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gradient than the sonth and west winds in order to acquire the same velocity. The law ordinarily called Buys-Ballot's was first demonstrated in 1853 by J. W. Coffin, and was expressed substantially as follows: The winds are inclined at an angle of 65° to the direction of the lowest pressure.
C. de Seul contributes to meteorology, as his magister dissertation, the results of most laborious toil, viz., the monthly, seasonal, and annual wind-roses for six stations in Southern Norway, and for the six climatic elements, viz., pressure, temperature, absolute and relative humidity, cloudiness, and wind-force. The scientific value of the work is highly spoken of by Mohn.
In Brault's “ Circulation Amosphérique de l'Atlantique Nord"--a work of great labor, and apparently a worthy continuation of those studies that were begun by Maury, and to which Buys-Ballot, Buchan, Hoffmeyer, Brito de Capello, Cornelissen, and Scott have of late years made so many contributions-Brault has taken an important step in that he has undertaken to classify his 200,000 observations of the wind according to the force as well as according to the direction. Besides the excellent charts and the ninety pages giving in detail the data on which the charts are based, the author gives an interesting sketch of the actual state of the works in nautical meteorology that were begun in 1869 under the administration of Admiral De Genouilly, whence it appears that from the journals kept by French vessels the French Hydrographic Office has compiled a large number of charts and tables, which will, it is hoped, soon be published. A glowing tribute is paid by him to the importance of such simultaneous observations as the Signal Service is now receiving from all seas and lands. Brault's charts give not only the relative frequency of winds from each point of the compass, but also the probability of strong and light winds and calms, and furthermore the probable changes or order of succession of the successive winds; they are thus peculiarly adapted to the needs of the mariner, and are undoubtedly an improvement upon the charts that have hitherto been published at Washington, London, and Utrecht.
The position and phenomena of the equatorial calm-belt have been studied by Mühry with the help of the charts of the London Meteorological Office. He finds that the lowest
pressure agrees with the belt of highest temperature. The diurnal barometric period is well marked, and is, he thinks, evidently of telluric, not local origin. The trade-winds are, he thinks, evidently not the cause of the equatorial ocean currents, because the latter increase as the former diminish near the equator. The region of heaviest and most frequent rain is permanently about 5° north of the equator.
Two papers have been published in the Austrian meteorological journal by Guldberg and Mohn, in which the authors have rehearsed some of the views presented by them a year ago in their “ Études.” They deduce the angle of deviation of the winds from the line of steepest gradient as dependent on the geographical latitude and the coefficient of friction, and give in tabular form its value for different values of these fundamental quantities. Their method of determining the coefficient of friction and other resistances for each station is worthy of general application ; in the cases computed by them for stations in England a very considerable difference is found for southwest and northeast winds. The observed wind velocities on sea agree closely with the theoretical, but those on land fall far below. The velocity at an altitude of 100 meters is but one per cent. greater than that at the surface of the ground, and for the determination of the coefficient of friction it is best to use only the relative directions of the wind and isobars.
Dr. Carl Benomi, in “Der Einfluss der Axendrehung der Erde" (Petermann, Mittheil., 1877), gives a short reference to the history of this problem, and then takes a backward step in maintaining that east and west winds are not influenced by the earth’s rotation. His essay is mostly confined to a consideration of the winds of aspiration and propulsion as defined by Mühry. Benoni commits the singular mistake of attributing to Dove that law which was known to Laplace, but was enunciated by Poisson, 1837; Foucault, 1851; Bénet, 1851; Babinet, 1854; Ferrel, 1854 and1859; and by numerous authors since then, according to all whom, in our northern hemisphere, a body moving in any direction whatever deflects or tends to deflect to the right. This law is based on the principle of the conservation of areas, and differs essentially from the principle first enunciated by Hadley, and adopted by Taylor, Herschel, Dove, Colding, Maury, Peslin, Benomi,
and others, according to whom bodies moving on the parallels do not deviate to the east or west. This fundamental theorem in the dynamics of the atmosphere was abundantly elucidated in the discussion that was from 1851 to 1860 fully reported in the Paris Comptes Rendus. The more general law known as Poisson's in France, and in America as Ferrel's, was applied to the winds of the globe by Babinet, 1854, and simultaneously by Ferrel, whose complete memoir marks an important epoch in the development of meteorological science. A very complete review of the literature of this subject, so far as it relates to Baer's Law, is given by Benomi and Schmidt in the Vienna Geog. Mitth.
It is said that M. Finger, in a memoir on the mathematical theory of the motions of the atmosphere, has demonstrated among other things that the pressure is increased by easterly winds and diminished by westerly winds.
