I can be a flash. Her ponies were restive; they Jesus, Lover of my soul- lieve it, when I think of Eily. What แ Can you "Ah! a message to Eily. Yes, tell her that I did as she wished. I conquered, after all. I didn't go. She'll know what I mean. Tell her I didn't go. Tell her that I tore up the note, and sent it back in an envelope, without a word, to the hotel. And then I thought, if I stayed in England, the same would come over again. And I remembered my father's land. I thought - if I went and worked hard Russell.' Jesus-Jesus-Lover of my soul, I hadn't tried it then. But I'll try it The large eyes opened with the liquid smile of their boyhood. Russell was gone. "What do you mean?" asked Eily, all unconscious. "I'll tell you some time. Russell knows. Ah, darling darling!" His eyes, as she gazed down into them, were full of adoration. His countenance, once so cold, seemed trausfigured. Eily, look! do you recognize our star? Do you remember my telling you that you would never draw Russell up there?" He stopped suddenly; he thought of his dream, of Eily's face in those radiant heights. An old prophecy sounded in his ears. Was it Russell's voice, answering far away? "THEY THAT BE WISE SHALL SHINE AS THE BRIGHTNESS OF THE FIRMAMENT, AND THEY THAT TURN MANY TO RIGHTEOUSNESS AS THE STARS FOREVER AND EVER." E. CHILTON. From The Nineteenth Century. I. stands upright in higher latitudes such was the simplest expression of Dove's theory given in text-books.1 2 DURING the last thirty years the data Under this provisory hypothesis meof meteorology have been accumulated | teorology made an immense progress, with a very great rapidity, and the chief and some five-and-thirty years ago, desideratum of the moment is, to con- Leverrier in France, and Fitzroy in this struct with these data such a general country, ventured for the first time to theory of the circulation of the atmo- foretell weather twenty-four hours in sphere as would embody the distribution advance, or at least to send out warnof heat, pressure, moisture, and winds ings as to the coming storms. This over the surface of the earth, and rep-bold step brought meteorologists face to resent them as consequences of well- face with a quite new problem. From established mechanical laws. The old the air-pressure, the temperature, the provisory hypothesis of atmospheric moisture, and the winds observed at a circulation, advocated by Hadley in certain hour of the day at various spots 1735, and further elaborated by Dove and telegraphed to a central station in our century, can be held no more, they had to infer the next probable and a new theory has become of abso- state of weather. So, leaving aside the lute necessity. great problems of atmospheric circulaWe all have learnt Dove's theory at tion, they directed their attention to the school, even though we often found it changes of weather rather than to the difficult to understand. The air, greatly causes of the changes. For this purheated on or near the equator, rises in pose purely empirical laws were of great the same way as it rises in the summer value. When the meteorologist saw on over a sunburnt plain. On reaching the a weather-chart a region of low atmohigher strata of the atmosphere it flows spheric pressure, with winds blowing towards the poles, but, owing to the in spirals round and towards its centre, speed of rotation which it has acquired he named it, by analogy with real in the lower latitudes, it is deflected - cyclones, a cyclonic disturbance " to consider the northern hemisphere or (6 a cyclone," giving the name of only to the right, and blows in the " anti-cyclone" to the region of high upper strata as a current from the atmospheric pressure—and he studied south-west. To compensate this flow, the tracks of both disturbances in their air rushes on the earth's surface advance across the oceans and the contowards the equator, and as it also is tinents. He did not inquire for the deflected from its course by the same moment into the causes of the disturbinertia of rotation, it appears in the ances; he took them as facts, and, tropics as a trade-wind blowing from following Buys Ballot's law, he said the north-east. However, the upper that the wind will blow as a rule from warm current does not flow all the way the region of high barometric pressure to the pole in the upper regions; it is (the anti-cyclone) to the region of low gradually cooled down, and in about the pressure (the cyclone), with a certain thirtieth degree of latitude it begins to deflection to the right