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PHILOSOPHICAL PAPERS.

METEOROLOGICAL OBSERVATIONS, applicable to PRIVATE and DOMESTIC PURPOSES in GREAT-BRITAIN.

[From CAPPER'S OBSERVATIONS on the WINDS and MONSOONS.]

"THE

HE tables in the Philoso phical Transactions, those of bishop Watson, Dr. Robertson, and major Hayman Rooke, all tend to prove, that the rainy season of these islands commences in June, and continues for the two or three subsequent months; and that the greatest quantity of rain falls almost invariably in the month of July. This is the fact; let us consider what use may be derived from it by the farmer.

In the neighbourhood of London, from the great command of manure and the goodness of the roads, the farmer is able to bring forward his grass, and to mow it sometimes at the beginning of June, and always by the end of the month; thus he completely finishes his hay harvest before the summer solstice; the solsticial rains therefore which follow, but seldom commence before this time, are extremely beneficial to him: they bring forward the aftermath, they swell the corn and increase the length of the straw; and having finished one harvest the farmer is completely prepared for the other. But it is only within a few years,

that agriculture was in such an improved state, even near the capital, as to admit of an carly hay harvest; and I am sorry to say, that nine years in ten at least, in the highly gifted county of Glamorgan, even at the present day, the hay is regularly spoiled in making. But let not this circumstance be considered as reflecting upon the farmers of that country, who are far from deficient either in industry or a competent knowledge of their business. Their country, possessing every possible natural advantage, has not, until lately, had any good turnpike roads; manure was to be had only in small quantities; the little there was it became difficult and expensive to put on the land, and consequently they could not bring for ward their grass to be cut before the middle of July. The rains, therefore, so beneficial to the London farmer were hurtful to them; but as it happened almost every year, they patiently submitted to what they considered irremediable; for being situated near the sea, they supposed it the natural consequence of their climate and soil,

"But

"But turnpike roads being now made throughout the country, and safe, expeditious, and cheap conveyances being opened, by means of the canals, from the interior of the country to the sea, and labourers of every description resorting in great numbers to the hills, where they are employed to work the mines of iron, lime, and coal, the produce of the country will in future be consumed on the spot, and necessarily increase the quantity of manure. In the course of a few years, then, the valleys at least will come into a high state of cultivation, and both the hay and corn harvests in Glamorganshire will be as early and productive as those of any other county of Great-Britain. The experienced farmer would not thank me for any remarks on the great advantages to be derived from having fodder of a superior quality for his horses, cattle, and sheep.

"As the solsticial rains are always accompanied with westerly and south-westerly winds, the mariner will readily comprehend, that this season is unfavourable for ships outward bound to the West Indies and America, and consequently the reverse for those which are homeward bound from those countries.

"It is usual for English travellers to fix the middle of July for their summer excursions, but they must constantly expect to be interrupted by heavy showers of rain. To one class of them however this circumstance may be considered as an advantage: it has lately been the fashion to visit Wales, and, amidst its wild romantic scenery, the waterfalls are in the height of their beauty at this season.

"The next meteorological general fact worthy of observation is, that frequent violent gales of wind hap

*

pen soon after the autumnal equinox. Without dwelling much on the advantages of these high winds, which are known to strip the trees of their leaves, and are said to contribute greatly, by the agitation of them, to the fall of the sap, I shall beg leave to observe, that the little summer of St. Martin, which follows these gales, and is probably the effect of them, continues from the beginning to the 22d of No vember. This interval of clear weather is particularly useful to the farmer and the gardener; to the former in ploughing and sowing winter and summer fallows, to the latter in pruning and dressing his trees after the fall of the leaf, and when the return of the sap is completed.

