Mr. Daniell's explanation of the formation of rain differs from the above in some of its particulars, which are not sufficiently elementary to be given here; but it may be instructive to give a few of Mr. Howard's illustrations respecting the formation of the various clouds. If hot water be exposed to cool air, it steams—that is, the vapour given off from the surface is condensed in mixing with the air; and the water thus produced appears in visible particles, the heat of the vapour passing into the air. This effect may be seen about sunrise, in summer, on the surface of ponds warmed by the sun of the previous day, and also with water newly pumped from a well. But the small cloud formed in these instances usually disappears almost as soon as formed, the air being too dry to allow it to remain. But in the wide regions of the atmosphere the case is different, on account of the vast supply of vapour, and the ascent and descent of the cloud to regions which allow it to remain tolerably permanent. In the fine evenings of autumn, and occasionally at other seasons, mists appear suddenly in the valleys, gradually filling these low places, and even rising to a certain height, forming a foggy atmosphere for the following day. These collections of visible vapour resting on the earth, and often cut off so as to form a level surface above, so nearly resemble a sheet of water, as to have been occasionally mistaken for an inundation, the occurrence of the previous night. Such is the origin and appearance of the stratus: it constitutes the fog of the morning, and sometimes, as at the approach of a long frost, occupies the lower atmosphere for several days. But the sun, we will suppose, has broken through and dissipated this obscurity, and cleared the lower air. On looking up to the blue sky, we see some few spots showing the first formation of a cloud there: these little collections increase in number, and become clouds, heaped, as it were, on a level base, and presenting their rounded forms upwards; in which state they are carried along in the breeze, remaining distinct from each other in the sky. This is the cumulus, or heap.

By and by, if the clouds continue to form, and enough vapour is supplied from above, these heaps are seen to grow over their base like a mushroom or cauliflower. Perhaps a flat top is seen forming separately, and this afterwards joins the simple heap of cloud; or the flat forms and the heaps become mixed irregularly among each other, occupying the spaces everywhere, till the sky becomes overcast, and presents the usual appearance of dense clouds. This is the cumulo-stratus, or heaped and flat cloud. It is not productive of rain, and it forms, both in summer and in winter, the common scenery of a full sky.

On examining minutely the higher regions of the air, especially after the sky has been clear for some time, the spectator will probably see the cirrus descending from above in the form of threads or locks and feathers, which go on increasing until they fill the sky. They are more commonly seen above the two former kinds, which float upon the clear air below. On continuing to watch the cirri, they will be seen to pass to the intermediate form of cirro-cumulus, consisting of smaller rounded clouds attached to each other, or simply collected together in a flat aggregate, and forming the mottled or dappled sky.

The cumulo-stratus is more dense and continuous in its structure; thick in the middle, and thinned off towards the edges. Over-head it is a mere bed of haze, more or less dense. In the horizon, when seen sideways, it often resembles shoals of fish, as already noticed; but it is liable to put on the most ragged and patchy appearances, making a very ugly sky.

The nimbus, or rain cloud, is seen to the greatest advantage in profile, in the horizon, and at a great distance, when it often resembles a lofty tower raised by its greater height to a conspicuous place among the dark threatening clouds, and catching the sun's last rays upon its broad summit and sides. In its nearer approach, it may always be known by being connected below with an obscurity caused by the rain it lets fall, and which reaches down to the horizon.

In ascending from the lower valleys to the tops of lofty mountains, clouds may be traced through six modifications, the cirrus being seen from the loftiest summits, while the other forms are only skirting the sides of the mountains. Mr. Mason remarks, that clouds occasionally lie so low, that before the balloon seems to have entirely quitted the earth, it has been received between their limits, and entirely enveloped within their watery folds. Clouds, on the contrary, are sometimes at such a height, that the balloon either never comes into contact with them at all, or, if it passes through one layer, the aeronaut continues to behold another occupying a still remoter region of the skies above.

As a general rule, it is stated that the natural region of clouds is a stratum of the atmosphere lying between the level of the first thousand feet, and that of one removed about ten thousand feet above it. Of course it is not supposed but that clouds are occasionally found on both sides of the bounds here assigned to them; the mist occupies the lowest valleys, while, on the other hand, long after the aeronaut has attained the height of ten thousand feet, some faint indications of clouds may still be seen partially obscuring the dark blue vault above him. As he continues to ascend, the blue of the sky increases in intensity; and should a layer of clouds shut out all view of the earth, "above and all around him extends a firmament dyed in purple of the intensest hue; and from the apparent regularity of the horizontal plane on which it rests, bearing the resemblance of a large inverted bowl of dark blue porcelain standing upon a rich Mosaic floor or tesselated pavement. Ascending still higher, the colour of the sky, especially about the zenith, is to be compared with the deepest shade of Prussian blue."

[Picture: Various forms of hail-stones]



CHAPTER IV.

ON HAIL—THE HAIL-STORMS OF FRANCE—DISASTROUS EFFECTS OF HAIL—THE HAIL-STORMS OF SOUTH AMERICA—THEIR SURPRISING EFFECTS—ORIGIN AND NATURE OF HAIL—PERIODICAL FALLS OF HAIL—HAIL CLOUDS—HAILSTONES—THEIR VARIOUS FORMS—EXTRAORDINARY SIZE OF HAILSTONES.

As hail seems to be nothing more than frozen rain, it is necessary to collect a few particulars respecting it in this place.

Great Britain is essentially a rain country; but there are some parts of the world which have obtained the unhappy distinction of being hail countries: such, for example, as some of the most beautiful provinces of France, which are frequently devastated by hail-storms. One of the most tremendous hail-storms on record is that which occurred in that country in July 1788. This fearful storm was ushered in by a dreadful and almost total darkness which suddenly overspread the whole country. In a single hour the whole face of nature was so entirely changed, that no person who had slept during the tempest could have believed himself in the same part of the world when he awoke. Instead of the smiling bloom of summer, and the rich prospects of a forward autumn, which were just before spread over the face of that fertile and beautiful country, it now presented the dreary aspect of an arctic winter. The soil was changed into a morass; the standing corn beaten into a quagmire; the vines were broken to pieces, and their branches bruised in the same manner; the fruit-trees of every kind were demolished, and the hail lay unmelted in heaps like rocks of solid ice. Even the robust forest trees were incapable of withstanding the fury of the tempest; and a large wood of chesnut trees, in particular, was so much damaged, that it presented, after the storm, little more than bare and naked trunks. The vines were so miserably hacked and battered, that four years were estimated as the shortest period in which they could become again in any degree productive. Of the sixty-six parishes included in the district of Pontoise, forty-three were entirely desolated; while, of the remaining twenty-three, some lost two-thirds, and others above half their harvest.

This storm began in the south, and proceeded in two parallel bands from the south-west to the north-east; the extent of one of them being 175 leagues, and of the other 200; thus traversing nearly the whole length of that great kingdom, and even a portion of the Low countries. The mean breadth of the eastern portion was four leagues, and of the western two: and, what is very remarkable, the interval between the two bands, amounting to five leagues, was deluged with heavy rain. The largest of the hail-stones weighed half a pound each.

The progress of this storm, which was from south to north, was at the rate of 16.5 leagues an hour; and the velocity of the two bands was precisely the same. The continuance of the hail was limited to seven or eight minutes, at each of the principal stations marked.

There are instances, however, on record, in which hail has produced even more tremendous results than those above recorded. In some parts of South America hail-stones are sometimes so large and so hard, and fall with such violence, that large animals are killed by them. Mr. Darwin, encamping at the foot of the Sierra Tapalguen, says:—"One of the men had already found thirteen deer lying dead, and I saw their fresh hides. Another of the party, a few minutes after my arrival, brought in seven more. Now I well know that one man without dogs could hardly have killed seven deer in a week. The men believed they had seen about fifteen dead ostriches, (part of one of which we had for dinner;) and they said that several were running about evidently blind in one eye. Numbers of small birds, as ducks, hawks, and partridges, were killed. I saw one of the latter with a black mark on its back, as if it had been struck with a paving-stone. A fence of thistle-stalks round the hovel was nearly broken down; and my informer, putting his head out to see what was the matter, received a severe cut, and now wears a bandage. The storm was said to have been of limited extent: we certainly saw, from our last night's bivouac, a dense cloud and lightning in this direction. It is marvellous how such strong animals as deer could thus have been killed; but, I have no doubt, from the evidence I have given, that the story is not in the least exaggerated." Dr. Malcolmson informed Mr. Darwin, that he witnessed, in 1831, in India, a hail-storm, which killed numbers of large birds, and much injured the cattle. These hail-stones were flat; one was ten inches in circumference; and another weighed two ounces. They ploughed up a gravel-walk like musket-balls, and passed through glass windows, making round holes, but not cracking them.

