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HAIL-STORMS IN FRANCE. Sales contributes a pretty full study upon certain hailstorms which visited France in June and July, 1874, of which that which occurred on the 28th of July was especially remarkable. Two occurred on the 26th of June, covering quite distinct sections of country, between which there seemed good reason to believe that some connection existed, although its exact nature is not indicated by the theory. Very curious are the isolated points observed by him at which hail fell apparently without any connection with other more extensive hail-storms occurring at a distance. The principal object of his inquiry has been the connection between hailstorms and altitude above the ocean. In general the hail begins in the valleys, and rarely is observed at stations more than one thousand feet above the sea; which limit seems to offer insuperable obstacles to its formation in France, although not in America, where the heaviest hail-storms occur at higher altitudes.—Mem. Acad. des Sciences, Toulouse, 1875, 285.
RED SNOW ON THE PIC-DU-MIDI. The establishment by the United States of meteorological observatories on Mount Washington and Pike's Peak seems to have stimulated the action of other meteorological offices in the same direction. Thus, in France, the observatory on the summit of Pic-du-Midi has formed quite an epoch in meteorological study. A number of interesting results, drawn from the first year's observations, are presented to the Academy of Sciences of Toulouse by Dr. Armieux, who specially calls attention to the hypsometric results, and to the peculiarly interesting phenomena of red snow.
After a short historical survey of our knowledge of the red snow to which he himself had previously contributed somewhat in his article “ Topography of the Sahara,” published at Algiers in 1865, he shows that the presence of red snow on the Pyrenees has been established beyond doubt. It has therefore thus far been observed both here and also in the Alps, Spitzbergen, Greenland, and New Shetland, and in the antarctic zone, to which we may also add an occasional record of its appearance in North America. From the draw
ings and description of the red coloring particles as seen under the microscope of Dr. Armieux, it is evident that with the red particles are mixed occasionally green ones; and the cryptogamous nature of the substance is placed beyond a doubt.
The explorers in the Swedish North Pole expedition have seen marine algæ growing and fruiting at a temperature far below zero, while at higher temperatures the spores completely disappeared. There are therefore some vegetables which can only live in intense cold and continuous dryness ; and to these the cryptogams of the red snow must be nearly allied. Many of the figures observed by Armieux bear close analogy, he states, to those figured by Cohn in his beautiful memoir published at Breslau in 1872; whence he concludes an intimate relation between the Protoccocus nivalis and the Protoccocus pluvialis.--Mém. Acad. des Sciences de Toulouse, 1875,195.
THE WINDS AND RAINS OF INDIA, A valuable memoir on the winds of Northern India, presented by Henry Blanford, of Calcutta, to the Royal Society of London, has recently come to hand, in which this subject is treated of in the fullest and most admirable manner. He first describes the general scheme of the wind system of Northern India, in which he shows that it is very different from that of the adjacent seas. Instead of two monsoons from northeast and southwest prevailing alternately during about equal periods of the year, we find a great diversity of prevalent wind currents depending upon the direction of the mountain ranges and of the great valley plains; and with respect to period to be classified under three rather than two distinct seasons, excepting, indeed, in Upper Assam, where the normal monsoons prevail. In the cold weather months, from November to January, the wind appears to flow in a gentle current from a distinct source in the hilly regions southward, down the valleys of the Indus and Ganges, or across the water-shed of Central India. In hot weather the winds draw around to the westward, and dry currents radiate out over the whole region, and, becoming heated, form the well-known hot winds of April and May. These winds, however, are essentially diurnal winds. In June
the southwest monsoon sets in on both coasts of the peninsula.
The relation of the winds to temperature, humidity, and barometric pressure is most carefully presented in detail. In a general summary he states that the northeast monsoon of the Indian seas is produced by the cooling and condensation of a comparatively calm atmosphere over the land surface of India. Its origin is in the plains of the Punjab, and Upper and Central India and Assam, probably also on the southern slopes of the Himalaya. These wind currents are fed by an upper current which he terms the anti-monsoon, of which he traces two distinct branches.
The double system of upper and lower currents is presented by him in admirably constructed charts, on which both are shown in their proper relations to each other. The southwest monsoon is produced by the heating of the land surface of the peninsula. As the heat increases the pressure falls steadily, and the sea winds are drawn from a greater distance south. At length, in general, the ridge of high pressure over the sea, which has been steadily receding southward since February, is obliterated, and the southeast trade, or perhaps only a portion of it, crossing the equator, brings the monsoon rains to Bengal and the western coast of India. Phil. Trans. Royal Soc. of London, CLXIV., 363.