"As to the winter, it is well known that little is to be done in the country at this time, except the carrying of manure; but it is important both to the farmer and gardener to remember, that the hard weather seldom begins before Christmas, and in very severe winters a hard frost is generally preceded or accompanied, in the early part of it, by a heavy fall of snow. Thus secured, the wheat and herbage of every kind is safe from external cold; for snow being a non-conductor of heat, the internal warmth of the earth, which at all seasons is equal at least to 48 degrees of Fahrenheit's thermometer, rises, and is retained near the surface; and when the thaw takes place, vegetation, having been preserved under this excellent covering of the sheet of snow, is found to be in a very advanced and improved state.

"The mariner at this inclement season will seldom go to sea if he can avoid it; but voyages to the West Indies may be undertaken in

the

the winter, provided there is a good outset from the channel by the help of easterly or north-easterly winds. As the spring approaches, the easterly winds commence: the March winds and April showers, says the honest countryman, bring forth May flowers; and it is supposed, that the motion of the trees at the vernal equinox contributes to raise the sap and develop nature, which seems to have been in a state of torpor or necessary repose during the winter. The prudent farmer avails himself of these winds also to sow his oats, barley, pease, beans, potatoes, &c. The drying quality of these winds, on which I have already pretty fully expatiated, takes from the earth what would otherwise be a superabundant degree of moisture on the surface of it. "At this season, likewise, the British mariner becomes particularly active. He may undertake his voyages to all countries situated to the southward of these islands; and if bound to the East Indies in particular, he may perform the voyage almost to a certainty in less than four months. The N. É. winds being favourable for ships outward bound, they are of course adverse to those that are homeward bound; therefore it would be prudent to postpone, if possible, entrance into the channel to the end of May, or the beginning of June.

"In short, the spring is the most favourable season for outwardbound ships, and the summer for those returning home. In the autumn the winds generally incline to the W. but rather towards the N. than the S.; and in winter they are often from the N. E. but the heavier gales of wind almost always come from the N. W.

"After having pointed out to the farmer and gardener, the mariner

and the traveller, the winds which prevail at different seasons of the year, and which, in examining several meteorological registers kept in Great-Britain for upwards of fifty years, I have found to be almost as periodical as those in the tropics, I shall proceed to a further application of this hypothesis to domestic purposes.

"Itappears that in these islands the W. and S. W. winds prevail threefourths of the year, and the E. and N. E. only one-fourth. In all parts of Great-Britain the S. W. is esteemed the most rainy point of the compass.

"In building houses, granaries, or storehouses of any kind, therefore, in all parts of Great-Britain and Ireland, great care should be taken not to place buildings to the E. or N. E. of any lake or standing pool of water, but particularly of marshes or fens; and where a choice is permitted, it would perhaps be prudent to erect our habitations to the W. and S. W. of every river and canal; for if situated to the eastward of them, according to this hypothesis, the wind will blow upon the buildings three-fourths of the year, bringing with it the additional moisture of the river or canal, and consequently will render it damp and unwholesome; whereas if placed westward of these sources of moisture, the air from the eastward, which is rather too dry, in passing over large bodies of water, will absorb a certain quantity of the moisture in solution in the atmosphere, and the dampness of it of course will be by these means in some degree diminished: but at all events, as the wind blows from the eastward three months of the year only, a house thus situated will be less damp than one placed to the westward, exactly in proportion to

the

the difference of time each different wind blows, that is, as three to nine; and for this reason every person should recoilect that the W. and S. W. sides of a house are always the most damp.

"It seems needless to expatiate on the necessity of applying these observations in particular to situations near marshes or fens. The fatal consequences of the exhalations from these places are very well known; and therefore I shall content myself with having pointed out to those, who are unavoidably obliged to live near them, the most effectual means of partly avoiding their effects. If any persons can for a moment entertain a doubt of their baneful influence, I must beg leave to refer them to the first book of the classical and elegant poem on health by the learned and ingenious Dr. Armstrong, whose salutary advice I shall not attempt to disguise in the tame language of prose; nor would I wish, by a partial quotation, to deprive the reader of the pleasure of gratifying himself by a general reference to the original.