There is much in the origin and formation of hail that cannot well be explained. Volta regarded the formation of small flakes of ice, the kernels of future hail-stones, in the month of July, during the hottest hours of the day, as one of the most difficult phenomena in nature to explain. It is difficult to account for the comparative scarcity of hail-showers in winter; as also, for the great size which hailstones are often known to attain.

It appears from certain resemblances in the descents of rain, snow, and hail, that they have a common origin, their different formations being explained by difference of temperature. Howard has observed a huge nimbus affording hard snowballs and distinct flakes of snow at the same time. Hail and rain are by no means uncommon from the same cloud. The size of a cloud may be such, or clouds may exist in different elevations, which in an upper region produce hail, in a lower region snow, and at a still lower elevation rain. Rain may also form in an upper region of the sky, and descend into a colder stratum of the atmosphere, and be frozen into hail. Hail generally precedes storms of rain.

Change of wind and the action of opposite currents, so necessary for the production of rain, are also frequent during hail-storms. While clouds are agitated with the most rapid motions, rain generally falls in greatest abundance; and if the agitation be very great it generally hails. Before the descent of hail a noise is heard, a particular kind of crackling, which has been compared to the emptying of a bag of walnuts.

The descent of hail in some countries appears to occur at particular periods. In the central parts of France, Italy, and Spain, it usually hails most abundantly during the warmest hours of the day in spring and summer, and in Europe generally it falls principally during the day; but there are examples recorded of great hail-storms which have taken place during the night. Near the equator, it seldom hails in places situated at a lower level than 350 fathoms, for, although the hail may be formed, the warmth of the regions prevents it from falling in that state.

The appearance of hail clouds seems to be distinguished from other stormy clouds by a very remarkable shadowing. Their edges present a multitude of indentations, and their surfaces disclose here and there immense irregular projections. Arago has seen hail-clouds cover with a thick veil the whole extent of a valley, at a time when the neighbouring hills enjoyed a fine sky and an agreeable temperature.

Hailstones of similar forms are produced at similar levels. They are smaller on the tops of mountains than in the neighbouring plains. If the temperature or the wind alter, the figures of the hailstones become immediately changed. Hailstones of the form of a six-sided pyramid have been known to change, on the wind changing to the north-east, to convex lenses, so transparent and nicely formed, that they magnified objects without distorting them. Some hailstones are globular, others elongated, and others armed with different points.

In the centres of hailstones small flakes of spungy snow are frequently found, and this usually is the only opaque point in them. Sometimes the surface is covered with dust, like fine flour, and is something between hail and snow. This never falls during summer in southerly countries. In the Andes hailstones from five to seven lines in diameter are sometimes formed of layers of different degrees of transparency, so as to permit rings of ice to be separated from them with a very slight blow. In Orkney, hailstones have fallen as finely polished as marbles, of a greyish white colour, not unlike fragments of light-coloured marble. Hailstones are often so hard and elastic, that those which fall on the stones rebound without breaking to the height of several yards; and they have been known to be projected from a cloud almost horizontally, and with such velocity as to pierce glass windows with a clear round hole.

On the 7th May, 1822, some remarkable hailstones fell at Bonn, on the Rhine. Their general size was about an inch and a half in diameter, and their weight 300 grains. When picked up whole, which was not always the case, their general outline was elliptical, with a white, or nearly opaque spot in the centre, about which were arranged concentric layers, increasing in transparency to the outside. Some of them exhibited a beautiful star-like and fibrous arrangement, the result of rows of air bubbles dispersed in different radii. The figures at the head of this chapter show the external and internal appearances of these hailstones.

The smaller figures represent pyramidal hail, common in France, and occasionally in Great Britain.

Brown hailstones have been noticed. Humboldt saw hail fall of the colour of blood.

On the 15th July, 1808, Howard noticed, in Gloucestershire, hailstones from three to nine inches in circumference; appearing like fragments of a vast plate of ice which had been broken in its descent to the earth.

On the 4th June, 1814, Dr. Crookshank noticed, in North America, hailstones of from thirteen to fifteen inches in circumference. They seemed to consist of numerous smaller stones fused together.

On the 24th July, 1818, during a storm in Orkney, Mr. Neill picked up hailstones weighing from four ounces to nearly half a pound.

[Picture: Rain gauges]



CHAPTER V.

METHOD OF MEASURING THE QUANTITY OF RAIN THAT FALLS—THE RAIN GAUGE—METHODS OF OBSERVING FOR RAIN AND SNOW—EFFECTS OF ELEVATION ON THE QUANTITY OF RAIN—DIFFERENCE BETWEEN THE TOP OF A TALL BUILDING AND THE SUMMIT OF A MOUNTAIN—SIZE OF DROPS OF RAIN—VELOCITY OF THEIR FALL—QUANTITY OF RAIN IN DIFFERENT LATITUDES—EXTRAORDINARY FALLS OF RAIN—REMARKS ON THE RAIN OF THIS COUNTRY—INFLUENCE OF THE MOON—ABSENCE OF RAIN—REMARKABLE DROUGHT IN SOUTH AMERICA—ITS TERRIBLE EFFECTS AND CONSEQUENCES—ARTIFICIAL RAINS.

The quantity of rain which falls at different parts of the earth's surface is very variable; and for the purpose of measuring it instruments called Rain-gauges have been contrived. The simplest form is a funnel three or four inches high, and having an area of one hundred square inches. This may be placed in the mouth of a large bottle, and, after each fall of rain, the quantity may be measured by a glass jar divided into inches and parts. This simple gauge being placed on the ground in an open spot, will evidently represent a portion of the ground, and will show the depth of rain which would cover it at and about that spot, supposing the ground to be horizontal, and that the water could neither flow off nor sink into the soil. Thus, by taking notice of the quantity of rain which falls day by day, and year by year, and taking the average of many years, we get the mean annual quantity of rain for the particular spot in question. By an extension of these observations, it is evident that the mean annual fall of rain may be known for a district or a kingdom.

A more convenient form of rain-gauge than the one just noticed, is made by placing the funnel at the top of a brass or copper cylinder, connected with which at the lower point, is a glass tube with a scale, measuring inches and tenths of an inch. The water stands at the same height in the glass tube as it does in the cylinder, and being visible in the tube the height can be immediately read on the scale. The cylinder and the tube are so constructed, that the sum of the areas of their sections is a given part, such as a tenth of the area of the mouth of the funnel; so that each inch of water in the tube is equal to the tenth of an inch of water which enters the mouth of the funnel. A stop-cock is added for drawing off the water from the cylinder after each observation is noted down.

Some rain-gauges are constructed for showing the quantity of rain which falls from each of the four principal quarters. Others are made so as to register, themselves, the quantity of rain fallen. One of this kind, by Mr. Crosley, consists of a funnel through which the rain passes to a vibrating trough; when, after a sufficient quantity has fallen into its higher side, it sinks down and discharges the rain which escapes by a tube. The vibrating action of this trough moves a train of wheel-work and indices, which register upon a dial plate the quantity of rain fallen.

Whatever form of rain-gauge is adopted, it must be placed in an exposed situation, at a distance from all buildings, and trees, and other objects likely to interfere with the free descent of rain into the funnel. It is usual, in rainy weather, to observe the quantity of water in the gauge every morning; but this does not seem to be often enough, considering how freely water evaporates in an exposed situation. An error may also arise from some of the water adhering to the sides of the vessel, unless an allowance is made for the quantity thus lost by a contrivance such as the following:—Let a sponge be made damp, yet so that no water can be squeezed from it, and with this collect all the water which adheres to the funnel and cylinder, after as much as possible has been drawn off; then, if the sponge be squeezed, and the water from it be received in a vessel which admits of measuring its quantity, an estimate may be made of the depth due to it; and this being added to the depth given by the instrument, would probably show correctly the required depth of rain.