This latter scientist has enriched meteorology with a memoir, which is substantially a second edition of his famous paper of 1859, on the motions of the winds on the surface of the earth. This latter paper was too little known among European meteorologists until reviewed by Hann, a year ago, in the Zeitschrift of the Austrian Meteorological Society. The present writer, however, in 1865, and especially in 1869, had drawn the attention of certain individuals to this important memoir, and in 1871 quoted it quite freely in the pamphlet of" Suggestions on the Use of Weather Maps” (published by the Army Signal Office, 1st edition, May, 1871); while, in the meantime, Professor Everett, in his translation of Deschanel's Philosophy, had spoken of it in terms of highest praise. In fact, the fundamental problems of deductive meteorology were, for the first time, solved satisfactorily in this first edition. Professor Ferrel has simply revised his work in the light of the great mass of accurate data that have within twenty years been accumulated by the meteorological writers. The most important new features of the work consist in, (1) the formula for variation of pressure with altitude when the air is in motion; (2) the expression for the gradient of inclination of any current of water or air in a section at right angles to its course; (3) a table of mean temperatures over the whole earth, deduced by combining the best modern authorities; tables for January, July, and
the year are given, and the latter is condensed into a mean for each parallel of latitude, whence is deduced the following formula in centigrade degrees: t=8.50° -1.75° cos. 0-20.95° cos. 20-1.00° cos. 30–2.66° cos. 40
(where 0 is the the north polar distance); whence, by integration, there results the mean temperature of the surface of the southern hemisphere, +16.05°; and of the northern, 15.30°; and for the whole earth, 15.67°, a result agreeing closely with Forbes and Von Waltershausen.
(4) In a similar manner new charts of isobars, based on the newest data collected by Rikatcheff, Hann, Buchan, etc., have been compiled by Ferrel, which, together with charts of the annual inequality, are all upon a polar projection.
(5) The general circulation of the atmosphere is deduced by reasoning based on the charts and the mechanical principles previously deduced.
PRESSURE AND ISOBARS. The normal distribution of atmospheric pressure in Europe has been further elucidated in an important memoir by Buys-Ballot, published in the Nederlands Jaarbooek.
Buchan's paper on the diurnal barometric periods, in which he showed the decided influence of the relative distribution of land and water, has not yet been followed by the promised second part. And the conclusion formerly deduced by the present writer still seems to be inevitablemi. e., that the diurnal and annual variations in the distribution of heat and moisture induce corresponding changes in the wind currents and consequently in the barometric pressure, the exact laws of which are contained in the formulæ of Ferrel's “Motions of the Winds on the Earth's Surface," though not developed by him with special reference to this interesting point.
This subject has been recently studied by Chambers, Broun, Belfour, Stewart, and Blanford. Starting with the idea of Kreil and Espy and others, that the expansion of the lower strata up to 10 A.M. is resisted by the weight of the surrounding atmosphere, thereby producing an increase in the pressure at the earth's surface, Blanford seeks to show that, at least in India, the greater part of the barometric irregularities result from the transfer of air from land to sea and back again. In this explanation, however, Blanford makes no use of the important laws of dynamics, according to which the distribution of density (as depending on temperature and moisture and latitude) definitely fixes the law according to which the pressure must vary with the location and the time.
Professor Balfour Stewart, in some remarks on Mr. J. A. Broun's discoveries, maintains that the electrical state of the atmosphere may very plausibly be introduced to explain the general disturbances or tides in the barometric pressure.
Mr. Buchan has received from the Royal Society of Edinburgh the Macdougall-Brisbane gold medal for his paper on the diurnal oscillations of the barometer.
PRECIPITATION, CLOUDS, ETC. The question as to the existence of fog vesicles is reviewed by Von Obermayer, who concludes that the assumption of fine drops of water suffices to explain all phenomena that have hitherto been ascribed to vesicles, and that the formation of fine drops is much more plausible on account of its simplicity. Angus Smith has observed in Iceland fog particles of 300 inch diameter, or ten times that of the vesicles observed by Saussure.
Malloch has attempted to determine the altitude of the clouds by the comparison of photographic pictures taken simultaneously at two stations. This method, which was earnestly advocated by the author in 1871, seems calculated to give better results than any other, although demanding special precautions. Malloch estimates his extreme errors at three per cent. of the whole. He found the cirri of July and Angust to be at an altitude of from 22,000 to 27,000 feet; large cumuli (the bases) at 6000 or 7000 feet; rainclouds appeared at all altitudes up to 4000 feet.
K. Antolik, of Hungary, calls attention to the remarkable phenomena shown when frictional electricity is allowed to act upon a quiescent cloud of tobacco smoke, which has flowed down upon and spread over a horizontal table. In this cloud he is able to reproduce the appearance of the most delicate cirro-cumuli, the cumuli, the mares’-tails, and other modifications of the forms of clouds. He would by these phenomena endeavor to explain the mode of forma