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trifling, from the winds, in most directious, sweeping over the land, which influences the proximate effect of their previous condition. Many other examples might illustrate the effect that surfaces over which the wind blows, have on the humidity of the atmosphere. Thus I have found, in coasting round the Morea, in summer, when the wind was from a great extent of sea, that the air was always damp. Off Navarino it was extremely so, when it blew from any other point but over the Morea. In the course of a voyage the same winds will be felt changing their hygrometrical condition with the different localities over which they travel. Off Navarino a north-west wind will be moist, while under the lee of Zante, it will be found dry. In running from Cape Angelo to the d'Oro Passage, a northerly wind has been found dry, with all the arid and bare Cyclades to windward; while, after getting through the Passage, the same wind has become excessively damp, and continued so until the Gulph of Smyrna has been made, when it again became dry,— ‹ it blowing over Mitylene, after having previously traversed an

unknown extent of terra firma.

Temperature depends not so much on surrounding localities, as on the season; while humidity is more affected by the surface over which the wind blows than by the season. Even in the latter part of summer, when the land becomes a great reverberator of heat, arising, in a considerable degree, from the decay of its verdant vegetation, the temperature of the air suffers no great change from a change of wind; yet its aqueous condition will be much affected. In calculating, then, on the dryness or moisture of the air, the point of the compass from which the wind blows is not so much to be considered as the surface, land or sea, over which it travels, and the extent of that surface, with the intervening locality if any exist. At Malta, I have observed the hygrometer stand the highest, with the wind from the north; and the lowest, with a wind varying from S. to E., in the months of July and August. From the Meteorological Table, it will be observed that the proportion of fair weather is much greater than it is in Britain; and that the rainy and showery days (which were registered rainy, when rain fell even for a few hours, and showery, if one shower happened during the twenty-four), do not amount to six weeks on an annual average for three years. It must be added, however, that the rains, when they do occur, are generally very heavy, and that the dews, in fine unclouded weather, are copious.*

Winds. From the observations of five years, I have found the prevailing winds to be from the northward; and particularly when the weather assumes a steady constitution, and the summer season has fairly set in. In the winter the winds do not appear to blow particularly from any quarter of the compass, but veer very much

• The average of rainy, snowy, and showery days in Britain, during the year, compose about one-third of the 365, as may be seen by referring to various registers.

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between the N.E. and S. In the fair weather of summer, variable and light winds mostly prevail, and in winter they are less frequent. After the hilly country in Greece is covered with snow, if the winds blow from any direction more than another, it is from the S. to S.E.; but, when the snow is dissolving in the spring, the vicissitudes ot both wind and temperature are very great. The Sirocco, at this last period, though it seldom blows long at a time, is not so warm as it is in the beginning of winter, and differs very little from a moderate breeze from any other point, in consequence of its not blowing long enough to bring on its wings the milder temperature of the south; and therefore it is moist, cold, and relaxing.

The greatest number of cases of fever which I have witnessed on board ship on this station, followed the prevalence of S.S. E., or light variable winds, in May and June, at Corfu; while, in October of the same year, when diarrhoea prevailed, the winds were northerly. At Napoli di Romania, I found cynanche and other affections of the mucous membranes particularly prevail, after keen northerly winds with a clear sky, had been preceded by occasional light Sirocco winds.

To show how localities will at times affect the temperature of the winds, in opposition to the regular effects of the season, I have found the north wind off the coast of Calabria to be hot and dry in the latter end of September; while the wind, the next day, from the S.S.E. or S.W., was excessively damp, and accompanied with a cloudy sky. This anomaly arose from the small quantity of rain that had yet fallen in Italy, not being sufficient to cool the surface of the land; while, on the other hand, this hot and dry wind had acquired much humidity from the sea, before it retrograded and was repelled by the succeeding southerly currents. The Sirocco, or S.E. wind, is an important one in any part of the Mediterranean; and different opinions have been formed as to its dryness and moisture. The fact is, that these qualities are entirely governed by the surfaces over which it blows, before reaching the place of observation. Thus it is moist and warm, as felt on the coasts of Greece and Italy, because its exalted temperature imbibes much vapour from the sea, after it leaves the northern shores of Africa, where it is hot and dry. Nowhere can such a wind be felt in the interior or the northward of Europe; for there is nowhere in Europe such a country as the Lybian and Arabian deserts, so flat, so dry, and so little capable of imparting to its winds any thing like the electric condition of the land and atmosphere of other countries.*