or to the left. descend to the earth's surface, where it Immense researches were made to study meets with the cold polar current. A the routes followed by the centres of struggle between the two winds ensues, barometrical minima, and we now have and it lasts until they make a temporary splendid atlases showing the normal peace by blowing side by side, or one tracks of cyclones across the Atlantic above the other; the struggle giving Ocean, over Europe and the States, in origin to storms and to changes of wind which are fully analyzed in Dove's theory. A rope without end rolling over Leipzig, 1860, p. 568. two pulleys, one of which lies horizontally near the equator and the other 4255 1 E. E. Schmid, Lehrbuch der Meteorologie, 2 See W. Bezold's short sketch of meteorological progress in Sitzungsberichte der Berlin Akademie der Wissenschaften, 1890, ii. 1295, sq. Japan, in the Indian Ocean, and so on, more and more evident, especially since at various seasons of the year. With the movements of clouds began to be these empirical data meteorologists systematically studied and observatories attained such a perfection in their were erected on high mountains; and weather forecasts that in five cases out of six their previsions are now correct, while the coming gales are even foretold with a still greater accuracy. However, the very progress achieved demonstrated the necessity of a more thorough knowledge of the too much neglected upper currents of the atmosphere. In Dove's scheme, the upper equatorial current, after part of it had been sent back to the equator, was entirely abandoned to itself, to make its way as best it could against the opposed polar winds; but the existence of a strong, nearly permanent, and relatively warm upper wind blowing towards the east in our latitudes — which was only probable thirty years ago - became 2 1 Besides the earlier works of Ley (Laws of the Winds Prevailing in Western Europe, Part I. 1872) and Köppen (Wissenschaftliche Ergebnisse aus 78), we have now the splendid work of W. J. Van Bebber, which embodies the tracks of all cyclones in Europe for the last fifteen years (Die Zugstrassen der monatlichen Uebersichten des Wetters, 1873 works for Russia. 2 Observations in Siberia, namely, at the graphite works on Mount Alibert, at a height of eight thou this wind remained unexplained in Dove's theory, while in Maury's scheme of atmospheric circulation, which is still in great vogue in our schools, there was even substituted for it a current in an opposite direction, which does not exist, and which Maury himself could not account for. An entire revision of the subject was thus necessary, and this revision has been done by the American meteorologist Ferrel, in a series of elaborate works which are only now beginning to receive from meteorologists the attention they fully deserve. Ferrel's theory is based upon considerations as to the laws of motion of liquids and gases of different densities. If the whole atmosphere were equally heated in all its parts, and at full rest, the air would be disposed in horizontal layers, of greater density at the bottom, and of decreasing density towards the top. Considering some part only of der barometrischen Minima, für 1875-90), the rethe atmosphere, from pole to equator, searches of Blanford, S. E. Hill, and Elliot in the “Indian Meteorological Memoirs" and "Cyclone and neglecting the curved surface of Memoirs," Part IV. (published by the Meteoro- the earth, we should thus have somelogical Department of India), the work of E. Knipping for Japan, in “ Annual Meteorological Report thing analogous to a trough filled with for 1890," Part II. Appendix, and several excellent layers of different liquids. If one end of the trough were now warmed, and the other end were cooled, the layers would be horizontal no more. They would be inclined, but in two different ways; the lower ones would be inclined towards the warm part, while in the upper layers the inclination would be the reverse. A full circuit of the lighter liquids flowing one way on the surface, and of heavier liquids flowing the other way on the bottom, would thus be established. The same would happen in our atmosphere with the lighter, warm currents and the heavier, cold currents if the earth had no rotation on its axis. But it rotates- the solid globe as well as its gaseous envelope—and this modifies the whole circulation. The air which flows from the sand feet (520 N. lat.), were especially conclusive. Alibert's observations, buried in the Russian Trudy of