It passes into the atmosphere, and, moving with it, comes like carbonic-acid gas into the neighborhood of plants deprived of locomotion, to whose nutrition it contributes. There it is fixed in its travels, falls to the ground in decayed vegetable matters, forms arable land, and renders the soil fertile. The ocean, therefore, is to be considered as the main reservoir of nitrogenous compounds, and is, through the currents of the atmosphere, the regulator of the annual distribution of nitrogen over the continents.-6 B, LXXX., 175.

FAYE'S THEORY OF STORMS.

In his debate with M. Peslin, Faye has stated some of the features of his views in regard to atmospheric storms as follows: First, cyclones, hurricanes, typhoons, tornadoes, and waterspouts are phenomena of one and the same mechanical nature, and to all of which the same general explanatory theory will apply. Second, since the eye can embrace the two latter phenomena in their totality, while the other three classes of storms are spread over too vast an extent of territory for any one observer to seize all their features directly, therefore we ought at first to begin our discussion and investigation with the consideration of tornadoes and waterspouts, at least if we desire to base our conclusions upon facts only. Third, the greater part of meteorologists attribute these phenomena to a vertical aspiration, whose existence they gratuitously assume at the commencement of their investigation. Under certain statical conditions of the atmosphere this aspiration can, according to them, develop mechanical effects of astonishing power. According to them the gyration which is so characteristic of these storms is only an incidental matter, resulting simply from the reaction of the ground upon the horizontal currents, that ground being animated by its slow daily rotation. This reaction, which changes by only 40° the direction of the lower trade-winds in their long course, is made to describe many circumferences in the space of a few yards and in the interval of a few seconds, in the course of these pretended horizontal currents, whose existence not a single observer has as yet noticed. According to the theorists, these latter converge violently from all sides toward the lower orifice of the waterspout or the tornado, in order then to spring vertically through this

narrow orifice up to the region of the clouds under the form of a column, surrounded by vapors condensed by cooling, and spreading as they ascend. Fourth, on the contrary, I submit that the common origin of all these phenomena is found in the upper currents, whose power and directions are clearly shown to our eyes by the clouds, and not in the lower strata, where an almost perfect calm continually reigns. Not, of course, that a calm reigns at the precise spot where the waterspout exists at any moment, but all about it. Upon this capital point, so easy to demonstrate, so frequently denied by observers, and which lends so much to the solution, all the witnesses are agreed. This does not prevent the aspiration theorists from placing violent currents, like immovable layers, around the heart of this perfect calm, which the waterspout or the tornado does not disturb for an instant in its rapid course. Never have we seen in science a similar disregard of facts; a strange indifference which is explained only by the influence of a very ancient and very extended prejudice, whose history I have traced in the Annuaire for 1875, and which has caused meteorologists to replace facts by theories upon the stability or instability of atmospheric equilibrium.-6 B, LXXX., 660.

THE EFFECT OF MOVEMENT OF THE AIR ON THE BAROMETER.

M. Faye having stated in his defense of the law of storms that the barometer does not measure the weight of the atmosphere above us, but that its indications are to be interpreted by dynamical and not statical principles, this idea has been made by Montigny the subject of a communication to the Belgian Academy, on the different pressures exerted by the air upon the barometer, according as it is in movement or quiet, and upon the estimation by means of the barometer of altitudes in balloon ascensions. Montigny has communicated some five or six memoirs on the relation between the height of the barometer and the pressure of the wind. Among them is a series of interesting determinations of the height of a point in the cathedral of Anvers, by means of barometric observations taken under very varied influences as regards the direction and velocity of the wind. These observations had especially as their object to show that the law of diminution of pressure is not the same when

the air is in movement as when it is at rest. Barometric measures made in the tower of the cathedral at Anvers when the air was calm gave results sensibly accordant with the true height as measured by the level. On the other hand, measurements made when the west wind prevailed gave results too high, and those made when the east wind prevailed gave results too low, the difference being fourteen feet. It does not appear, however, that Montigny has taken account of the relative directions between the wind and the opening of the windows and doors of the room in which he was placed-a point which, as is well known from recent investigations, is of the highest importance if so great accuracy would be attained. Bull. Acad. de Belgique, Bruxelles, 1875, 820.