When snow has fallen the rain-gauge may not give a correct quantity, as a portion of it may be blown out, or a greater quantity may have fallen than the mouth will contain. In such cases, it is recommended to take a cylindrical tube and press it perpendicularly into the snow, and it will bring out with it a cylinder equal to the depth. This, when melted, will give the quantity of water which can be measured as before. The proportion of snow to water is about seventeen to one; and hail to water, about eight to one. These quantities, however, may vary according to the circumstances under which the snow or hail has fallen, and the time they have been upon the ground.

The rain-gauge should be placed as near the surface of the ground as possible; for it is a perplexing circumstance, that the rain-gauge indicates very different quantities of rain as falling upon the very same spot, according to the different heights at which it is placed. Thus it has been found, that the annual depth of rain at the top of Westminster Abbey was 12.1 inches nearly, while, on the top of a house sixteen feet lower, it was rather more than 18.1 inches, and on the ground, in the garden of the house, it was 22.6 inches. M. Arago has also found from observations made during twelve years, that on the terrace of the Observatory at Paris the annual depth was about 2.25 inches less than in the court thirty yards below.

It would naturally be expected from these observations, that less rain falls on high ground than at the level of the sea. Such however is not the case, except on abrupt elevations; where the elevation is made by the natural and gradual slope of the earth's surface, the quantity of rain is greater on the mountain than in the plain. Thus, on the coast of Lancashire, there is an annual fall of 39 inches; while at Easthwaite, among the mountains in the same county, the annual depth of rain amounts to 86 inches. By comparing the registers at Geneva and the convent of the Great St. Bernard, it appears that at the former place, by a mean of thirty-two years, the annual fall of rain is about 30.75 inches; while at the latter, by a mean of twelve years, it is a little over 60 inches.

In order to explain these remarkable differences, it must not be supposed that the clouds extend down to the ground, so as to cause more rain at the foot of Westminster Abbey than on its roof. There is no doubt that in moist weather the air contains more water near the ground than a few hundred feet above it; and probably, the same cause which determined a fall from the cloud, would also throw down the moisture floating at a low elevation. Much rain also proceeds from drifting showers, of short duration, and the current moves more slowly along the surface, and allows the drops to fall as fast as they are formed. In hilly countries, on the contrary, clouds and vapours rest on the summits without descending into the plains, and, according to some, the hills attract electricity from the clouds, and thus occasion rain to fall. Mr. Phillips supposes that each drop of rain continues to increase in size from the commencement to the end of its descent, and as it passes successively through the moist strata of the air, obtains its increase from them; while the rain which falls on the mountain may leave these moist strata untouched, so that they may, in fact, not form rain at all.

The drops of rain are of unequal size, as may be seen from the marks made by the first drops of a shower upon any smooth surface. They vary in size from perhaps the twenty-fifth to a quarter of an inch in diameter. It is supposed that in parting from the clouds they fall with increasing speed, until the increasing resistance of the air becomes equal to their weight, when they continue to fall with an uniform velocity. A thunder-shower pours down much faster than a drizzling rain. A flake of snow, being perhaps nine times more expanded than water, descends thrice as slow. But hailstones are often several inches in length, and fall with a velocity of seventy feet in a second, or at the rate of about fifty miles an hour, and hence the destructive power of these missiles in stripping and tearing off fruit and foliage.

The annual quantity of rain decreases from the equator to the poles, as appears from the following table, which gives the name of the station, its latitude, and the average annual number of inches of rain:—

Coast of Malabar lat. 11 degrees 30' 135.5 inches. N. At Grenada, Antilles 12 degrees 126 At Cape Francois, St. 19 degrees 46' 120 Domingo At Calcutta 22 degrees 23' 81 At Rome 41 degrees 54' 39 In England 50 to 55 degrees 31 At St. Petersburgh 59 degrees 16' 16 At Uleaborg 65 degrees 30' 13.5

The number of rainy days, on the contrary, increases from the equator to the poles.

From 12 to 43 degrees N. lat.—the number of rainy days in 78 the year amounts to From 43 to 46 degrees 103 From 46 to 50 degrees 134 From 50 to 60 degrees 161

The greatest depth of rain which falls in the Indian ocean is during the time when the periodical winds, called the monsoons, change their direction. When the winds blow directly in-shore the rains are very abundant, so much so that, after a continuance of twenty-four hours, the surface of the sea has been covered with a stratum of fresh water, good enough for drinking, and ships have actually filled their casks from it. Colonel Sykes observes, that the deluge-like character of a monsoon in the Ghats of Western India, is attested by the annual amount of 302.25 inches, at Malcolmpait, on the Mahabuleshwar Hills.

A great depth of rain in a short time has occasionally been witnessed in Europe. At Genoa, on the 25th of October, 1822, a depth of thirty inches of rain fell in one day. At Joyeuse, on the 9th of October, 1827, thirty-one inches of rain fell in twenty-two hours. Previous to the great floods of Moray, in 1829, the rain is described as being so thick that the very air itself seemed to be descending in one mass of water upon the earth. Nothing could withstand it. The best finished windows were ineffectual against it, and every room exposed to the north-east was deluged. The smaller animals, the birds, and especially game, of all kinds, were destroyed in great numbers by the rain alone, and the mother partridge, with her brood and her mate, were found chilled to death amidst the drenching wet. It was also noticed, that, as soon as the flood touched the foundation of a dry stone wall, the sods on the top of it became as it were alive with mice, all forcing their way out to escape from the inundation which threatened their citadel; and in the stables, where the water was three feet deep, rats and moles were swimming about among the buildings.

Among the Andes it is said to rain perpetually; but in Peru it never rains, moisture being supplied during a part of the year by thick fogs, called garuas. In Egypt, and some parts of Arabia, it seldom rains at all, but the dews are heavy, and supply with moisture the few plants of the sandy regions.

There is a great variation in the quantity of rain that falls in the same latitude, on the different sides of the same continent, and particularly of the same island. The mean fall of rain at Edinburgh, on the eastern coast, is 26 inches; while at Glasgow, on the western coast, in nearly the same latitude, it is 40 inches. At North Shields, on the eastern coast, it is 25 inches; while at Coniston, in Lancashire, in nearly the same latitude, on the western coast, it is 85 inches.

The amount of rain in a district may be changed by destroying or forming forests, and by the inclosure and drainage of land. By thinning off the wood in the neighbourhood of Marseilles, there has been a striking decrease of rain in fifty years.

In Mr. Howard's observations on the climate of this country, he has found, on an average of years, that it rains every other day; that more rain falls in the night than in the day; that the greatest quantity of rain falls in autumn, and the least in winter; that the quantity which falls in autumn is nearly double that in spring; that most rain falls in October and least in February, and that May comes nearest to the mean: that one year in every five, in this country, may be expected to be extremely dry, and one in ten extremely wet.

According to Dalton, the mean annual amount of rain and dew for England and Wales is 36 inches. The mean all over the globe is stated to be 34 inches.

There seems to be some real connexion between the changes of the moon and the weather. Mr. Daniell says, "No observation is more general; and on no occasion, perhaps, is the almanac so frequently consulted as in forming conjectures upon the state of the weather. The common remark, however, goes no further than that changes from wet to dry, and from dry to wet, generally happen at the changes of the moon. When to this result of universal experience we add the philosophical reasons for the existence of tides in the aerial ocean, we cannot doubt that such a connexion exists. The subject, however, is involved in much obscurity." At Viviers, it was observed that the number of rainy days was greatest at the first quarter, and least at the last. Mr. Howard has observed that, in this country, when the moon has south declination, there falls but a moderate quantity of rain, and that the quantity increases till she has attained the greatest northern declination. He thinks there is "evidence of a great tidal wave, or swell in the atmosphere, caused by the moon's attraction, preceding her in her approach to us, and following slowly as she departs from these latitudes."

Most dry climates are subject to periodical droughts. In Australia, they return after every ten or twelve years, and are then followed by excessive rains, which gradually become less and less till another drought is the consequence.