the Siberian expedition, proved the exist ence of a nearly permanent W. and W. N. W. wind on the top of the peak, and they showed at the same time that the average yearly temperature on the top of the peak was by some fourteen to eighteen Fahrenheit degrees higher than it otherwise ought to be. When I visited the then abandoned mine in 1864, and saw the peak dominating all surrounding mountains, and could judge of the force of the west wind from the immense works accom plished to protect the road which was traced on the western side of the peak, I could not refrain from explaining the extraordinarily great height of the snow-line in east Siberia by the existence of a relatively warm equatorial current blowing with a great force at a height of from eight thousand to ten thousand feet in a latitude of 52° N. Later on the observations which I brought from the Voznesensk mine (COo N., altitude 2,620 feet) induced my friend Ferd. Müller, who calculated those observations, to conclude that in higher latitudes the same current descends still lower to the earth's surface, and still maintains some of its initial warmth, 3 See James Thomson's paper "On the Grand Currents of the Atmosphere," in Philosophical Transactions, A. 1892, p. 671. and mathematical analysis. By the end of his life (he died in 1891) he embodied his theory in a well-written and suggestive popular work, which fully deserves being widely known. All taken, his views so well agree with the facts relative to the movements of the atmosphere, and they give such a sound method for further investigation, that they are sure to become for some years to come the leading theory of meteorology. They already have given a strong impulse to theoretical research, and have created a whole literature in Austria and Germany.4 equator to the poles maintains, not its | parts to the test of both observation Such are, very briefly stated, the leading features of the theory which Ferrel laboriously worked out during the last thirty years, submitting all its 1 Full tables giving the eastward (or westward) velocities for each latitude, under the two different hypotheses, have been calculated for the Meteorologische Zeitung, 1890, pp. 399 and 420. 2 Ferrol seems not to have been aware that the same had been demonstrated, by R. Lenz, for rivers (about the year 1870) in a discussion of Baer's law, applied to the Amu River, in the "Mémoires" of the St. Petersburg Academy. See 3 Wm. Ferrel, "A Popular Treatise on Winds, Another theory of the general circulation of the atmosphere which is also awakening a good deal of interest among physical geographers was propounded in 1886 by Werner Siemens, and further developed by him in 1890.5 4 Roth has already abandoned the mathematical objections he had raised against Ferrel's theory in the Wochenschrift für Astronomie, 1888. The objections raised by Teisserenc du Bort and Supan against the " density surfaces" have been answered by Professor Davis in Science, and are not shared by the most prominent meteorologists. And the mathematical analysis of Professor Waldo, Sprung (the author of the well-known "Treatise of Meteorology"), M. Möller, and Pernter has further confirmed the accuracy of the theory. So also Hildebrandsson's observations of upper clouds (Annuaire de la Société météorologique de France, xxxix. 338), Teisserenc du Bort's high-level isobars, and Guaran de Trommelin's researches relative to coast-winds. The transport of the Krakatoa dust and Abercromby's observations of clouds having rendered the existence of an upper east current very probable on the equator, Pernter has mathematically deduced from Ferrel's theory the exist ence of such a current in a belt 4° 45′ wide on both sides of the equator, and he therefore has withdrawn the restrictions he had previously made in a lecture (published in Nature, 1892, xlv. 593) in favor of Siemens' views. It must be added that the idea of three superposed currents blowing in spirals may have been suggested to Ferrel by a communication of James Thomson to the British Association in 1857. Such was, at least, the claim raised and developed at some length by the Glasgow professor before the Royal Society in a Bakerian lecture, now published in the "Transactions" (A. 1892, pp. 653-685). Though Thomson's paper was never published, and only given in a very short abstract without a diagram (the diagram in the "Transactions" is now published for the first time), the few lines in which his theory was stated (British Association Reports, Dublin, 1857, pp. 38, 39) contained the idea clearly expressed. It is certainly a matter of great regret that James Thomson has not returned to this subject. 