ON THE ACCURACY OF THE ANEROID BAROMETER,

The increasing accuracy of the aneroid barometers as manufactured by the best makers, and the numerous applications of this instrument to the determination of altitudes, have led to several excellent investigations into the errors and reliability of the instrument, among which one of the best is due to G. Grassi, recently published in the supplement to the Meteorologia Italiana. The first instrument examined by him was made by Casella, of London, which was compared with an excellent siphon-barometer. Subsequently a number of others, some of them made by different makers, were ob tained, and subjected to the same course of investigation. Grassi summarized his results as follows: First, aneroids that are subject to great variations of pressure need corrections which have a regular progression, and are generally of very similar form. Second, each aneroid must have its own proper corrections. Third, there exist pressures for which the corrections are nearly constant. Fourth, there exist other pressures at which the corrections experience sudden changes, sometimes an increase, sometimes a decrease. Fifth, if the corrections are plotted as curves, the ascending or descending portions of these will be sensibly parallel. Sixth, sudden jumps are in a positive direction if the preceding period is one of increasing correction, and vice versa; the jumps are negative if the preceding period is one of diminishing correction. Seventh, the magnitude of a sudden jump is pro

portional to the extent of the period that precedes it.--Supplemento alla Meteorologia Italia, Rome, 1875, 28.

THE SIMULTANEOUS EXISTENCE OF DIFFERENT CURRENTS OF AIR.

The exact knowledge of the presence of several currents of air in the atmosphere around us is of so great importance to meteorology that we record here the observations made by Chapelas in France. On the 30th of April, at noon, he observed a clear sky with a feeble northeast wind. At two o'clock P.M. a slight thread of cirrus was seen moving rapidly from the west-southwest or southwest, the surface wind remaining still northeast. On the first of May both wind and clouds moved from the southwest at ten o'clock A.M.; and at one thirty P.M. a strong storm, followed at night by clouds and wind from the northwest. On the second of May at seven P.M. there appeared a balloon driven by a wind from the west-northwest to the northeast, while at the surface of the earth it was quite calm. The balloon descending in the Luxembourg quickly, when it arrived at an altitude of about one hundred and fifty feet met a current diametrically opposed to that which it had experienced above, and was carried by it toward the southeast.-6 B, LXXX., 1176.

ON THE LAWS OF CYCLONES.

The distinguished astronomer, Faye, of Paris, having been led from his study of solar spots to investigate the subject of terrestrial storms, has developed numerous novel views, which will be found fully noticed elsewhere, and has lately applied these views to the study of the hurricane of February 25, 1860, in the Indian Ocean. In this hurricane some forty vessels were destroyed, and their loss is attributed by him in great part to implicit confidence of the navigators in the laws for avoiding the centres of hurricanes that have hitherto been promulgated. It is well known that Mr. Meldrum, by studying this same storm, was led to certain modifications of the ordinary hurricane laws, but Faye differs widely from his conclusions. Similarly Captain Ansart proposed to reject the circular theory of cyclones, and to substitute ellipses for the spirals of Mr. Meldrum. By referring to the original observations, so far as they are available for

the study of this storm, Faye concludes that it is necessary to take account of the trade-winds in enunciating the laws of those storms which occur in the regions of those winds; and he proposes the following practical conclusions which he would submit to navigators:

"In order to determine the position of the centre of a cyclone in the region of the trade-winds, if the observer finds himself within its borders in the semicircle exposed to the winds, he ought to apply the ordinary rules, not to the wind that he experiences, but to that wind which, conjoined with the known trade-wind of that region, would give as its resultant the wind actually observed by him, both in direction and force. If we obtain graphically two distinct determinations of the centre, we can, if there is occasion to do so, correct this first approximation by introducing therein the velocity of translation of the centre of the cyclone or of the vessel."-6 B, LXXXI., 64.

DISTRIBUTION OF ATMOSPHERIC PRESSURE.

One of the most important meteorological publications of the year consists in that by Rikatcheff on the distribution of atmospheric pressure in European Russia. Having access to all the original documents, and having himself visited many Russian stations in order to secure perfect accuracy of instruments, Rikatcheff has been in a favorable position to give us the very valuable memoir which he has succeeded in compiling. The results of his work are given in the shape of a series of tables and charts, showing the distribution of pressure throughout Russia and the neighboring countries. In concluding his work, he says that there are still wanting the necessary data in order to use some half-dozen stations for which observations are at hand. But, apart from these, the charts of isobars which he gives represent very approxi mately the distribution of pressure for each month and for the whole year. According to these, by simple interpolation, the mean height of the barometer for any given point of Eastern Russia can be obtained with an accuracy of about one millimeter; and for Western Russia with an accuracy of one fifth of a millimeter. There is no successful attempt at an explanation of the low barometer in Northern Europe, and the author appears to be quite in ignorance of the theoretical