evaporated from the earth; as, therefore, the sun advances to wards the meridian, and for an hour or two afterwards, he dries and warms the air, and conse quently the rain is likely to cease at that time. But if there should be so much water in solution in the atmosphere, that the heat of the sun is not sufficient to produce these effects, in that case the rain will probably continue some hours longer. "Violent winds generally abate towards sun-set. "If we admit that wind is only a current of air put in motion by the rarefaction of the atmosphere in some particular place, and that this current of air is moving to wards the point of rarefaction to restore the equilibrium, we must suppose, that as the sun declines the rarefaction will diminish, and consequently the velocity of the wind decrease. But this observation, in my opinion, rather applies to the temperate than to the torrid zone; for in whirlwinds and hur ricanes the contrary may very often occur. "When the wind follows the course of the sun, it is generally attended with fair weather. This frequent and regular change of wind, which is never more than a moderate breeze, proves that there is no point of considerable rarefaction near; and, therefore, the current of air follows immediately the sun's course: it always happens in summer, but very seldom when the sun's meridian altitude is less than forty degrees. "The changes which take place in the atmosphere are principally marked by the rising and falling of the barometer, which apparently is caused by heat and cold, the hands with which nature performs her meteorological operations: b the former the atmosphere is rarefied, and consequently becomes light; by the latter it is condensed, and consequently becomes heavy. Hence probably the old remark, that a storm generally follows a calm; for during a calm the air is rarefied and expanded, and the cold air will rush forward in a strong current to restore the equilibrium, and necessarily produce what is generally called a gale of wind, the violence of which also will of course be in proportion to the degree of the preceding rarefaction. "For these reasons, the barometer falls suddenly whilst the air is expanded before a gale of wind, and rises again gradually as the condensed air returns; and the gale in like manner by degrees subsides. "It must however be observed, that an extraordinary fall of the mercury will sometimes take place in summer, previous to heavy showers of rain, particularly if attended with thunder and lightning; but in spring, autumn, and winter, the sudden extraordinary descent of the barometer indicates principally violent wind. "Upon these principles likewise we may account for the rise and fall of the barometer in the different zones. In the torrid zone, particularly at St. Helena and the islands of the Pacific Ocean, it seldom varies more than three-tenths; at Madras about five-tenths; in the south of Europe not more than one-inch and two-tenths; in England it varies two inches and a half, and in Petersburg three inches four-tenths. In the two first the temperature of the atmosphere i not subject to much variation, and never to any great degree of con densation, densation. In the third, reckoning from the tropics to the latitude of forty, the atmosphere may sometimes be suddenly condensed by currents of cold air from the north, and still more so in England. But the greatest variation must necessarily take place on the continent to the northward, where, during the summer, the weather is as hot as within the tropics; and, in winter, the thermometer, for many weeks, continues several degrees below the freezing point. "The thermometer also, which measures the degree of heat in the air near the earth, will contribute towards denoting when changes are likely to take place in the lower regions of the atmosphere; the hygrometer distinguishes the quantity of moisture in the atmosphere, and the electrometer will point out the quantity of electricity which prevails in it. "The words generally engraven on the plates of the barometer rather serve to mislead than to inform, for the changes of the weather depend rather on the rising and falling of the mercury, than on its standing at any particular height. When the mercury is as high as fair, or at thirty degrees, and the surface of it is concave, beginning to descend, it very often rains; and on the contrary, when even the mercury is at twenty-nine degrees, opposite to rain, when the surface of it is convex, beginning to rise, fair weather may be expected. These circumstances not being known, or not duly attended to, is the principal cause that farmers and others have not a proper confidence in this instru ment. "It must also be observed that, cæteris paribus, the mercury is higher in cold than in warm weather, and 1801. commonly early in the morning, or late in the evening, than at noon, which seems occasioned by the ob vious causes of the atmosphere being condensed by the cold of the night, and rarefied by the heat of the day. "The following observations of Mr. Patrick seem confirmed by experience. 1. The rising of the mercury presages, in general, fair weather, and its falling foul weather, as rain, snow, high winds, and storms. 2. In very hot weather the fall of the mercury indicates thunder. 3. In winter the rising presages frost; and in frosty weather, if the mercury falls three or four divisions, there will certainly follow a thaw; but in a continued frost, if the mercury rises, it will certainly snow. "4. When foul weather happens soon after the falling of the mercury, expect but little of it; and, fair weather when it proves fair on the contrary, expect but little shortly after the risen. mercury has "5. In foul weather, when the mercury rises much and high, and so continues for two or three days before the foul weather is quite over, then expect a continuance of fair weather to follow. "6. In fair weather, when the mercury falls much and low, and thus continues for two or three days before the rain comes on, then expect a great deal of wet, and probably high winds. "7. The unsettled motion of the mercury denotes uncertain and changeable weather. "But to these remarks added, that, when the barometer may be suddenly falls two or three tenths, without any material alteration in K the the thermometer, and the hygrometer is not much turned towards moist, a violent gale of wind may be expected. When the hygrometer inclines far towards moist, with only a trifling descent in the barometer, it denotes a passing shower and little wind; and when the barometer falls considerably, and the hygrometer turns much towards moist, the thermometer remaining stationary, and rather inclined to rise than fall, both violent wind and rain are likely to follow in the course of a few hours. "General or common Prognostics of the Weather. Amongst these we may reckon such as are derived from birds, beasts, insects, reptiles, and plants; to which might be added great part of the wood-work in houses, as doors, windows, window-shutters, &c. "Birds in general retain in the quill-part of their feathers a quantity of oil; which, when they feel an extraordinary degree of moisture in the atmosphere, they express, by means of their bills, and distribute it over their feathers, to secure their bodies against the effects of an