called seas. God said, “Let the waters under the heaven be gathered into one place, and let the dry land appear; and it was so. And God called the dry land Earth; and the gathering together of the waters called he Seas.” The almighty Creator proceeds to separate, put in order, and control the element nearest to _light_ and _air_ in quality and use, and, although not elastic, yet of great power. Probably the air was used by him as the great agent in gathering the waters into one place. Thus, instead of the confusion, which existed when the earth and the water were mixed in one great mass, there is now order; and by their separation each is rendered useful: the earth affording a habitation and support for man and the various orders of land animals; and the water forming an abode for the numerous tribes of living creatures adapted to subsist in that liquid element.[74]

Previous to this arrangement, the water, being a pure element, was above the earth. Thus the Psalmist, “Thou coveredst it with the deep as with a garment: the waters stood above the mountains,” so that they did not appear. “At thy rebuke they fled; at the voice of thy thunder they hasted away.” At the omnipotent word they started back, and shrunk away, says Bishop Patrick; like an affrighted slave at the thunder of his master’s threatenings, if his commands are not obeyed. They gathered themselves in those places where they now are, which by Moses are called seas; and there God shut them up, confining them that they might not return to cover the earth. God “brake up,” for the reception of the waters, his “decreed place,” that vast concave or hollow in the earth; “and set bars and doors,” banks and shores, the weak sand to control this element, which, however it roar and struggle, it cannot pass.

It is wonderful that the sea, which has a natural disposition, from its being a purer and lighter element, to be above the earth, should not overflow it; but the amazing power of Omnipotence retains it within its prescribed limits. For he has pronounced, “Hitherto shalt thou come, but no further; and here shall thy proud waves be stayed.” As if he had said, Though thy tides flow with mighty strength, though the swelling billows of thy pride (so the original) rise high in a storm, and dash against the shore with impetuous force and overwhelming rage, yet here shall they stop: though they roar and foam, as if irritated at the opposing strand, yet dare not to approach beyond those limits to thee assigned; but, obedient to thy Lord and Master, submissively retire. Here we see the power and dominion of the supreme Being in the kingdom of nature, whose sway the sea is subject to! Our preservation from its threatening destruction, by the continual restrictions it is under, is a perpetual expression of Divine goodness and mercy, and should induce all men to live always in the reverential fear of God. “Fear ye not me? saith the Lord: will ye not tremble at my presence, which have placed the sand for the bound of the sea, by a perpetual decree, that it cannot pass; and though the waters thereof toss themselves, yet they cannot pass over it.”

If we look upon the map of the world, we shall find that the ocean occupies a considerably greater surface of the globe than the land is found to do. Although the ocean, properly speaking, is but one extensive sheet of water, continued over every part of the globe without interruption; and although no part is divided from the rest, yet geographers have distinguished it by different names, as the Atlantic or Western Ocean; the Northern, Southern, Pacific, Indian, and German Oceans. In this vast receptacle, almost all the rivers of the earth ultimately terminate. And yet these vast and inexhaustable supplies do not seem to increase its stores; for it is neither apparently swelled by their tribute, nor diminished by their failure; it continues constantly the same. Indeed, the quantity of water of all the rivers and lakes in the world is nothing compared to that contained in this prodigious reservoir. And some natural philosophers have carried their ideas on this subject so far as to assert, in consequence of certain calculations, that, if the bed of the sea were empty, all the rivers of the world flowing into it with a continuance of their present stores, would take up at least 800 years to fill it again to its present height.[75]

To ascertain the _depth_ of the sea has been found impracticable, both on account of the numerous experiments which it would be found necessary to make, and the want of proper instruments for that purpose. Beyond a certain depth the sea has hitherto been found unfathomable; and though several methods have been contrived to obviate this difficulty, none of them has completely answered the purpose. We know in general that the depth of the sea increases gradually as we leave the shore; but if this continued beyond a certain distance, the depth in the middle of the ocean would be prodigious. Indeed, the numerous islands every where scattered in the sea demonstrate the contrary, by showing us that the bottom of the water is unequal like the land, and that so far from uniformly sinking, it sometimes rises into lofty mountains. If the depth of the sea be in proportion to the elevation of the land, as has been generally supposed, its greatest depth will not exceed five or six miles; for there is no mountain six miles perpendicular above the level of the sea. The sea has never been actually sounded to a greater depth than a mile and 66 feet; every thing beyond that, therefore, rests entirely upon conjecture and analogical reasoning, which, in this case, are in no wise conclusive. Along the coasts, where the depth of the sea is generally well known, it has always been found proportioned to the height of the shore; when the coast is high and mountainous, the sea that washes it is deep; when, on the contrary, the coast is low, the water is shallow. Whether this analogy holds at a distance from the shore, experiments alone can determine.