Electricity. This is a modifying element in the constitution of every climate; and, though less appreciated than heat or humidity,

To shew the different directions of the winds at London, from those of the Mediterranean, as registered in the table, the average winds for the year, at the metropolis, are here extracted from the British Almanac for 1828. The difference between the northerly winds is very remarkable.

N. 30 days.
N.E. 441

E. 254
S.E. 38

S. 284
S.W.721

W. 701
N.W. 541

it no doubt performs a most important part in all atmospheric changes, if it is not an essential agent in every modification of cloud, dew, and vapour. The influences of heat and humidity are much more easily defined than those of electricity; which, though in constant operation, only enables us to draw any satisfactory induction from its great and palpable phenomena. Evaporation was long thought to be a fertile source of electricity; and Pouillet has lately proved this opinion to be well founded, as well as that chemical and vegetable change is accompanied by electrical disturbance.

Of the grand phenomena of this subtle yet mighty ageut, the Mediterranean exhibits every year many conspicuous examples; and especially when the summer constitution of the weather breaks up for the season. During the winter and spring months, thunder and lightning do not often occur; but I have never observed the season to change during the decrement of temperature, without more or less of electrical phenomena taking place, and often to a frequent and great extent. In the months of August and September, when the temperature thus begins to fall, and the winds have blown from the north, and over any extent of sea, for some days, the atmosphere will become often obscured with irregularly formed clouds to leeward; the wind will next change or abate, and, during the evening and night, successive evolutions of electricity will be seen on the upper part of the newly deposited clouds, which are precipitated, one after another, from the muddy and misty atmosphere above. Rain next succeeds without thunder; and in twentyfour hours the wind will again change steadily to the northward, with a clear sky, fine weather, and a permanent fall of the thermometer. If these phenomena are witnessed on the coasts of Italy and Greece, the deposition of clouds takes place over the high lands, and the electrical transitions are accompanied with thunder and forked lightning, often exhibiting the sublimest instances of elemental commotion.

I always remarked the development of electric light to be from the upper outline of the newly precipitated strata of clouds; and where these fresh charges of electric light were successively transmitted from cloud to vapour, they, no doubt, were accompanied with much evolution of caloric, from the vapour parting with its latent or constituent heat. The direct preliminary condition of such phenomena seemed to be a wind from the sea, or from the south. Such winds as the Sirocco are always attended with imperfectly formed clouds, or a hazy atmosphere; and on the converse, I have often seen a change of wind to the south and east from the northward, completely dissolve the regular clouds, and render the air muddy and hazy. These remarkable electric phenomena will more particularly happen, if these south-east or south winds have blown

M. Pouillet, in his Memoirs read before the Academy of Sciences, on 30th May, and 4th July, 1825, has shewn that the absorption of carbonic acid by vegetables, and the evaporation of all liquids, pure or impure, are accom. panied with the development of electricity.

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for some time, and have been immediately preceded by northerly winds, or winds off the land. The reason of such phenomena not occuring at once, on a change of wind to the southward, arises, it seems, from the first of the southerly wind being only that body of the air which had lately blown from the opposite or northerly quarter, and which must precede the current of the true south, with its characteristic properties. It is for this reason, that we often found a cold southerly or south-east wind at sea, where no localities could have immediately influenced the temperature, such as at Malta and off Cape Spartinento. From this cause, also, the longer a Sirocco blows, the drier it becomes; and, in the vicinity of such elevated land as the Albanian ridge of mountains, this partial change to warmth with moisture, in the Sirocco or south wind, may be considered indicative, in the fall of the year, of a thunder storm, or the lesser electrical phenomena, with a fall of rain, and a change of wind.