When Mr. Darwin was in South America, he passed through a district which had long been suffering from dry weather. The first rain that had fallen during that year was on the 17th of May, when it rained lightly for about five hours. "With this shower," he says, "the farmers, who plant corn near the sea-coast, where the atmosphere is more humid, would break up the ground; with a second, put the seed in; and, if a third should fall, they would reap in the spring a good harvest. It was interesting to watch the effect of this trifling amount of moisture. Twelve hours afterwards the ground appeared as dry as ever; yet, after an interval of ten days, all the hills were faintly tinged with green patches; the grass being sparingly scattered in hair-like fibres a full inch in length. Before this shower every part of the surface was bare as on a high road."

A fortnight after this shower had fallen, Mr. Darwin took an excursion to a part of the country to which the shower had not extended. "We had, therefore," he says, "in the first part of our journey a most faint tinge of green, which soon faded away. Even where brightest, it was scarcely sufficient to remind one of the fresh turf and budding flowers during the spring of other countries. While travelling through these deserts, one feels like a prisoner, shut up in a gloomy courtyard, longing to see something green, and to smell a moist atmosphere."

The effects of a great drought in the Pampas are thus described. "The period included between the years 1827 and 1830 is called the 'gran seco' or the great drought. During this time so little rain fell, that the vegetation, even to the thistles, failed; the brooks were dried up, and the whole country assumed the appearance of a dusty high road. This was especially the case in the northern part of the province of Buenos Ayres, and the southern part of St. Fe. Very great numbers of birds, wild animals, cattle, and horses, perished from the want of food and water. A man told me that the deer used to come into his courtyard to the well which he had been obliged to dig to supply his own family with water; and that the partridges had hardly strength to fly away when pursued. The lowest estimation of the loss of cattle in the province of Buenos Ayres alone, was taken at one million head. A proprietor at San Pedro had previously to these years 20,000 cattle; at the end not one remained. San Pedro is situated in the midst of the finest country, and even now again abounds with animals; yet, during the latter part of the 'gran seco' live cattle were brought in vessels for the consumption of the inhabitants. The animals roamed from their estancias, and wandering far to the southward, were mingled together in such multitudes that a government commission was sent from Buenos Ayres to settle the disputes of the owners. Sir Woodbine Parish informed me of another and very curious source of dispute; the ground being so long dry, such quantities of dust were blown about, that in this open country the landmarks became obliterated, and people could not tell the limits of their estates.

"I was informed by an eye-witness, that the cattle in herds of thousands rushed into the river Parana, and being exhausted by hunger they were unable to crawl up the muddy banks, and thus were drowned. The arm which runs by San Pedro was so full of putrid carcasses, that the master of a vessel told me, that the smell rendered it quite impossible to pass that way. Without doubt, several hundred thousand animals thus perished in the river. Their bodies, when putrid, floated down the stream, and many in all probability were deposited in the estuary of the Plata. All the small rivers became highly saline, and this caused the death of vast numbers in particular spots, for when an animal drinks of such water it does not recover. I noticed, but probably it was the effect of a gradual increase, rather than of any one period, that the smaller streams in the Pampas were paved with bones. Subsequently to this unusual drought, a very rainy season commenced, which caused great floods. Hence it is almost certain, that some thousands of these skeletons were buried by the deposits of the very next year. What would be the opinion of a geologist viewing such an enormous collection of bones, of all kinds of animals and of all ages, thus embedded in one thick earthy mass? Would he not attribute it to a flood having crept over the surface of the land, rather than to the common order of things?"

Captain Owen mentions a curious effect of a drought on the elephants at Benguela on the western coast of Africa:—"A number of these animals had some time since entered the town in a body to possess themselves of the wells, not being able to procure any water in the country. The inhabitants mustered, when a desperate conflict ensued, which terminated in the ultimate discomfiture of the invaders, but not until they had killed one man, and wounded several others." The town is said to have a population of nearly three thousand. Dr. Malcolmson states, that during a great drought in India the wild animals entered the tents of some troops at Ellore, and that a hare drank out of a vessel held by the adjutant of the regiment.

In connexion with droughts may be mentioned a plan {133} proposed by Mr. Espy of the United States of America, for remedying them by means of artificial rains. That gentleman says, that if a large body of heated air be made to ascend in a column, a large cloud will be generated, and that such cloud will contain in itself a self-sustaining power, which may move from the place over which it was formed, and cause the air over which it passes to rise up into it and thus form more cloud and rain, until the rain may become general.

It is proposed to form this ascending column of air by kindling large fires which, Mr. Espy says, are known to produce rain. Humboldt speaks of a mysterious connexion between volcanoes and rain, and says that when a volcano bursts out in South America in a dry season, it sometimes changes it to a rainy one. The Indians of Paraguay, when their crops are threatened by drought, set fire to the vast plains with the intention of producing rain. In Louisiana, heavy rains have been known from time immemorial to succeed the conflagration of the prairies; and the inhabitants of Nova Scotia bear testimony to a similar result from the burning of their forests. Great battles are said to produce rain, and it is even stated that the spread of manufactures in a particular district deteriorates the climate of such district, the ascending current occasioned by the tall chimney of every manufactory tending to produce rain. In Manchester, for example, it is said to rain six days out of seven.

[Picture: Decorative picture of person by pool]

[Picture: Decorative picture of pastoral scene with rainbow]



CHAPTER VI.

THE RAINBOW—DECOMPOSITION OF WHITE LIGHT BY THE PRISM—FORMATION OF PRIMARY AND SECONDARY BOWS—RAINBOWS IN MOUNTAIN REGIONS—THE RAINBOW A SACRED EMBLEM—LUNAR RAINBOW—LIGHT DECOMPOSED BY CLOUDS—THEIR BEAUTIFUL COLOURS—EXAMPLES.

By means of rain and rain clouds we get that beautiful appearance so well known as the rainbow. In order to form some idea of the manner in which the rainbow is produced, it is necessary to know something of the manner in which light is composed. Sir Isaac Newton was the first philosopher who clearly explained the composition of light, as derived from the sun. He admitted a ray of the sun into a darkened room through a small hole in the window shutters; in front of this hole he placed a glass prism, and at a considerable distance behind the prism he placed a white screen. If there had been no prism between the hole and the screen, the ray of light would have proceeded in the direction of the dotted lines, and a bright spot would have fallen upon the floor of the room, as shown in the figure. But the effect of the prism is to refract or bend the ray out of its ordinary course, and in doing so it does not produce a white spot upon the screen, but a long streak of beautiful colours, in the order marked in the figure, red being at the bottom, then orange, yellow, green, blue, indigo, and violet at the top.

[Picture: Decomposition of white light]

In order to account for the production of these colours from a ray of light, Newton supposed that such a ray is actually made up of seven distinct colours, which being mixed in proper proportions neutralize or destroy each other. In order to account for the decomposition of the ray of white light by the prism, and for the lengthened form of the spectrum, as it is called, he supposed that each of the seven coloured rays was capable of being bent by the prism in a different manner from the rest. Thus, in the figure, the red appears to be less bent out of the direction of the original ray than the orange—the orange less than the yellow, and so on until we arrive at the violet, which is bent most of all.

It is scarcely necessary to remark, that these views were found to be correct, except as regards the number of colours in the solar spectrum; for it is now ascertained, with tolerable certainty, that there are only three primitive or pure colours in nature, and these are red, yellow, and blue; and it is supposed that by mingling two or more of these colours in various proportions, all the colours in nature are produced.

Now, to apply this explanation to the production of the rainbow, which is usually seen under the following circumstances:—The observer is placed with his back to the sun, and at some distance before him rain is falling,—the air between the sun and the rain being tolerably clear. He then often sees two circular arcs or bows immediately in front of him. The colours of the inner bow are the more striking and vivid of the two. Each exhibits the same series of colours as in the spectrum formed by the prism; namely, red, orange, yellow, green, blue, indigo, and violet; but the arrangement of these colours is different in the two bows, for while in the inner bow the lower edge is violet and the upper red, in the outer bow the lower edge is red and the upper violet. The production of both bows is due to the refraction and reflexion of light, the drops of rain forming, in fact, the prism which decomposes the white light of the sun. The colours in the rainbow have the same proportional breadth as the spaces in the prismatic spectrum. "The bow is, therefore," as Sir D. Brewster remarks, "only an infinite number of prismatic spectra, arranged in the circumference of a circle; and it would be easy, by a circular arrangement of prisms, or by covering up all the central part of a large lens, to produce a small arch of exactly the same colours. All we require, therefore, to form a rainbow, is a great number of transparent bodies capable of forming a great number of prismatic spectra from the light of the sun."