Water is an uninflammable fluid, says Dr. O. Gregory, and, when pure, is transparent, colorless, and void of taste and smell. Mr. Cavendish made a discovery that it is formed by the union of _hydrogen_ and _oxygen_. It may, therefore, be considered as _oxide of hydrogen_: oxygen and hydrogen appearing to unite, only in that certain proportion of which water is the result. In 1798, (observes Mr. Parkes) Mr. Sequin made a grand experiment for the composition of water. He expended no less than 25,582 cubic inches (or nearly two hogsheads) of inflammable air, and 12,457 of vital air. The first weighed 1,039 grains, and the second 6,210, amounting to 7,249 grains, and the water obtained amounted to 7,245 grains, or about three-fourths of a wine pint. The loss was only four grains. Another experiment was afterwards made by Le Fevre, in which nearly two pounds and a quarter of water was produced.

The sea water contains a quantity of _salt_, but not in the same proportions every where. In the torrid zone, where otherwise, from the excessive heat, it would be in danger of putrefaction, the water is found most salt; as we advance northward its briny quality diminishes, till at the poles it is nearly gone altogether. Under the line, Lucas found that the sea comprised a seventh part of solid contents, consisting chiefly of sea-salt. At Harwich, he found it yielded 1-25 of the same matter. At Carlscroon, in Sweden, it contains 1-30 part, and on the coast of Greenland a great deal less. This gradual diminution of saltness from the equator to the pole, is not, however, without particular exceptions. The Mediterranean sea contain 1-22 of the sea-salt, which is less than the German sea contains. The saltness of some seas, or of particular parts of the same seas, may be increased, as Mr. Boyle intimates, from rocks and other masses of salt, either at the bottom of the sea, or dispersed near their shores.

This phenomenon of the sea perplexed the philosophers before the time of Aristotle, and surpassed even the great genius of that philosopher. Father Kircher, after having consulted three and thirty authors upon the subject, could not help remarking, that the fluctuations of the ocean itself were scarcely more various than the opinions concerning the origin of its saline impregnation. Bernadine Gomesins, (observes Bishop Watson) about 200 years ago, published an ingenious treatise on salt: in this treatise, after reciting and refuting the opinions of Empedocles, Anaxagoras, and Aristotle, on the subject in question, he proposes his own; wherein he maintains, that the sea was originally created in the same state in which we at present find it, and impregnated, from the very first, with the salt which it contains. Indeed, we cannot account for the general saltness of the sea from second causes; hence we must suppose it has had this property from the creation. Naturalists assure us, that, though some few species of fishes thrive in fresh water, and some others live alternately in fresh and salt, yet by far the greatest number cannot exist out of the sea; which is a proof that the sea was at the creation impregnated with salt.

The saltness of the sea has been considered by some as a peculiar blessing from Providence, in order to keep so great an element pure and wholesome: but facts prove that this property is not capable of preserving it from putrefaction. Sir Robert Hawkins, one of our most enlightened navigators, gives an account of a calm, in which the sea continuing for some time without its usual motion, began to assume a very formidable appearance. “Were it not (says he) for the moving of the sea, by the force of winds, tides, and currents, it would corrupt all the world. The experiment of this I saw in the year 1590, lying with a fleet about the islands of Azores, almost six months; the greatest part of the which time we were becalmed. Upon which all the sea became so replenished with various sorts of gelies, and forms of serpents, adders, and snakes, as seemed wonderful; some green, some black, some yellow, some white, some of divers colors, and many of them had life; and some there were a yard and a half and two yards long; which had I not seen, I could hardly have believed. And hereof are witnesses all the companies of the ships which were then present; so that hardly a man could draw a bucket of water clear of some corruption. In which voyage, towards the end thereof, many of every ship fell sick, and began to die apace. But the speedy passage into our country was a remedy to the crazed, and a preservative for those that were not touched.”[76] Mr. Boyle informs us, that he once kept a quantity of sea water, taken from the English channel, for some time barrelled up; and, in a few weeks, it began to acquire a fetid smell. He was also assured by one of his acquaintance, who had been becalmed for about fourteen days in the Indian ocean, that the water, for want of motion, began to stink; and, that had the calm continued much longer, the stench would probably have poisoned him. It is the motion, therefore, and not the saltness of the sea, that preserves it in its present state of salubrity.[77]

The sea has three kinds of motion: the _first_ is that undulation which is occasioned by the wind. This motion is evidently confined to the surface; the bottom, even during the most violent storms, remains perfectly calm. Mr. Boyle has remarked, from the testimony of several divers, that the sea is affected by the winds to the depth only of six feet. It would follow from this, that the height of the waves above the surface does not exceed six feet; and that this holds, in the Mediterranean sea at least, we are informed by the Compte de Marsigli; though he also sometimes observed them, during a very violent tempest, rise two feet higher.

The _second_ kind of motion is that continual tendency which the whole water in the sea has towards the west. It is greater near the equator than about the poles; and, indeed, cannot be said to take place at all in the northern hemisphere beyond the tropic. It begins on the west side of America, where it is moderate; hence that part of the ocean has been called _Pacific_. As the waters advance westward, their motion is accelerated; so that, after having traversed the globe, they strike with great violence on the eastern shore of America. Being stopped by that continent, they turn northward, and run with considerable impetuosity in the Gulf of Mexico; from thence they proceed along the coast of North America, till they come to the south side of the great bank of Newfoundland, when they turn off, and run down to the Western Isles. This current is called the _Gulf stream_. It was first accurately described by Dr. Franklin, who remarked also, that the water in it having been originally heated in the torrid zone, cools so gradually in its passage northward, that even the latitude might be found in any part of the stream by means of a thermometer. This motion of the sea westward has never been explained: it seems to have some connection with the trade-winds, and the diurnal revolution of the earth upon its axis.