approaching shower. "Swallows, in pursuit of the flies and insects on which they prey, keep near the earth in wet weather; and in dry weather, from the same cause, they fly much higher. "Domestic animals, as cows and sheep, but particularly the latter, on the approach of rain, feed with great avidity in the open field, and retire near the trees and hedges as soon as they are satisfied. In fine weather they graze and lounge about, eating and resting alternately with apparent indifference. "The pimpernel, commonly called peep-a-day, or, shepherd's weather-glass, closes its leaves before rain; and the down of the dandelion is much affected by moisture. "All wood, even the hardest and most solid, swells in moist weather. The vapours insinuate themselves into the pores of trees, and also into the wood-work of houses. "Insects and reptiles of all kinds seek or avoid rain according to their respective habits, by these means giving notice of every change of weather. "It is a well-known fact, that before rain, particularly in summer, a strong smell is perceived from drains and common sewers, as well as from every other body emitting a great quantity of effluvia. During fair weather, even in summer, the atmosphere readily absorbs all the vapours and exhalations from the earth until it is completely saturated, and consequently the effluvia from the bodies which emit them will then be confined and ascend in a narrow compass, like the smoke of a chimney in dry weather, almost perpendicularly; but when the air is saturated with moisture, and becomes rarefied and expanded, as it always does before rain, the volume of air containing the effluvia will be extended horizontally, and diverge from these different bodies as from a centre, and will be sensibly perceived on all sides, but will of course be most perceptible on that to which the current of air or wind moves. "In winter, when the thermometer is between thirty-four and forty degrees, the air being in a state of condensation, and the running water being warmer than the land, a mist or fog may be seen rising above the river, particularly when the air is cold and clear; but this BLIGHT On BLIGHTS. [From the same Work.] LIGHTS are diseases in cident to plants, but affecting them variously. In some the leaves only are withered, in others the leaves and blossoms; some do not lose much either of their colour or shape, others again seem shrivelled or scorched, and very soon entirely perish. Some Some persons suppose, that blights come from the eastward, and others from the westward; and by many it is believed that they are frosts which descend from the upper regions of the atmosphere. Insects are often found on the trees which have suffered from blights, whence it is also imagined that some kinds of blights proceed from immense number of insects, which are bred in particular places, and are transported by the winds towards the plants which they destroy. "Experience confirms the exist ence of almost all these different blights. We will offer a few conjectures on the subject, and attempt to explain from what causes they are derived. "In the spring vegetation commences, and frequently in the month of April the peach and nectarine trees are in blossom. About the same time, the earth being warmed by the return of the sun, the current of air will come in strong gusts from the ocean, and produce those winds, which are generally known by the name of the equinoxial gales. The blossoms of those fruit-trees, therefore, which are not sheltered towards the westward, will be blown off before the fruit is formed, and produce those blights which affect the blossoms and not the leaves. But the current of air which comes from the eastward about the same season, being excessively dry, absorbs all the moisture, both on the leaves and fruit, and produces that parching kind of blight which curls up the leaves and destroys the fruit, and sometimes kills the trees themselves. When the leaves are parched, and the texture of them is broken, the perspirable matter becomes viscous, and by adhering to the leaves affords both shelter and nutriment to insects. When the young are hatched, they begin to prey upon the leaves, and if they are not removed in due time will ultimately destroy the trees. I was led to make these reflexions from observations made in my own garden for seven years successively. On the north side of it is a stone wall, coped with brick, of one hundred and thirty yards in length and twelve feet high Against this wall are planted eighteen peach and nectarine trees, one Cressan pear, and two or three small vines, kept very closely pruned. The trees are planted in a border of four feet in breadth, on a soil of loam and black earth, of about twenty inches depth, on a gravel. The soil is nearly the same as the rest of the gardens in the valley near Cardiff. The wall is built of the same materials, of the same height, and its aspect corresponds nearly with that of other gardens, being about S. by W. or S. S. W.; and the trees are pruned by the same person who works for many other families in the neighbourhood. Nevertheless, when their trees entirely fail, these have borne regularly every year four times as much fruit as we choose to leave on the trees to ripen; and the fruit, so abundant, has likewise been of the best quality. The trees are about fourteen years old, and consist of the Magdalene, Rambouilet, Royal George, and Newington peaches, and the Brignon, Etronge, Murray, and Roman nectarines. It may be proper to observe, that no manure is used to these trees, but every year a small quantity of pure virgin earth is put on the border, which is also dug in a good spade deep, both in spring and both which my wall is sheltered, I am much disposed to conclude, that the blights from which they suffer are to be ascribed to those causes. "It sometimes happens that the nectarine-trees have been slightly attacked by a blight, and the peaches have escaped, though planted alternately with the latter 'on the same wall. As the blight parched and curled the leaves, I suppose that it came from the east in the manner above described; and it is probable, that this current of air attacked the leaves of the nectarines without injuring the peaches, on account of the superior delicacy of the leaves of the former, or perhaps from their being more porous, and suffering more from evaporation. This blight, however, has only once occurred; these remarks, therefore, are intended as mere suggestions or hints on the subject. If the nectarines should frequently suffer, and the peaches never, it may probably be ascribed to the different qualities of their leaves; but if the contrary should happen, we must then refer to some other cause. "A wall with a projecting coping is supposed to be favourable to fruit-trees, in protecting their leaves and blossoms from the descent of cold dews, which early in the spring are accompanied with frost; but this plan does not seem to me entirely free from objection; at least it appears necessary to have this a moveable fence, for when the danger of the frost is over, the descent of the dews are necessary, to refresh the trees and swell the fruit, which will never come to perfection from being artificially watered. Besides in hot dry weather the expense of labour for this kind of work would be |