The manner in which the drops of rain act as prisms, may, perhaps, be better understood with the assistance of the following diagram. Suppose the two lower circles to represent drops of rain which assist in forming the primary bow, and the two upper circles similar drops which help to produce the secondary bow; and let S represent rays of the sun falling upon them. The rays of the sun fall upon every part of the drop; but, as those which pass through or near the centre come out on the opposite side and form a focus, they need not be taken into account. Those rays, however, which fall on the upper side of the drops, will be bent or refracted, the red rays least, and the violet most; and will fall upon the back of the drop in such a manner as to be reflected to the under part of the drop; on quitting which they will be again refracted, so as to be seen at E, where there will appear to the observer a prismatic spectrum with the red uppermost, and the violet undermost. These remarks apply to those drops only which form the upper part of the bow, but it is obvious that a similar reasoning applied to the drops to the right and left of the observer, will complete the bow. The inclination of the red ray and the violet ray to the sun's rays, is 42 degrees 2' for the red, and 40 degrees 17' for the violet, so that the breadth of the primary bow is 1 degrees 45'.

Thus it will be seen, that the primary bow is produced by two refractions, and one intermediate reflection of the rays that fall on the upper sides of the drops of rain. It is different with the rays which enter the drops below. The red and violet rays will be bent or refracted in different directions; and, after being twice reflected, will be again bent towards the eye of the observer at E; but in this case the violet forms the upper part, and the red the under part of the spectrum. The inclination of these rays to the sun's rays at S, is 50 degrees 58' for the red ray, and 54 degrees 10' for the violet ray; so that the breadth of the bow is 3 degrees 10', and the distance between the primary and secondary bows is 8 degrees 15'. Hence the secondary is formed in the outside of the primary bow, with its colours reversed, in consequence of their being produced by two reflexions and two refractions. The colours of the secondary bow are much fainter than those of the primary, because they undergo two reflexions instead of one.

There is something very wonderful in the rapidity and perfection with which these natural prisms, the falling drops of rain, produce these effects. In the inconceivably short space of time occupied by a drop falling through those parts of the sky which form the proper angles with the sun's rays and the eye of the observer, the light enters the surface of the drop, undergoes within it one or two reflexions, two refractions and decompositions, and has reached the eye; and all this is done in a portion of time too small for the drop to have fallen through a space which we have the means of measuring.

It will be understood, that since the eyes of different observers cannot be in precisely the same place at the same time, no two observers can see the same rainbow; that is to say, the bow produced by one set of drops to the eye of one observer is produced by another set of drops to the eye of another observer.

A rainbow can never be greater than a semicircle, unless the spectator is on elevated ground; for if it were greater than a semicircle the centre of the bow would be above the horizon, while the sun, which must be in a line drawn through that centre and the eye of the observer, would be below the horizon: but in such a case, the sun could not shine on the drops of rain, and consequently there could be no rainbow.

When the rain cloud is of small extent only a portion of a bow is visible; when the cloud overspreads a large part of the sky a perfect bow appears. Sometimes the bow may be traced across a portion of blue sky, or it may appear to rest on the ground. In the former case, there are vapours in the air too thin to be seen, but sufficient to refract and reflect the rays of light; in the latter, the drops of rain, adhering to the grass and foliage, produce the same effect. A coloured bow, similar to that produced by rain, is sometimes seen in the spray of a fountain or of a water-fall, and also in mists that lie low upon the ground.

In mountainous and stormy regions rainbows are often seen to great advantage. In the islands off the Irish coast the author of "Letters from the Irish Islands," describes the rainbow of winter "as gradually advancing before the lowering clouds, sweeping with majestic stride across the troubled ocean, then, as it gained the beach, and seemed almost within one's grasp, vanishing amid the storm of which it had been the lovely but treacherous forerunner. It is, I suppose, a consequence of our situation, and the close connexion between sea and mountain, that the rainbows here are so frequent and so peculiarly beautiful. Of an amazing breadth, and of colours vivid beyond description, I know not whether most to admire this aerial phenomenon, when suspended in the western sky, one end of the bow sinks behind the Island of Boffin, while at the distance of several leagues the other rests upon the misty hills of Ennis Turc; or when, at a later hour of the day, it has appeared stretched across the ample sides of Mulbrea, penetrating far into the deep blue waters that flow at its base. With feelings of grateful recollection, too, we may hail the repeated visits of this heavenly messenger, occasionally as often as five or six times in the course of the same day, in a country exposed to such astonishing, and, at times, almost incessant floods of rain."

The beauty of the rainbow is not the only reason why we should regard it with interest. The rainbow was appointed by God himself as a sign of the covenant of mercy, made with Noah and with all mankind, after the flood. The words in which this declaration was made to mankind, are recorded in the Book of Genesis, chap. ix. ver. 11 to 16.

Burnet, in his "Sacred Theory of the Earth," has some remarks on the first appearance of the rainbow to the inhabitants of the earth after the deluge. He says, "How proper and how apposite a sign would this be for Providence to pitch upon, to confirm the promise made to Noah and his posterity, that the world should be no more destroyed by water! It had a secret connexion with the effect itself, and was so far a natural sign; but, however, appearing first after the deluge, and in a watery cloud, there was, methinks, a great easiness and propriety of application for such a purpose. And if we suppose, that while God Almighty was declaring his promise to Noah, and the sign of it, there appeared at the same time in the clouds a fair rainbow, that marvellous and beautiful meteor which Noah had never seen before; it could not but make a most lively impression upon him, quickening his faith, and giving him comfort and assurance that God would be stedfast to his promise."

A rainbow is sometimes formed by the rays of the moon falling upon drops of rain, in the same manner as the solar rays, and refracted and reflected by the drops; but the colours are faint in consequence of the feeble light of the moon compared with that of the sun. A lunar rainbow has been thus described by an observer:—"The moon was truly 'walking in brightness,' brilliant as she could be, not a cloud was to be seen near her; and over against her, toward the north-west, or perhaps rather more to the north, was a rainbow, a vast arch, perfect in all its parts, not interrupted or broken as rainbows frequently are, but unremittedly visible from one horizon to the other. In order to give some idea of its extent, it is necessary to say, that, as I stood toward the western extremity of the parish of Stoke Newington, it seemed to take its rise from the west of Hampstead, and to end perhaps in the river Lea, the eastern boundary of Tottenham. Its colour was white, cloudy, or greyish, but a part of its western limb seemed to exhibit tints of a faint sickly green. After some time the moon became darkened by clouds, and the rainbow of course vanished."

[Picture: Lunar Rainbow]

The brilliant colours of the solar rainbow are frequently produced by the clouds without any prismatic arrangement. The light of the sun is decomposed by a process called absorption: for example, white light is composed of red, yellow, and blue rays, in certain proportions; now, if in passing through, or falling upon any substance whatever, the red rays are stifled or absorbed, while the yellow and blue are allowed to pass or to be reflected, it is obvious that such a substance cannot appear white, because one of the elements of white light, namely, the red, is wanting; it must therefore appear of such a colour as results from the combination of yellow and blue; the substance will therefore appear green. So, also, when white light falls upon what we call a red surface, the yellow and blue rays are stifled or absorbed, leaving the red only to be reflected. Now, when we consider the various ways in which this absorption may take place; one or two, or all of the coloured rays being absorbed in every possible proportion, it is easy to form some idea of the manner by which the innumerable tints of the sky are produced.

It has been calculated, that, of the horizontal sunbeams which pass through two hundred miles of air, scarcely a two thousandth part reaches the earth. A densely formed cloud must therefore detain a much larger share; and those dark and sombre forms, which sometimes make the sky so gloomy, can only result from the abundant absorption of the solar light. The brilliant whiteness which their edges occasionally exhibit, must result from the more copious transmission of light, so that the depths of shade in a cloud may be regarded as comparative measures of the varied thickness of its mass.

Sometimes the clouds absorb equally all the solar rays, in which case the sun and moon appear through them perfectly white. Instances are recorded in which the sun appeared of a pale blue. It has also been observed to be orange at its upper part, while the lower was of a brilliant red.

The position from which clouds are seen, has much to do with their colours; and it seems difficult sometimes to believe that the clouds, which in the evening are seen drenched with crimson and gold, are the same we beheld absolutely colourless in the middle of the day.