The _third_, and most remarkable motion of the sea, is the tide; which is a regular swell of the ocean every 12 hours, accounted for from the principal of gravitation. The sagacious Kepler long ago conjectured, that the earth and moon, and every particle of them, mutually gravitate towards each other, and are the cause of the tides. If, says he, the earth ceased to attract its waters towards itself, all the water in the ocean would rise and flow into the moon: the sphere of the moon’s attraction extends to our earth, and draws up the water. This, at that time, was mere conjecture; for Sir Isaac Newton was the first who clearly pointed out the cause of this phenomenon. On the shores of the ocean, and in bays, creeks, and harbors, which communicate freely with it, the waters rise above their mean height twice a day, and as often sink below it, forming what is called a _flood_ and an _ebb_, a _high_ and _low water_. It has been stated, that in the middle of the sea the tide seldom rises higher than one or two feet; but, on the coast, it frequently reaches to the height of 45 feet, and, in some places, even to more. At Plymouth, it is sometimes 21 feet between the greatest and least depth of the water in the same day, and sometimes only 12 feet.

When the sun and moon act conjointly on the tides, which is at the change and full of the moon, they are stronger and run higher than at other times, and are called _spring tides_; but when the sun and moon are 90 degrees apart, their attractive powers, being in opposition to each other, occasion the tides to be weaker and lower than at other times, and these are called _neap tides_. The word _neap_ is derived from the Saxon; it signifies low, decrescent, and is used only of the tide. These different heights of tide are observed to succeed each other in a regular series, diminishing from the greatest to the least, and then increasing from the least to the greatest, according to the age and situation of the moon.

“The moon turns ocean in his bed,
From side to side, in constant ebb and flow,
And purifies from stench his watery realms.”

Sir Isaac Newton calculated the attractive powers of the sun and moon on the tides, and found the attraction of the latter to be about three times greater than that of the former.

Water is found to exist in four states: namely, solid, or ice; liquid, or water; vapor, or steam; and in a state of composition in other bodies. The younger Lemery observes, that ice is only the re-establishment of the parts of water in their natural state; that the mere absence of fire is sufficient to account for this re-establishment; and that the fluidity of water is a real fusion, like metals exposed to the fire; differing only in this, that a greater quantity of fire is necessary to the one than the other.

Underneath the poles, water is always solid; there it is similar to the hardest rocks, and may be formed by the chisel of the statuary like a stone. The following circumstance, noticed by Bishop Watson, will show the solidity that water is capable of acquiring when divested of a large portion of caloric. It is related that at the whimsical marriage of Prince Gallitzen, in 1739, the Russians applied ice to the same purposes as stone. A house, consisting of two apartments, was built with large blocks of ice; and the icy cannon, which were fired in honor of the day, performed their office more than once without bursting.

During the severe winter of 1740, observes M. de Bomare, a palace of ice, 52 feet long, 16 wide, and 20 high, was built at Petersburgh, according to the most elegant rules of art. The river Neva afforded the ice, which was from two to three feet thick, blocks of which were cut and embellished with various ornaments. When built up, the different parts were colored by sprinkling them over with water of various tints. Six cannons, made of and mounted with ice, with wheels of the same matter, were placed before the palace; and a hempen bullet was driven by one of these cannons, in the presence of the whole court, through a board two inches thick, at the distance of sixty paces. Cowper remarks,--

“No forest fell,
Imperial mistress of the fur-clad Russ,
When thou wouldst build--no quarry sent its stores
T’ enrich thy walls; but thou didst hew the floods,
And make thy marble of the glassy wave.
Silently as a dream the fabric rose,
Ice upon ice; the well-adjusted parts
Were soon conjoin’d; nor other cement ask’d
Than water interfused to make them one.
Lamps gracefully disposed, and of all hues,
Illumin’d ev’ry side. Long wavy wreaths
Of flowers, that feared no enemy but warmth,
Blush’d on the pannels, which were once a stream,
And soon to slide into a stream again.”

In the most northern part of the Russian territory, the cold is sometimes sufficient to freeze mercury, or 72 degrees below the freezing point of water.[78] It is so intense in some seasons, that the poor inhabitants cannot venture out of their miserable huts but at the hazard of their lives.

“There, through the prison of unbounded wilds,
Barr’d by the hand of nature from escape,
Wide roams the Russian exile. Nought around
Strikes his sad eye but deserts lost in snow,
And heavy loaded groves, and solid floods,
That stretch athwart the solitary vast
Their icy horrors to the frozen main.”