ORIGIN OF CYCLONES. The origin of the cyclones of the Bay of Bengal has been studied by Blanford, of Calcutta, who concludes that they are not necessarily produced by two parallel currents blowing in opposite directions, but rather that a calm state of atmosphere, or one in which the winds are light and variable over an open sea, is a condition favorable to the formation of these storms; and that a second condition is high or moderately high temperature. In consequence of this collocation, a large quantity of vapor is produced, ascends into the atmosphere and is condensed, with a liberation of its latent heat over the place of its production instead of being carried to some distant region. The atmospheric pressure is thus locally lowered, tending to cause an indraft of air. The formation of cyclones is, then, finally determined by an inrush of a saturated storm-current of air from the southwest or
west-southwest. This latter feature may possibly be one peculiar to the northwest portion of the Bay of Bengal; and Blanford especially guards himself against being supposed to extend these views to the case of any other area than that which he has especially dealt with.-Phil. Trans. Royal Soc. of London, CLXIV., 563.
A correspondent in Oregon, Missouri, states: “When the earth has become dry, parched, and very warm, I have often, on the occasion of thunder-storms, noticed for hours, while it was thundering very hard, a mist falling from the storm-clouds, and roll back, after nearly reaching the earth, in the form of lighter vapor. I think this rain or mist in falling passed down to the stratum of very hot air on the earth's surface, and became a steam; large volumes of white vapor, forming suddenly, and rolling back and up. Now I am confident that if the earth had been shaded by trees this rain or mist would have fallen on the ground. This phenomenon can be seen here every hot, dry season. My attention was called to it by a question asked while one of these dry thunder-storms was prevailing - the thunder rattling overhead, and not a drop of rain falling. The white mist is not easily observed overhead, where all is light, but opposite the sun under a dark storm-cloud it is very plain, and must attract attention,”- Appleton's Popular Science Monthly, IX., 765.
TEMPERATURE OBSERVATIONS IN ITALY.
The distribution of temperature in Italy is the subject of an elaborate memoir by Ragona, as published in the supplement to the Italian Meteorology for 1876.
Starting with the annual movement of the sun, Ragona passes to the remarkable formulæ that have been published by Liaias, Schmidt, Waltershausen, and others, by means of which the distribution of temperature over the whole earth is represented in a very conspicuous manner. The still more remarkable work of Forbes on this subject seems to have been unknown to him. The detailed study of temperature at Modena from the observations of ten years afforded him an opportunity to make many interesting connections between
temperature and other correlated phenomena, as, for instance, the appearance of the auroras of the 4th of February, 1872, and the 4th of February, 1874.-Meteorol. Ital., App., 1875.
RAINFALL, WINDS, AND PRESSURE IN ITALY. The distribution of rain in Italy for the years 1871 and 1872 is the subject of an elaborate memoir by Denza, in which, after a careful discussion of actual observations of rainfall and evaporation over the whole of Italy, he considers the theoretical question of the cause of the peculiarities of the distribution of rain in Italy in general, and especially in 1872, and has elucidated the distribution of the winds in Italy. De adds to the memoir on rainfall one on the distribution of barometric pressure, as shown by the averages of 1870 to 1875.--Meteorologia Italiana, Supplement, 1875, 41.
TIB BORA OF SOUTHERN RUSSIA. Baron Wrangell has written a very interesting paper on the causes of the Bora, or northerly gales, at Noworossisk. This place, situated on the Black Sea, would, it is said, have the finest harbor in the East, were it not for its exposure to the strong north winds. According to Wrangell, this wind gains most of its force in that locality from the fact that it is a cold wind flowing down the mountain-sides; and as we can not prevent cold dry air from becoming colder by radiation under a clear sky, he proposes to diminish the violence of the wind by cutting a passage through a spur of the mountain in such a way as to relieve the mass of air behind from any confinement whatever, so that the moment a slight increase of density takes place that air will flow away quietly through the artificial valley. The approximate formula deduced by him for computing the velocity of the wind, when the temperature of the air and the barometric pressure are given, is derived from an ingenious course of reasoning, and gives a close approximation to the observed true velocity.- Wild's Repertorium, 1875.
FREQUENCY OF THUNDER-STORMS IN EUROPE. An investigation into the frequency of thunder-storms dur. ing the summer months in Europe has been made by Von