"Although our atmosphere in particular places is impregnated with noxious vapours, fortunately for the inhabitants of these island's they are not subject to the baneful influence of poisonous winds; nor can they scarcely consider themselves exposed to the ravages of hurricanes. The tempests, which 'sometimes are known in our temperate climate, can scarcely be deemed more than storms, especially when compared with those in the tropic. But a brief recapitulation of the fundamental principles of our theory will best distinguish the names and characters of every kind of wind.

"All winds are supposed to be

produced by the joint effects of rarefaction and condensation. These two principles acting near the middle of the South Atlantic, the Pa cific, or any other wide expanse of ocean unbroken by land, will produce two currents of air, one from the E. following the course of the sun, and another nearly N. or S. from the frozen regions near the pole. These two currents of air moving through nearly an equal space, and nearly with equal velocity, over a surface of equal temperature, at length unite, and form a N. E. and S. E. perennial, commonly called a trade wind.

"Where a considerabie body of land intervenes, particularly in the tropics, new points of rarefaction and condensation take place, suffi« ciently powerful to counteract the former more remote, and therefore more feeble causes; and thus the monsoon, or any other periodical wind, will be formed.

"But in high latitudes, near extesnive tracts of both sea and land, where the points of rarefaction and condensation are more irregular but moderate, and the changes of temperature much more frequent, the winds in those parts of the globe will necessarily become more variable, and also less violent.

"But perhaps it will be asked, by what means opposite currents of air are observed in the same place? or, in common lauguage, while the wind blows one way, why the clouds apparently move another? The term wind, mentioned as something distinct from the current of air in this question, is, I believe, the cause of all the doubts and perplexities, and very often in this inquiry misleads even experienced philosophers themselves. For my own part, I feel little doubt that these opposite cur

rents

rents of air are imputable to electrical agency, as they almost always precede thunder-storms; for when a considerable portion of the atmosphere in the upper regions is rarefied by means either of electrical or common fire, the surrounding bodies of air will suddenly rush towards the point of rarefaction to

fill up the vacuum. But when all the phenomena of electricity, and the various causes of heat, are perfectly known, it will, I doubt not, he as easy to calculate and predict the course and strength of winds, as it now is to foretel the flux and reflux of the tides, and the regularreturn of eclipses."

General METEOROLOGICAL OBSERVATIONS made in ENGLAND.

[From the Same.]

HOSE who are furnished

and who carefully observe the information they afford, will not often be mistaken in their judgment of the changes of the weather. The barometer, the thermometer, the hygrometer, and the electrometer, will generally give us timely notice of any material change in the state of the atmosphere. But before we consider the best, or at least the usual modes of employing these instruments, we will beg leave to mention some common remarks of the peasantry, whose professions requiring them to live much in the open air, their opinions merit very great attention, being the result of local observation, continued from father to son, and verified from the experience of many ages. Amongst the first of these is one, now established into a proverb, that a rainbow in the morning is the shepherd's warning, but the rainbow at night is the shepherd's delight.

"In a country with the sea or ocean to the westward, and the wind from the same quarter, this opinion is likely to be true; for at least nine-tenths of the rain in a country so situated would come

from that side. If, therefore, the

morning are saturated with moisture, which they must be to produce a rainbow, as these clouds proceed from the west towards the east, they probably will produce rain; whereas, on the contrary, when the sun sets perfectly clear, and the clouds to the castward are moist, it is a proof that the wet clouds are past, with a westerly wind, and the shepherd therefore may reasonably expect fine weather on the following day.

"When it rains with an cast wind, it probably will rain for twenty-four hours. This is another observation, which seems to me applicable to countries situated as above mentioned, with land to the eastward; for in general the weather is dry in these countries with an east wind, but when the cohesion of the air and water is broken, the rain will not be violent, but of long duration.

"The weather generally clears at noon; but when it rains at midday, it seldom clears up again till sun-set. The air, when dry and warm, continues to absorb and retain the moisture continually evaporated

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