In Iceland and Germany the thermometer frequently falls to zero, which is 32 degrees below the freezing point. At Hudson’s Bay it has been known to sink even 50 degrees lower. When stones or metals, which have been exposed to such degrees of cold, are touched by the tongue, or the softer parts of the human body, they absorb the heat from those parts with such rapidity, that the flesh becomes instantly frozen and mortified, and the principle of life in them is extinguished. Some French academicians, who made a journey to the northern end of the Baltic, and wintered under the polar circle, found it necessary to use all possible precautions to secure themselves from the dreadful cold which prevailed. They prevented, as much as possible, the entrance of the external air into their apartments; and if at any time they had occasion to open a window or a door, the humidity of their breath, confined in the air of the house, was condensed and frozen into a shower of snow; their lungs, when they ventured to breathe the cold air, felt as if they were torn asunder; and they often heard the rending of the timber around them by the expansive power of the frost on the fluid in its pores. In this terrible cold the thermometer fell to 33 below zero.[79] The most intense cold ever known in the neighborhood of London was on December 25th, 1796, when the thermometer indicated 2 below zero.

The ice at each pole of the earth forms an immense cupola, the arch of which extends some thousand miles over the continents; the thickness of which, beyond the 60th degree of latitude, is several hundred feet. Navigators have assigned to detached masses, which are met with floating at sea, an elevation of from 1,500 to 1,800 feet.[80] There can be no doubt but that the thickness of these cupolas of ice is much greater nearer the poles; for astronomy sometimes presents in the heavens so vast an image of them, that the rotundity of the earth seems to be considerably affected thereby. Captain Cook could never approach nearer the south pole, where there is no land, than the 70th degree of latitude; that is, no nearer than 1,500 miles; and it was only under the favor of a bay, that he was permitted to advance even so far.[81] All the results of observations made by navigators, concur in proving that the temperature of the sea decreases according to the depth; and that the deepest gulfs are continually covered with ice, even under the equator. From a late memoir by M. Perron, some say, there is reason to believe that these mountains of ice at the poles, which have hitherto impeded the progress of European navigators, have been detached from the depths of the sea to float at the surface.[82]

When water is converted into ice, it is lighter[83] than when in a fluid state, which is a circumstance of great importance. Galileo was the first who observed this. Ice consequently floats upon water, its specific gravity being to that of water as eight to nine. This rarefaction seems to be owing to the air-bubbles produced in water by freezing; and which, being considerably larger in proportion to the water frozen, render the body so much specifically lighter: these air-bubbles, during their production, acquire a great expansive power, so as to burst the containing vessels though ever so strong.

[The specific weight of ice is known to be less than
that of water. Our author assigns a reason not entirely
satisfactory. We must admit that the freezing of the upper
stratum of water, although it may _include_ the air which was
in the water frozen, yet, _it does not expel the air from the
subjacent volumes of water_. Hence the air in the water below
will balance the effects of the air included in the ice.

It is a singular fact, and is regarded as a deviation from
the general rule, that water _expands_ in volume in proportion
as its temperature is _reduced below_ 40° Fahrenheit. It also
expands by raising its temperature above this degree.

The _expansion_ of the volume then, and not the enclosed
air bubbles, is the cause of water being specifically lighter
when converted into ice. But it remains to account for its
expansion by a _reduction_ of temperature.

This is a difficult question. It seems most probable
that this expansion is owing to a peculiar arrangement, of
the particles of water, in the act of crystallization, i.e.
_freezing_. M. Mairan found that the particles of water, in
the act of freezing, arranged themselves constantly at an angle
of 60°, and by this arrangement _increased the bulk_ of the
water thus crystallized.

It is obviously a mistake to attribute the “expansive
power” of freezing to the force of the inclosed air-bubbles:
because the reduction of temperature would reduce this supposed
expansion of the inclosed air. The true cause of the expansion
of ice is supposed above, in the arrangements of the particles
of water in the process of crystallization.

The _power_ which disposes these particles to arrange,
_increases with the reduction of temperature_, until the
disposing power becomes sufficiently great to force every
impediment to the inclination to arrange. Hence the strongest
vessels burst in the process of freezing.

The impediments may restrain the accomplishment of the
arrangement of the particles for a time, but the disposing
power will overcome them, if the reduction of temperature go
on; and when they are overcome _suddenly_, the crystallization
will take place _instantly_. Hence the sudden rending of
vessels, trees, mountain rocks, &c, upon the sudden congelation
of water.

Even when there is no cause to impede crystallization, it
is well known that the _preparation_ to crystallize, or freeze,
may be observed in the liquid; the particles seeming to be
_preparing_ to arrange themselves; and then, at a given stage
of the preparation, they take their places _suddenly_, and thus
we have ice.

This consummation may be retarded, or hastened by
_artificial_ means. Water may be reduced to a lower temperature
by being kept _still_, than when _agitated_. And if it be
cooled down to the lowest possible temperature, _without
congealing_, it may remain fluid at that temperature for a long
time. But if the vessel be _suddenly struck_; or the surface
of the water _touched with a piece of ice_; or _a large piece
of cold metal be brought in contact with the outside of the
vessel; the water will instantly crystallize or freeze in
beautiful crystals_.