In the immediate neighbourhood of the sun the most brilliant colours may be disclosed; and their vividness and intensity diminish, and at last disappear at some distance from it. Parry noticed some white fleecy clouds, which, at the distance of fifteen or twenty degrees from the sun, reflected from their edges the most soft and tender tints of yellow, bluish green, and lake; and as the clouds advanced the colours increased gradually, until they reached a sort of limit two degrees below the solar orb. As the current continued to transport them, the vividness of colour became weakened by almost insensible degrees until the whole assemblage of tints vanished.

"Who can venture to imitate, by the pencil, the endless varieties of red and orange and yellow which the setting sun discloses, and the magical illusions which all the day diversify the vast and varied space the eye travels over in rising gradually from the horizon to the upper sky? Those who have paid any attention to colours, must be aware of the difficulty of describing the various tints and shades that appear, and which are known to amount to many thousands."

The rapid changes of colour which the clouds undergo, seem to depend on something more than change of position either in the cloud or in the sun. Forster mentions an instance of some detached cirro-cumuli being of a fine golden yellow, but in a single minute becoming deep red. On another occasion he saw the exact counterpart in a cirro-stratus, by its instantly changing from a beautiful red to a bright golden yellow. "What, indeed, can be more interesting, than when by the breaking out of the sun in gleams, a cloud which a moment before seemed only an unshapened mass devoid of all interest and beauty, is suddenly pierced by cataracts of light, and imbued with the most splendid colours, varying every instant in intensity? Numerous examples occur of this beautiful play of colour, which cannot but remind us of the phenomena displayed by the pigeon's neck and the peacock's tail, by opal and pearl.

"After the sun is set, the mild glow of his rays is still diffused over every part; and it has been remarked, that the clouds assume their brightest and most splendid colours a few minutes after it is below the horizon. It is in the finest weather that the colouring of the sky presents the most perfect examples of harmony, in tempestuous weather it being almost always inharmonious. At the time of a warm sun-setting, the whole hemisphere is influenced by the prevailing colour of the light. The snowy summits of the Alps appear about sunset of a most beautiful violet colour, approaching to light crimson or pink. It is remarkable, also, as an example of that general harmony which prevails in the material world, that the most glowing and magnificent skies occur when terrestrial objects put on their deepest and most splendid hues. It has also been observed, that it is not the change of vegetation only, which gives to the decaying charms of autumn their finest and most golden hues, but also the atmosphere and the peculiar lights and shadows which then prevail; and there can be no doubt, on the other hand, that our perception of beauty in the sky is very much influenced by the surrounding scenery. In autumn all is matured; and the rich hues of the ripened fruits and the changing foliage are rendered still more lovely by the warm haze which a fine day at that season presents. So, also, the earlier hues of spring have a transparency, and a thousand quivering lights, which in their turn harmonize with the light and flitting clouds and uncertain shadows which then prevail." {155}

[Picture: Decorative picture of lady by river]

[Picture: Foot-print of a bird, and impression of rain-drops sand-stone]



CHAPTER VII.

REMARKABLE SHOWERS—SHOWERS OF SAND—OF MUD—SHOWERS OF SULPHUR, OR YELLOW RAIN—LUMINOUS RAIN—RED RAIN, OR SHOWERS OF BLOOD—SUPERSTITIONS CONNECTED THEREWITH—EXPLANATION OF THE CAUSE—SHOWERS OF FISH—SHOWERS OF RATS—SHOWERS OF FROGS—INSECT SHOWER—SHOWERS OF VEGETABLE SUBSTANCES—MANNA—WHEAT—SHOWERS OF STONES—METEORIC STONES, OR AEROLITES—METEORIC IRON—SUPPOSITIONS RESPECTING THEM—FOSSIL RAIN.

Water, in the state of rain, hail, snow, or dew, is generally the only substance which falls from the atmosphere upon the earth. There are, however, many well authenticated instances of various substances being showered down upon the land, to the great alarm of persons who were ignorant that the powerful action of the wind was, perhaps, the chief cause of the strange visitations to which we allude.

We read of showers of sand, mud, sulphur, blood, fishes, frogs, insects, and stones; and it may be useful, as well as interesting, to quote a few examples of each description of shower.

On the west coast of Africa, between Cape Bojador and Cape Verd, and thence outwards, the land, during the dry season, consists of little else but dust or sand, which, on account of its extreme fineness, is raised into the atmosphere by the slightest current of air; while a moderate wind will convey it to so considerable a distance as even to annoy ships crossing the Atlantic. On the 14th and 15th January, 1839, the Prussian ship, Princess Louisa, being in N. lat. 24 degrees 20', and W. long. 26 degrees 42', had her sails made quite yellow by the fine sand which covered them. This effect was produced when the distance from land was as much as from 12 to 20 degrees. About a fortnight after the time when this ship crossed these parts of the Atlantic, a similar effect was produced on board the English ship Roxburgh. One of the passengers, the Rev. W. B. Clarke, says:—"The sky was overcast, and the weather thick and insufferably oppressive, though the thermometer was only 72 degrees. At 3 P.M. Feb. 4, the wind suddenly lulled into a calm; then rose from the SW. accompanied by rain, and the air appeared to be filled with dust, which affected the eyes of the passengers and crew. The weather was clear and fine, and the powder which covered the sails was of a reddish-brown colour, resembling the ashes ejected from Vesuvius; and Mr. Clarke thinks that this dust may have proceeded from the volcanic island of Fogo, one of the Cape de Verds, about forty-five miles from the place where the ship then was.

In countries which are subject to long-continued droughts the soil is frequently converted into dust, which, being carried away by the winds, leaves the land barren. The climate of Buenos Ayres, in South America, has of late years been subject to such droughts, as to disappoint the hopes of the husbandman and the breeder of cattle. In the early part of 1832, the drought had reached to such a height as to convert the whole province into one continued bleak and dreary desert. The clouds of dust raised by the winds were so dense as completely to obscure the sun at mid-day, and envelope the inhabitants in almost total darkness. When the rains at length commenced, in March, the water, in its passage through the air, intermingled so completely with the dust suspended in it, as to descend in the form of showers of mud; and, on some occasions, gave to the whole exterior of the houses the appearance of having been plastered over with earth. Many flocks of sheep were smothered on these occasions, in a similar manner as in the snow-storms which occur in the mountainous districts of Scotland.

Showers of sulphur, or yellow rain, have fallen at different times in various parts of Europe; and sometimes, when falling by night, they have appeared luminous, to the great alarm of the observers. Yellow rain has been accounted for in the following way:—The pollen, or impregnating seed-dust of the flowers of the fir, birch, juniper, and other trees, is of a yellow colour, and this pollen, by the action of the wind, is carried to a considerable distance, and descends with falling rain. This yellow rain has also been found impregnated with sulphur; and during a shower of this kind which once fell in Germany, matches were made by being dipped in it.

Many examples of luminous rain are recorded on good authority. One of the latest instances is mentioned by Dr. Morel Deville, of Paris, who on the 1st of November, 1844, at half-past eight o'clock in the evening, during a heavy fall of rain, noticed, as he was crossing the court of the College Louis-le-Grand, that the drops, on coming in contact with the ground, emitted sparks and tufts (aigrettes) of light, accompanied by a rustling and crackling noise; a smell of phosphorus having been immediately after perceptible. The phenomenon was seen three times. At the same hour a remarkable brightness was seen in the northern sky.

An officer of the Algerian army states, that during a violent storm on the 20th September, 1840, the drops of rain that fell on the beards and mustachios of the men were luminous. When the hair was wiped the appearance ceased; but was renewed the moment any fresh drops fell on it.