5"Ueber die Erhaltung der Kraft im Luftmeere, ,"in "Sitzungsberichte der Berlin Akademie The case), must originate in the lower current, immense aerial waves rolling at a great speed. We do not generally see them, but when the lower current is so much saturated with moisture that clouds are formed in it, we do see a system of wave-like parallel clouds, which often extend over wide parts of the sky. To calculate the sizes of the waves in different cases is extremely difficult, if not impossible; but by taking some simpler cases Helmholtz and Oberbeck showed that when the waves on the sea attain lengths of from sixteen to thirty-three feet, the air waves must attain lengths of from ten to twenty miles, and a proportional depth. Such waves would make the wind blow on the earth's surface in rhythmical gushes, which we all know, and they also would more thoroughly mix together the su perposed strata, dissipating the energy stored in strong currents. These views are so correct that they undoubtedly will throw some new light, as they already begin to do, upon the theory of cyclones.1 Siemens did not consider that air might | must arise in this case, in the same way flow down the density surfaces, as sup- as they are formed on the sea. posed by Ferrel and Helmholtz, and upper current, if it is inclined towards admitted by many meteorologists, and the earth's surface (as is often the he maintained that the source of the energy required for all disturbances of equilibrium in the atmosphere must be looked for in the unequal heating of its different strata by the sun, and in the unequal loss of heat through radiation in space. From these considerations he inferred the existence of an ascending current in the equatorial belt, an upper warm current, and a cold polar current. As to the eastward and westward directions of these currents, he made the very just remark that the energy of rotation of the whole atmosphere must remain constant and unchanged, even though masses of air move from one latitude to another. The velocity of rotation of the atmosphere in tropical latitudes must therefore lag behind the rotation of the earth, and it must outstrip it in higher latitudes, mathematical calculation proving that the thirty-fifth parallel is, in both hemispheres, the line of division between the two. The general system of air circulation deduced from these principles is very similar in its results to the system of Ferrel; but the interest At the same time, Bezold is now enand importance of Siemens' views lie deavoring to reconstruct meteorology elsewhere. His memoirs were an ap- from the point of view of thermodypeal and an attempt to apply the princi-namics; 2 and the well-known Austrian ples of thermodynamics to the aerial meteorologist J. Hann, whose work is currents, and they have opened the exciting just now a great deal of interway for a series of important researches, which, however, are not yet sufficiently advanced to be discussed in these pages. And, finally, a third new point of view has been introduced into the same discussions by Helmholtz. Sitting one day by the seaside, and observing how wind blows on the surface of the sea by sudden gushes, how it originates waves, and how they grow when wind blows with an increasing force, Helmholtz came to consider what would happen with two air currents blowing one above the other in different directions. A system of air waves, he concluded, der Wissenschaften," March, 1886, p. 261;"Ueber das allgemeine Windsystem der Erde," in same publication, 1890, ii., p. 629. est, has openly broken with the old theory as regards the origin of cyclones and anti-cyclones. From observations made for several years in succession on the top of the Sonnblick — a peak twelve Wetter," and "Die Energie der Wogen und des 1 H. Helmholtz, "Zur Theorie von Wind und Windes," in the "Sitzungsberichte" of the Berlin Academy, 1889, ii. and 1890, ii. Oberbeck's calcu lations of the waves are given in the Meteorolo gische Zeitung, 1890, p. 81. 2 "Zur Thermodynamik der Atmosphäre," in "Sitzungsberichte" of the Berlin Academy of Sciences, 1888, p. 485; same year, p. 1189; 1890, p. 355; and 1892, p. 279. 3 "Das Luftdruckmaximum vom November, 1889," in "Denkschrift der Wiener Akademie der Wissenschaften, 1890, Bd. lvii., p. 401. "Bemerkungen über die Temperatur der Cyclonen und Anticyclonen," in "Meteorologische Zeitschrift," 1890, p. 328. |