These facts establish the above theory. Because, 1. there
is no increased reduction of temperature effected, by striking
the vessel, touching the surface of the water with ice, or the
outside of the vessel with cold metal. 2. There is every reason
to conclude these things _commence the motion_ in the water,
which is at rest, balanced between an inclination to be at
rest, and an inclination to move in arranging the particles;
the motion communicated overcomes this balance in favor of
the disposition to crystallize, and hence the water freezes
instantly, with an expansion of volume.]

It is owing to the _expansion_ of water in freezing, that rocks and trees are often split during intense frosts. According to the calculations of the Florentine academicians, a spherule of water, only one inch in diameter, expands in freezing with a force superior to the resistance of 13½ tons weight. Major Williams also attempted to prevent this expansion; but during the operation the iron plug which stopped the orifice of the bomb-shell containing the freezing water, and which was more than two pounds weight, was projected several hundred feet with great velocity; and in another experiment the shell burst. This property of water is taken advantage of in splitting slate. At Colly Western, the slate is dug from the quarries in large blocks: these are placed in an opposite direction to what they had in the quarry, and the rain is allowed to fall on them: it penetrates their fissures, and the sharp frost freezes the water, which, expanding with its usual force, splits the slate into thin layers.[84]

M. Mairan, in a dissertation on ice, attributes the increase of its bulk chiefly to a different arrangement of the parts of the water from which it is formed; the icy skin on the water being composed of filaments, which according to him, are found to be constantly and regularly joined at an angle of 60°; and which, by this angular disposition, occupy a greater volume than if they were parallel. He found the augmentation of the volume of water by freezing, in different trials, a 14th, an 18th, a 19th, and when the water was previously purged of air, only a 22d part: that ice, after its formation, continues to expand by cold; for, after water had been frozen to some thickness, the fluid part being let out by a hole in the bottom of the vessel, a continuance of the cold made the ice convex; and a piece of ice, which was at first only a 14th part specifically lighter than water, on being exposed some days to the frost, became a 12th part lighter. To this cause he attributes the bursting of ice on ponds.

Several philosophers have been very desirous to experience how far the expansive force of freezing water might be carried. “An iron gun of an inch thickness,” says M. Haüy, “filled with water and exactly closed, having been exposed by Buot to a strong frost, was found to be burst in two places at the end of twelve hours. The Florentine philosophers were able, by means of the same cause, to burst a sphere of very thick copper; and Musschenbroek, having calculated the effort which would occasion the rupture, found that it would be capable of raising a weight of 27,720 pounds.”

“Colonel E. Williams, of the Royal Artillery, when at Quebec, in the years 1794 and 1795,” says Dr. O. Gregory, “made many experiments. He filled all sizes of iron bomb-shells with water, then plugged the fusee-hole close up, and exposed them to the strong freezing air of the winter in that climate; sometimes driving in the iron plugs as hard as possible with a sledge-hammer: and yet, though they weighed near three pounds, they were always forced out by a sudden expansion of the water in the act of freezing, like a ball impelled by gunpowder, sometimes to the distance of between 400 and 500 feet: and when the plugs were screwed in, or furnished with hooks and barbs, by which to lay hold of the inside of the shell, so that they could not possibly be forced out; in that case the shell was always split in two, though its thickness of metal was about an inch and three quarters. It is further remarkable, that through the circular crack, round about the shells where they burst, there stood out a thin film or sheet of ice, like a fin; and in the cases where the plugs were projected by freezing water, there suddenly issued from the fusee-hole a bolt of ice of the same diameter, and stood over it sometimes to the height of eight inches and a half. Hence we need not be surprised that excessive frost should cause the ice to split rocks, and other solid substances.”[85]

It was necessary for the preservation of the world, that water should in this instance be subjected to a law different from that of other substances which change from fluid to solid. The wisdom and goodness of the great ARTIFICER of the world will manifest itself in this arrangement, if we consider what would have been the consequences had water been subject to the general law, and like other fluids, become specifically heavier by the loss of its caloric. In winter, when the atmosphere became reduced to 32°, the water on the surface of our rivers would have sunk as it froze; another sheet of water would have frozen immediately, and sunk also; the ultimate consequence of which would have been, that the beds of our rivers would have become repositories of immense masses of ice, which no subsequent summer could unbind; and the world would shortly have been converted into a frozen chaos. How admirable the wisdom, how skilful the contrivance, that by subjecting water to a law contrary to what is observed by other fluids, as it freezes it becomes specifically lighter, and, swimming upon the surface, performs an important service by preserving a vast body of caloric in the _subjacent_ fluid from the effects of the surrounding cold, ready to receive its own accustomed quantity on the first change of the atmosphere?[86]

Owing to the distance of this globe from the sun, and to the vast mountains of ice at the poles, the atmosphere over a large portion of the earth is at times reduced to so low a temperature, that, if it were not for a wise provision of nature, all vegetable life must be destroyed. Caloric has always a tendency to equilibrium; therefore, if the temperature of the air be lowered, the earth cools in proportion: but when the atmosphere is reduced to 32°, the water which it held in solution becomes frozen, and precipitates in the form of snow on the earth, covering it as with a carpet, and thereby preventing the escape of that caloric which is necessary for the preservation of those families of vegetables that depend on it for their support and maturity. Be the air ever so cold, the ground, thus covered, is seldom reduced below 32°, but is maintained equably at that temperature for the purpose above mentioned.[87] Homer has described a shower of snow, and its extensive effects, in a fine strain of poetry.