But of all these remarkable showers, the greatest alarm has been occasioned by red rain, or showers of blood as they have been ignorantly called. In the year 1608, considerable alarm was excited in the city of Aix and its vicinity by the appearance of large red drops upon the walls of the cemetery of the greater church, which is near the walls of the city, upon the walls of the city itself, and also upon the walls of villas, hamlets, and towns, for some miles round the city. The husbandmen are said to have been so alarmed, that they left their labour in the fields and fled for safety into the neighbouring houses; and a report was set on foot, that the appearance was produced by demons or witches shedding the blood of innocent babes. M. Peiresc, thinking this story of a bloody shower to be scarcely reconcileable with the goodness and providence of God, accidentally discovered, as he thought, the true cause of the phenomenon. He had found, some months before, a chrysalis of remarkable size and form, which he had enclosed in a box; he thought no more of it, until hearing a buzz within the box, he opened it, and perceived that the chrysalis had been changed into a beautiful butterfly, which immediately flew away, leaving at the bottom of the box a red drop of the size of a shilling. As this happened about the time when the shower was supposed to have fallen, and when multitudes of those insects were observed fluttering through the air in every direction, he concluded that the drops in question were emitted by them when they alighted upon the walls. He, therefore, examined the drops again, and remarked that they were not upon the upper surfaces of stones and buildings, as they would have been if a shower of blood had fallen from the sky, but rather in cavities and holes where insects might nestle. He also noticed that they were to be seen upon the walls of those houses only which were near the fields; and not upon the more elevated parts of them, but only up to the same moderate height at which butterflies were accustomed to flutter. This was, no doubt, the correct explanation of the phenomenon in question; for it is a curious and well-ascertained fact, that when insects are evolved from the pupa state, they always discharge some substance, which, in many butterflies, is of a red colour, resembling blood, while in several moths it is orange or whitish.

It appears, however, from the researches of M. Ehrenberg, a distinguished microscopic observer, that the appearances of blood which have at different times been observed in Arabia, Siberia, and other places, are not to be attributed to one, but to various causes. From his account, it appears that rivers have flowed suddenly with red or bloody water, without any previous rain of that colour having fallen; that lakes or stagnant-waters were suddenly or gradually coloured without previous blood-rain; that dew, rain, snow, hail, and shot-stars, occasionally fall from the air red-coloured, as blood-dew, blood-rain, and clotted blood; and, lastly, that the atmosphere is occasionally loaded with red dust, by which the rain accidentally assumes the appearance of blood-rain, in consequence of which rivers and stagnant waters assume a red colour.

The blood-red colour sometimes exhibited by pools, was first satisfactorily explained at the close of the last century. Girod Chantran, observing the water of a pond to be of a brilliant red colour, examined it with the microscope, and found that the sanguine hue resulted from the presence of innumerable animalculae, not visible to the naked eye. But, before this investigation, Linnaeus and other naturalists had shown that red infusoria were capable of giving that colour to water which, in early times, and still, we fear, in remote districts, was supposed to forebode great calamities. In the year 1815 an instance of this superstitious dread occurred in the south of Prussia. A number of red, violet, or grass-green spots were observed in a lake near Lubotin, about the end of harvest. In winter the ice was coloured in the same manner at the surface, while beneath it was colourless. The inhabitants, in great dismay, anticipated a variety of disasters from the appearance; but it fortunately happened that the celebrated chemist Klaproth, hearing of the circumstance, undertook an examination of the waters of the lake. He found them to contain an albuminous vegetable matter, with a particular colouring matter similar to indigo, produced, probably, by the decomposition of vegetables in harvest; while the change of colour from green to violet and red, he explained by the absorption of more or less oxygen. A few years ago the blood-red waters of a Siberian lake were carefully examined by M. Ehrenberg, and found to contain multitudes of infusoria, by the presence of which this remarkable appearance was accounted for. Thus it appears that both animals and vegetables are concerned in giving a peculiar tint to water. It has also been ascertained that red snow is chiefly occasioned by the presence of red animalculae.

Showers of fish and frogs are by no means uncommon, especially in India. One of these showers, which fell about twenty miles south of Calcutta, is thus noticed by an observer:—"About two o'clock, P.M., of the 20th inst., (Sept. 1839,) we had a very smart shower of rain, and with it descended a quantity of live fish, about three inches in length, and all of one kind only. They fell in a straight line on the road from my house to the tank which is about forty or fifty yards distant. Those which fell on the hard ground were, as a matter of course, killed from the fall, but those which fell where there was grass sustained no injury; and I picked up a large quantity of them, 'alive and kicking,' and let them go into my tank. The most strange thing that ever struck me in connexion with this event, was, that the fish did not fall helter skelter, everywhere, or 'here and there;' but they fell in a straight line, not more than a cubit in breadth." Another shower is said to have taken place at a village near Allahabad, in the month of May. About noon, the wind being in the west, and a few distant clouds visible, a blast of high wind came on, accompanied with so much dust as to change the tint of the atmosphere to a reddish hue. The blast appeared to extend in breadth four hundred yards, and was so violent that many large trees were blown down. When the storm had passed over, the ground, south of the village, was found to be covered with fish, not less than three or four thousand in number. They all belonged to a species well known in India, and were about a span in length. They were all dead and dry.

It would be easy to multiply these examples to almost any extent, although they are not so frequent in Great Britain. It is related in Hasted's History of Kent, that about Easter, 1666, in the parish of Stanstead, which is a considerable distance from the sea, and a place where there are no fishponds, and rather a scarcity of water, a pasture field was scattered all over with small fish, supposed to have been rained down during a thunder-storm. Several of these fish were sold publicly at Maidstone and Dartford. In the year 1830, the inhabitants of the island of Ula, in Argyleshire, after a day of very hard rain, which occurred on the 9th March, were surprised to find numbers of small herrings strewed over the fields, perfectly fresh and some of them alive. Some years ago, during a strong gale, herrings and other fish were carried from the Frith of Forth so far as Loch-Leven.

In some countries rats migrate in vast numbers from the high to the low countries; and it is recorded in the history of Norway, that a shower of these, transported by the wind, fell in an adjacent valley.

Several notices have, from time to time, been brought before the French Academy, of showers of frogs having fallen in different parts of France. Professor Pontus, of Cahors, states, that in August, 1804, while distant three leagues from Toulouse, the sky being clear, suddenly a very thick cloud covered the horizon, and thunder and lightning came on. The cloud burst over the road about sixty toises (383 feet) from the place where M. Pontus was. Two gentlemen, returning from Toulouse, were surprised by being exposed not only to a storm, but to a shower of frogs. Pontus states that he saw the young frogs on their cloaks. When the diligence in which he was travelling, arrived at the place where the storm burst, the road, and the fields alongside of it, were observed full of frogs, in three or four layers placed one above the other. The feet of the horses and the wheels of the carriage killed thousands. The diligence travelled for a quarter of an hour, at least, along this living road, the horses being at a trot.

In the "Journal de St. Petersburg," is given an account of the fall of a shower of insects during a snow-storm in Russia. "On the 17th October, 1827, there fell in the district of Rjev, in the government of Tver, a heavy shower of snow, in the space of about ten versts (nearly seven English miles), which contained the village of Pakroff and its environs. It was accompanied in its fall by a prodigious quantity of worms of a black colour, ringed, and in length about an inch and a quarter. The head of these insects was flat and shining, furnished with antennae, and the hair in the form of whiskers; while the body, from the head to about one-third of their length, resembled a band of black velvet. They had on each side three feet, by means of which they appeared to crawl very fast upon the snow, and assembled in groups about the plants and the holes in trees and buildings. Several having been exposed to the air in a vessel filled with snow, lived there till the 26th October; although, in that interval, the thermometer had fallen to eight degrees below zero. Some others which had been frozen continued alive equally long; for they were not found exactly encrusted with the ice, but they had formed round their bodies a space similar to the hollow of a tree. When they were plunged into water they swam about as if they had received no injury; but those which were carried into a warm place perished in a few minutes."

All these remarkable showers may be accounted for, when we consider the mighty power of the wind; especially that form of it which is popularly called the whirlwind. It is now pretty well ascertained, that in all, or most of the great storms which agitate the atmosphere, the wind has a circular or rotatory movement; and the same is probably the case in many of the lesser storms, in which the air is whirled upwards in a spiral curve with great velocity, carrying up any small bodies which may come within the circuit. When such a storm happens at sea, the water-spout is produced. In the deserts of Arabia, pillars of sand are formed; and, in other places various light bodies are caught up; fishponds have been entirely emptied in an instant, and the moving column, whether of water, sand, or air, travels with the wind with great swiftness. When, however, the storm has subsided, the various substances thus caught up and sustained in the air, are deposited at great distances from the place where they were first found, and thus produce these remarkable showers. In some cases, however, the direct force of the wind has actually blown small fish out of the water, and conveyed them several miles inland.