It is evident, also, that besides the humidity and heat, which form a great difference between winds proceeding from the opposite points of north and south, there is something else connected with the air and the surfaces over which its currents pass, that affects the animal system in that remarkable manner which is witnessed during a Sirocco or southerly wind. On a change taking place to this direction, the inhabitants of a place, and those who have lived but a short time in it, sensibly experience a langour and relaxation of both the mental and physical energies; while diseases, depending on laxity of fibre or emunctory, become at the same time aggravated. Thus dyspeptic complaints, chronic catarrh, and cynanche, make no progress towards recovery; and if the Sirocco blows immediately after a cool northerly breeze, it often proves the cause of developing such diseases.

What this depressing something is, it may at present be premature to dogmatize about. There is an era, however to which medical science is fast hastening, when this will no doubt be explained, since the progress, which all the auxiliary sciences are making, point out to us that such a consummation will happen. To elucidate somewhat this intricate portion of our subject, we shall make the best use of the data we possess, and the observations we have made.

As far back as 1770, it was conjectured by Brydon the tourist, that what has since been called the nervous energy, must be analogous to the electric fluid; and that the nerves served for the transmission of both. He illustrated his theory by the effects produced on the animal system by the Sirocco, or winds either partially or wholly deficient of their natural electricity. By the researches of Abernethy, Phillips, Bichat, and Le Gallois, this conjecture of Brydon's has been much supported, so far as the analogy between the nervous energy and the galvanic fluid is concerned. It is well ascertained, that in damp or hazy weather none of the electric fluid can be collected; and, as the air of the Sirocco can receive no electrical impregnation, by sweeping over a dry and flat desert of sand,

so the moisture, which it acquires in its passage subsequently over the sea, must give it a strong absorbing and conducting power for electricity. The consequence is, that this moist wind, coming in contact with bodies possessed of more electricity, will rob them of part of their electric fluid, until an equilibrium is effected between the earth and the air, the grand final cause of all electrical phenomena. Now, as the human body readily parts with and receives electricity, and as an object on the surface of the earth, must be a ready point for the transmission of the fluid, it cannot be supposed that it is physically exempt from those electric influences which such winds produce on the rest of matter, but must lose a portion of the constituent fluid it previously possessed, which loss is followed by all those symptoms of depressed energy already noticed.

The animal body, then, may be deprived by the atmosphere, in a series of degrees, of that energy which, if it is not the produce of the living functions, is at least the natural portion of electricity which the body possesses in common with surrounding objects at the time. Life may even be extinguished from the highest operation of this cause, as often happens during thunder storms, when no marks of physical injury can be detected.

The different electric states of the different winds are pretty well ascertained by stationary electrometers; and, though I had none regularly in my possession, I found natural phenomena themselves to afford both excellent and beautiful proofs of this quality in the several winds. The summer of 1825 presented very satisfactory examples of the important part which the electric fluid performs in meteorological phenomena, especially when the constitution of the cloudless sky of summer began to be deranged. As this change happened on the coasts of Albania and the Morea, it commenced by the north-east winds getting stronger, and veering more about from one point to another, with corresponding variations of temperature. A calm, alternated with faint southerly breezes, succeeded, which was followed by a thick atmosphere at sunset, lightning over the Morea, and rain, after which it cleared up, and a north-west wind steadily prevailed. A few days afterwards, off the Bay of Prevesa, the northerly wind fell, the atmosphere thickened, and the wind again sprang up from the south-east, light at first, and freshed through the night. About the following sunrise, inside the Corfu Channel, one of the most terriffic thunder storms commenced that can well be imagined; which, after floods of rain, lasting, with slight intermissions, for several hours, terminated by a sudden change of wind to the northward, and soon afterwards a clear, cool atmosphere succeeded, with the wind from the north-west for some days.

Though more or less varied, the summer seasons, as I have before remarked, always break up in the above manner, and subside into a cool temperature. Whatever occasions the change of wind, whether it be from the land becoming a greater reverberator of the solar heat, arising from the decay of its verdure and foilage, and so rarefying greatly the superincumbent stratum of air, by which the

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