“In Winter’s bleak uncomfortable reign,
A snowy inundation hides the plain:
Jove stills the winds, and bids the skies to sleep;
Then pours the silent tempest thick and deep:
And first the mountain tops are covered o’er,
Then the green fields, and then the sandy shore;
Bent with the weight the nodding woods are seen,
And one bright waste hides all the works of men:
The circling seas alone, absorbing all,
Drink the dissolving fleeces as they fall”--POPE.

Snow is furnished with the power of absorbing and combining with a large portion of oxygen, which gives it its fertilizing property. The snow melting and penetrating into the softened earth communicates to it oxygen, and this oxygen promotes the germination of seeds. The carbon of the earth combining with the oxygen, is converted into carbonic acid, and thereby acquires more solubility; while the water contributes to excite that activity which had been rendered dormant in the roots by the cold. It is this property of carbon which deprives water of the superabundant oxygen that would render it prejudicial to health, and unfit for the purposes of life. Thus what would otherwise be injurious to us is improved by the ground, and gives at the same time power and activity to the mould. How multiplied are those means which infinite wisdom and goodness employ for the preservation of the productions of Nature![88]

Ice at 32° must absorb 140° of caloric before it can become a fluid; or such a quantity as would raise a body of water of equal bulk with itself from 32° to 172°. For instance: “Take any quantity by weight of ice or snow at 32°, and mix it with an equal weight of water heated exactly to 172°. The snow instantly melts, and the temperature of the mixture is still only at _thirty-two_ degrees. Here the water is cooled 140°, while the temperature of the snow is not increased at all; so that 140° of caloric have disappeared. They must have combined with the snow; but they have only melted it, without increasing its temperature. Hence it follows irresistibly that ice, when converted into water, absorbs and combines with 140° of caloric. Water then, after being cooled down to 32°, cannot freeze till it has parted with 140° of caloric; and ice, after being heated to 32°, (which is the exact freezing point), cannot melt till it has absorbed 140° more of caloric. This is the cause of the extreme slowness of these operations. There can be no doubt, then, but water owes its fluidity to its latent caloric, and that its caloric of fluidity is 140°.”[89] And all this arrangement in nature, connected with the operation of these elements, is immediately under the control and direction of the infinitely wise and almighty Creator of the universe. “He sendeth forth his commandment upon earth: his word runneth very swiftly. He giveth snow like wool: he scattereth the hoar-frost like ashes. He casteth forth his ice like morsels: who can stand before his cold? He sendeth out his word, and melteth them: he causeth his wind to blow, and the waters flow.”

Drops of rain, falling through a cold region of the atmosphere, are frozen and converted into hail; and thus the _hail_ is produced by _rain_. When it begins to fall, it is _rain_; when it is falling, it is converted into _hail_; so that it is literally true, that _it rains hail_. The further a hail-stone falls, the larger it generally is; because, in its descent, meeting with innumerable particles of water, they become attached to it, are also frozen, and thus its bulk is continually increasing till it reaches the earth.[90] A storm of hail fell near Liverpool, in Lancashire, in the year 1795, which greatly damaged the vegetation, broke windows, &c, &c. Many of the stones measured five inches in circumference. Dr. Halley mentions a similar storm of hail in Lancashire, Cheshire, &c, April 29, 1697, that for sixty miles in length, and two miles in breadth, did immense damage, by splitting trees, killing fowls and all small animals, knocking down men and horses, &c, &c. Mezeray, in his History of France, says, that in Italy, in 1510, there was for some time a horrible darkness, thicker than that of night; after which the clouds broke into thunder and lightning, and there fell a shower of hail-stones which destroyed all the beasts, birds, and even fish of the country. It was attended with a strong smell of sulphur, and the stones were of a blueish color, some of them weighing one hundred pounds weight. The Almighty says to Job--“Hast thou seen the treasures of the hail, which I have reserved against the time of trouble, against the day of battle and war.” While God has such artillery at his command, how soon may he desolate a country, or a world![91]

The aqueous fluid is in continual circulation. The constant _round_ which it travels, says Dr. Paley, and by which, (without suffering either adulteration or waste,) it is continually offering itself to the wants of the habitable globe, is much to be admired. From the sea are exhaled, by the heat of the sun, into the air, those vapors which are there condensed into clouds: these clouds are dissolved into rain and dew, or into snow and hail, which are but rain congealed, by the coldness of the air, and descend in showers, which, penetrating into the crevices of the hills, supply the springs: which springs flow in little streams into the valleys; and there uniting, become rivers, which rivers, in return, feed the ocean. So there is an incessant circulation of the same fluid; and not one drop probably more or less now than there was at the creation. A particle of water takes its departure from the surface of the sea, in order to discharge certain important offices to the earth: and, having executed the service which was assigned to it, returns to the bosom which it left.[92] Thus, as one of the greatest of naturalists says, “All the rivers run into the sea; yet the sea is not full: unto the place from whence the rivers come, thither they return again.”