Showers of nutritious substances have been recorded on good authority. We do not here refer to the manna which fell in such abundance about the Hebrew camp, for that was a miracle specially wrought by the Almighty for the preservation of his chosen people; but, it may be noticed here, that in Arabia, a substance, called "manna," is found in great abundance on the leaves of many trees and herbs, and may be gathered and removed by the wind to a distance. A shower of this kind occurred in 1824. In 1828, a substance was exhibited at the French Academy, which fell in the plains of Persia. It was eaten, and afforded nourishment to cattle, and many other animals; and, on examination, proved to be a vegetable,—the Lichen esculentus,—which had been conveyed thither by the winds.

In the Minutes of the proceedings of the Royal Society, 26th June, 1661, we find the following curious narration:—

"Col. Tuke brought, in writing, the following brief account of the supposed rain of wheat, which was registered:—

"On the 30th of May, 1661, Mr. Henry Puckering, son to Sir Henry Puckering, of Warwick, brought some papers of seeds, resembling wheat, to the king, with a letter written by Mr. William Halyburton, dated the 27th May, from Warwick; out of which letter I have made this extract:

"'Instead of news I send you some papers of wonders. On Saturday last, it was rumoured in this town, that it rained wheat at Tuchbrooke, a village about two miles from Warwick. Whereupon some of the inhabitants of this town went thither; where they saw great quantities on the way, in the fields, and on the leads of the church, castle, and priory, and upon the hearths of the chimneys in the chambers. And Arthur Mason, coming out of Shropshire, reports, that it hath rained the like in many places of that county. God make us thankful for this miraculous blessing, &.'"

"I brought some papers of these seeds, with this letter, to the Society of Gresham College; who would not enter into any consideration of it, till they were better informed of the matter of fact. Hereupon, I entreated Mr. Henry Puckering to write to the bailiff of the town of Warwick, to the ministers and physicians, to send us an account of the matter of fact, and their opinions of it. In the bailiff's letter, dated the 3rd of June, I find this report verified; affirming that himself, with the inhabitants of the town, were in a great astonishment at this wonder. But, before the next day of our meeting, I sent for some ivy-berries, and brought them to Gresham College with some of these seeds resembling wheat; and taking off the outward pulp of the ivy-berries, we found in each of the berries four seeds; which were generally concluded by the Society to be the same with those that were supposed and believed by the common people to have been wheat that had been rained; and, that they were brought to those places, where they were found, by starlings; who, of all the birds that we know, do assemble in the greatest numbers; and do, at this time of the year, feed upon these berries; and digesting the outward pulp, they render these seeds by casting, as hawks do feathers and bones."

The remarkable showers already noticed, have excited much interest and inquiry among learned men, and many superstitious fears among the ignorant; but, there is another description of shower which affords a singular instance of popular observation, being greatly in advance of scientific knowledge. We allude to the showers of stones, called "aerolites," (from two Greek words, signifying the atmosphere, and a stone); they are also called Meteorolites, or Meteoric stones.

Writers in all ages have mentioned instances of stony bodies having been seen to fall from the sky. The Chinese and Japanese carefully note down the most striking and remarkable phenomena of nature, believing them to have some connexion with public affairs; and the chronicles of these people are said to contain many notices of the fall of stony bodies from the sky. Until within the last fifty years, however, these accounts have been treated in Europe as idle superstitions; scientific men denying even the probability of such an occurrence. The first scientific man who was bold enough to support the popular opinion, that stones actually do fall from the sky, was Chladni, a German philosopher, who published a pamphlet on the subject in 1794. This did not excite much attention, until, two years afterwards, a stone weighing fifty-six pounds was exhibited in London, which was said to have fallen in Yorkshire in the December of the preceding year; but, although the fact was attested by several respectable persons, the possibility of such an occurrence was still doubted. It was remarked, however, by Sir Joseph Banks, that this stone was very similar in appearance to one which had been sent to him from Italy, with an account of its having fallen from the clouds. In the year 1799, a number of stones were received by the Royal Society, from Benares, in the East Indies, which were also said to have fallen from the atmosphere, with a minute account of the circumstances attending the fall, which will be presently noticed; and, as these stones appeared to be precisely similar to the Yorkshire stone already noticed, attention was fairly drawn to the subject. In 1802, Mr. Howard published an analysis of a variety of these stones collected from different places; and his researches led to the important conclusion, that they are all composed of the same substances, and in nearly the same proportions. In 1803, a notice was received at Paris, of a shower of stones at L'Aigle in Normandy; and the Institute of France deputed M. Biot, a well-known and excellent natural philosopher, to examine, on the spot, all the circumstances attending this remarkable event. His account will be noticed presently; but it may here be stated, that the stones he collected, on being analysed, gave results similar to those obtained by Mr. Howard.

The circumstances attending the fall of stones at Krakhut, a village about fourteen miles from the city of Benares, are briefly as follow:—On the 19th December, 1798, a very luminous meteor was observed in the heavens, about eight o'clock in the evening, in the form of a large ball of fire; it was accompanied by a loud noise, resembling that of thunder, which was immediately followed by the sound of the fall of heavy bodies. On examining the ground, it was observed to have been newly torn up in many places; and in these were found stones of a peculiar appearance, most of which had buried themselves to the depth of six inches. At the time the meteor appeared, the sky was perfectly serene, not the smallest vestige of a cloud had been seen since the 11th of the month; nor were any observed for many days after. It was seen in the western part of the hemisphere, and was visible only a short time. The light from it was so great, as to cast a strong shadow from the bars of a window upon a dark carpet. Mr. Davis, the judge and magistrate of the district, affirmed, that in brilliancy it equalled the brightest moonlight. Both he and Mr. Erskine were induced to send persons in whom they could confide to the spot where this shower of stones is reported to have taken place, and thus obtained additional evidence of the phenomena, together with several of the stones which had penetrated about six inches into fields recently watered. Mr. Maclane, a gentleman who resided near Krakhut, presented Mr. Howard with a portion of a stone which had been brought to him the morning after its fall by the person who was on duty at his house, and through the roof of whose hut it had passed, and buried itself several inches in the floor, which was of consolidated earth. Before it was broken it must have weighed upwards of two pounds.

M. Biot's summary of the evidence collected by him respecting the great shower of stones which fell at Aigle, in Normandy, is as follows:—

"On Tuesday, 26th April, 1803, about one o'clock, P.M., the weather being serene, there was observed from Caen, Pont d'Audemer, and the environs of Alencon, Falaise, and Verneuil, a fiery globe, of a very brilliant splendour, and which moved in the atmosphere with great rapidity. Some moments after, there was heard at Aigle, and in the environs of that town, in the extent of more than thirty leagues in every direction, a violent explosion, which lasted five or six minutes. At first there were three or four reports like those of a cannon, followed by a kind of discharge which resembled the firing of musketry; after which, there was heard a dreadful rumbling, like the beating of a drum. The air was calm and the sky serene, except a few clouds, such as are frequently observed. This noise proceeded from a small cloud which had a rectangular form; the largest side being in a direction from east to west. It appeared motionless all the time that the phenomenon lasted; but the vapours of which it was composed, were projected momentarily from different sides, by the effect of successive explosions. This cloud was about half a league to the north-north-west of the town of Aigle. It was at a great elevation in the atmosphere; for, the inhabitants of two hamlets, a league distant from each other, saw it at the same time above their heads. In the whole canton over which this cloud was suspended, there was a hissing noise, like that of a stone discharged from a sling; and a great many mineral masses, exactly similar to those distinguished by the name of 'meteor-stones,' were seen to fall. The district in which these masses were projected, forms an elliptical extent of about two leagues and a half in length, and nearly one in breadth, the greatest dimension being in a direction from south-east to north-west; forming a declination of about 22 degrees. This direction, which the meteor must have followed, is exactly that of the magnetic meridian, which is a remarkable result. The greatest of these stones fell at the south-eastern extremity of the large axis of the ellipse, the middle-sized in the centre, and the smaller at the other extremity. Hence it appears, that the largest fell first, as might naturally be supposed. The largest of all those that fell, weighs seventeen pounds and a half. The smallest which I have seen, weighs about two gros, (a thousandth part of the last.) The number of all those which fell, is certainly above two or three thousand."