Water, when taken up by the atmosphere, is not in an aqueous state, but is converted into vapor by the efficiency of heat, and then combines with more than five times the quantity of caloric than is required to bring ice-cold water to a boiling heat, and occupies a space 800 times greater than it does when in the form of water. A large portion of the matter of heat combining chemically with water, renders it specifically _lighter_; which is the cause of its rising and mixing with the atmosphere. The waters on the face of the earth would be dissipated in vapor by a small degree of heat, if we had no atmosphere. Under the pressure of the atmosphere water boils at 212°, but in vacuo it boils when heated only to 67°. On the contrary, if additional pressure be given to water by a Papin’s digester, it may be heated to 400°, without producing ebullition. However long we boil a fluid, in an open vessel, we cannot make it in the smallest degree hotter than the boiling point.[93] When arrived at this point, the vapor absorbs the heat, and carries it off as fast as it is generated. When water is received into the atmosphere, if the air be warm, it becomes so far changed by its union with the matter of heat as to be perfectly invisible. In this state it occupies a space 1,400 times greater than its ordinary liquid state.

After vapor has remained some time in the atmosphere, it becomes in a measure condensed; and the particles of water of which it is composed unite, and form hollow vesicles, which accumulate together and produce clouds. How this is effected, those who have attentively considered the subject are not agreed. Dr. Thomson, after well investigating the matter, concludes, from all the facts, that “the formation of clouds and rain cannot be accounted for by a single principle with which we are acquainted.” It is, however, says Mr. Parkes, probable that _electricity_ alone is the primary cause. Saussure conjectures that it is the electrical fluid which surrounds these vesicles, and prevents them from dissolving in the air. And the idea of the formation of clouds by the agency of electricity was mentioned by Volta, and also by Dr. Franklin.

[It is allowed by all, that clouds are formed by the
aqueous vapors which are held suspended, or in solution, by
the atmosphere. It is not a settled question, whether the air
holds these vapors in solution, or merely suspended; and thus,
keeping the particles asunder, prevents their condensation.

This aqueous vapor is _invisible_ when perfectly in union
with the air. When it begins to separate from the air, it
becomes visible by condensation, in the form of _clouds_,
_mists_, and _fogs_. When it is perfectly separated and
sufficiently condensed it becomes _rain_, and when the
temperature is sufficiently low to freeze the condensed drops,
they become _snow_, or _hail_.

The above process is quite intelligible, but the _agent_ of
this condensation is, perhaps, inexplicable. It is impossible
to solve all the phenomena of the formation of clouds, by
supposing the vapors condensed by a reduction of temperature,
produced by the warmer volumes of clouds rising into the
regions of colder ones. For we know the natural tendency of the
warmer strata of air, from the neighborhood of the earth, is to
rise, with its watery particles, to colder regions. Hence there
would be a constant condensation, which would seem to require a
constant deposition of rain, or mist; or, at least, a constant
accumulation of clouds.

Again: On this theory, the nights would be cloudy and
rainy: as the vapors raised during the day would be condensed
by the superior coldness of the night succeeding. Moreover, it
is well known that great rains fall in very warm weather, and
when a _rise_ of temperature is observed.

These, and other considerations, have induced many persons
to have recourse to _electricity_ to solve this difficult
question, and various observations seem to countenance the
idea that it may be the remote agent of the formation of
clouds, by producing a sudden rarefaction of the air, which
would, of course, produce a sudden reduction of temperature;
the consequence of which would be a rapid condensation of the
watery particles in combination with the air. This condensation
would form clouds, and if sufficiently rapid and extensive, a
fall of rain would ensue.

This supposition is much strengthened by a fact of common
observation, viz: _when clouds are impending over us, but no
rain falling, a sudden shower comes down instantly upon a
flash of lightning._ In this case it is so obvious that the
lightning had an immediate agency, that none can doubt, who
ever observed the phenomenon.

The _electrified_ state of _clouds_, _fogs_, and _mists_,
is considered strong proof in favor of this theory. Clouds are
almost always highly charged with electricity, and sometimes so
highly charged as to become _luminous_, and very destructive.

On the 11th of August, 1772, about midnight, a bright cloud
was observed covering a mountain in the district of Cheribon,
in the island of Java, at the same time several reports were
heard like those of a gun. The people who dwelt upon the upper
parts of the mountain not being able to fly fast enough, a
great part of the cloud, almost three leagues in circumference,
detached itself under them, and was seen at a distance rising
and falling like the waves of the sea, and emitting globes of
fire so luminous, that the night became as clear as day. The
effects of it were astonishing; every thing was destroyed for
seven leagues round; the houses were demolished; plantations
were buried in the earth, and 2,140 people lost their lives.
_Ency. Brit. Article_, CLOUDS.

In another case, October 29th, 1757, in the island of
Malta, a little after midnight, there was seen to the South
west of the city Melita, a great black cloud, which, as it
approached, changed its color, till at last it became like a
flame of fire mixed with smoke. A dreadful noise was heard on
its approach, which alarmed the whole city. It passed over the
port, and came first on an English ship, which in an instant
was torn to pieces, and nothing left but the hulk; part of
the masts, sails, and cordage were carried to a considerable
distance along with the cloud. The small craft were sunk
instantly. It demolished a part of the city, and passed over to
Sicily, but did no injury there as it was previously exhausted.
Several hundred were killed. _Ency. Brit. Article_, CLOUD.]

The principle of evaporation is the primary cause of all rain, mist, dew, &c. The ocean loses many millions of gallons of water hourly by evaporation. The Mediterranean alone is said to lose more by it, than it receives from the Nile, the Tiber, the Rhone, the Po, and all the other rivers that fall into it. When Dr. Halley made his celestial observations upon the tops of the mountains at St. Helena, he found that the quantity of vapor which fell there (even when the sky was clear) was so great, that his observations were thereby much impeded: his glasses were so covered with water through the condensation of the vapors, that he was obliged to wipe them every ten minutes. In order to determine, with some degree of accuracy, how much water would be raised in vapor in any space of time, he took a vessel of water salted to the same degree with that of sea-water, in which he placed a thermometer, and by means of a pan of coals brought the water to the same degree of heat as would be produced by the sun in summer: he then affixed the vessel of water with the thermometer in it, to one end of a pair of scales, and exactly counterpoised it with weights on the other. Then, at the end of two hours, he found by the alteration in the weight of the vessel, that a sixtieth part of an inch in the depth of the water was gone off in vapor; and therefore, in twelve hours, one-tenth of an inch would have gone off. From this experiment the Doctor calculates (in as accurate a manner as the subject will admit of) the quantity of water raised by evaporation from the Mediterranean Sea, to be at least five thousand two hundred and eighty millions of tons of water in a day; and from the river Thames twenty millions three hundred thousand tons per day, on the average.

This water is conveyed by the winds to every part of the continents: these it fertilizes in the form of rain, and afterwards supplies the rivers, which flow again into the sea. In our climate, evaporation is found to be about four times as much from the vernal to the autumnal equinox, as from the autumnal to the vernal. Heat facilitates all solutions; and the greater the difference between the temperature of the air and the evaporating surface, the greater will be the evaporation. Bishop Watson found that, even when there had been no rain for a considerable time, and the earth had been dried by the parching heat of summer, an acre of ground dispersed into the air above 1,600 gallons of water in the space of twelve hours of a summer’s day. A little reflection would convince any one of the importance of the principle of evaporation. Innumerable instances of its use might be adduced; suffice to add, that without it neither grass nor corn could be sufficiently void of moisture to lay up for use. Our clothes when washed could not be dried; neither could a variety of the most common operations, which conduce much to our comfort and convenience, be performed without it.

It is evident that water exists in the atmosphere in abundance, even in the driest seasons, and under the clearest sky. By the experiments of Saussure, it appears, that a cubic foot of atmospheric air will hold eleven grains of water in solution. From this property of the air we derive many advantages. It has a tendency to preserve every thing on the face of the earth in a proper degree of moisture. It appears, from the experiments of some aëronauts, that the air is much drier in the higher regions than it is near the surface of the earth.

When two opposite currents of air meet, of different temperatures, the vapors are sometimes condensed thereby, and rain ensues. It may be remarked, that if the temperature of our atmosphere had been 212, or upwards, rain could never have fallen on the earth; for the water taken up by evaporation would have been converted into a _permanently_ elastic fluid. Such is the necessity of rain, that it _alone_ not only affords a proper degree of moisture to the vegetable creation, but is of service in bringing the soils into a fit state to perform their office. Dry earth of itself is ineffective; but when _moistened_ it has the property of decomposing atmospheric air, and of conveying its oxygen to the roots of those plants which vegetate within it. We are indebted to Humboldt for the knowledge of this fact. It is impossible ever to contemplate the various ways in which the different operations of nature are made to correct and balance each other, without being struck with the infinite comprehension of the Divine Mind, which could thus foresee the tendency of every law which it was about to establish. How many cases are there in which the slightest oversight would have produced the destruction of the world!

The effects of vapor have furnished a new moving force to mechanics, says Haüy, which it required no ordinary genius to have created, and to have measured its energy. This science, during a long time, had only employed water as a moving force, by availing itself of its natural course, or by judiciously managing its fall, so as to subject it to the operation of machines which is regulated by an impulsion continually renewed. The experiments made upon the force of water reduced to vapor, gave birth to the idea of applying that vapor so much the more advantageously to the same purpose, because independently of its great energy, it may be transported wherever it is called for by the interests of commerce and industry.

The execution of steam-engines has had, like that of all other machines, its different epochs, to which successively corresponded new degrees of perfection. To diminish, as far as possible, the quantity of vaporisation requisite for the effect in contemplation, and to make a moderate use of the combustible; to combine with this chief economy that of substance and of workmanship, by contracting the dimensions of the pieces without diminishing their utility; to prevent explosions, by the wisest precautions adopted in the management of an agent whose power becomes destructive when it is not limited: these are in general the objects which have fixed the attention of engineers, and have excited among them a laudable kind of rivalship.[94]