obtained by measurements of other properties of salt solutions, the electric conductivity, the depression of the freezing point, &c., and the theory is compared with practice by seeing if the values of "," as determined, say, from freezing point observations, agree with those deduced from the osmotic pressure. The comparison shows that in some cases, some half-a-dozen in all, the two sets of values correspond; in others, and in by far the majority, no such correspondences exist. In these latter instances it is argued, and with a certain amount of experimental evidence, that the salts were not without action on the membrane employed, and that, therefore, diosmose really took place, the membrane was not truly semipermeable. In this way the discordant observations have been put out of court. It is thus apparent that the leading hypotheses of the new theory do not receive confirmation of the weightiest kind from observations on osmotic pressure. Indeed, were they supported by such measurements alone, they would hardly be entertained. Their mainstay, however, ies in the mass of experimental work on many other properties - evidence which it is much easier to obtain than the difficult measurements on osmotic pressurewhich has been correlated and explained by their use. been put forward in favour of the gaseous analogy. Several physicists, starting from entirely different points of view, have arrived at the result that in a dilute solution the dissolved substance should obey laws similar to those which hold for gases. At present the attitude of the prominent upholders of the new theory is one of indifference as to the exact mechanism of osmotic pressure. The numerical agreement between the measurements on solutions and those on gases is regarded as ample justification for considering dissolved substances to be in a pseudo-gaseous condition. Whatever the ultimate explanation of the facts may be, there can be no doubt that the existing speculations on the nature of osmotic pressure and allied phenomena have infused new life into the study of solutions. Indeed, as instigators to fresh inquiry these hypotheses must take rank as the most fruitful of recent times. J. W. RODGER. A SANITARIAN'S TRAVELS. MR. ROBERT BOYLE has travelled round the world no fewer than four times for the purpose of studying sanitary science and preparing the way for the intro It is only fair to add that both hypotheses, from physial as well as chemical standpoints, have met with a easure of adverse criticism. The role played by the embrane has also been questioned. It has been sugested that it is not really semi-permeable, allowing solent only to pass, but just as a porous plug behaves wards a mixture of gases, it allows molecules with difrent momenta to traverse it at different rates. Or, ain, its action has been likened to that of a pallaum film towards hydrogen, compounds being formed th the membrane substance on one side, these becomg diffused and dissociated on the other. If either of ese views be correct the pressures exerted by dissolved Ostances have probably never been measured. On the other hand, important theoretical support has duction of the ventilating and sanitary appliances he has invented. An interesting account of his fourth journey is given in a little book entitled "A Sanitary Crusa ie through the East and Australasia," consisting of a series of papers reprinted from the Building News. In the course of this "crusade" Mr. Boyle visited Burmah, the Malay native states, Sumatra, Siam, Borneo, Java, Australia, New Zealand, Samoa, the Sandwich Islands, and America. Of all the facts noted by him as a sanitarian the most remarkable are those relating to leprosy, a disease which he believes to be spreading to an alarming extent all over the world. He was particularly struck by the gigantic proportions the evil has assumed in Burmah. The steps of the great Shwedagon pagoda at Rangoon, the Mecca of the Indo-Chinese Buddhists, he found to be "closely lined from top to bottom with lepers, suffering from that loathsome disease in its worst forms and most advanced stages." A number of the victims examined by Mr. Boyle "presented a most sickening and awful spectacle." Yet no provision worthy of the name appears to be made for the maintenance or treatment of these poor lepers, who are thus compelled to resort to begging to keep themselves in existence. At Mandalay Mr. Boyle came in contact with horrors of a similar nature. During times of high festival the entrances of the great Arakan pagoda in that city are crowded by hundreds of lepers, so that the visitor has to pick his way carefully among them. In the Sandwich Islands also Mr. Boyle was strongly impressed by the terrible effects of the curse of leprosy, which, he says, has nearly decimated the native population. He has a curious theory to the effect that the propagation of leprosy has been to a large extent connected with cannibalism, the disease "being spread wholesale through the eating of infected bodies." He has frequently seen in New Caledonia and the South Sea Islands human bodies "hanging up in the natives' huts, intended for future repasts, though then in an advanced stage of decomposition and exhaling a sickening odour." The little book is by no means occupied only with these terrible subjects. Reference is made to many interesting things which came under Mr. Boyle's observation in the course of his journey. We may especially note the impression produced upon him by Buddhist temples and various classes of objects associated with Buddhism in Burmah. Pagan, an ancient capital of Burmah, situated on the Irrawaddy between Mandalay and Rangoon, contains an enormous number of Buddhist temples of various sizes and styles of architecture, and the city, as seen from the river, is described by Mr. Boyle as one of the grandest and most impressive sights he has ever seen." Lower down the Irrawaddy below Prome there is a cliff about two miles long and 300 feet high, on the face of which are carved innumerable figures of Buddha ranged in tiers from the bottom to the top. He thinks that some of these figures cannot be less than twenty feet high. Many of them are richly gilded, and the whole forms "a very brilliant and curious sight." We reproduce an illustration showing the great recumbent figure of Buddha, in the province of Pegu, of which Mr. Boyle reports that "it is said to measure about 270 feet in length by 70 feet at the shoulder." In a paper read lately before the Anthropological Institute (see NATURE, November 10, p. 46) Major R. C. Temple gives the length as 181 feet and the height at the shoulder 46 feet. This remarkable monument is built of brick, and Major Temple speaks of it as "well proportioned throughout." It is supposed to have been produced in the fifteenth century. It was hidden from view by jungle until 1881, when it was accidentally discovered by a railway contractor. GAUSS AND WEBER. as IN N bringing before our readers the contents of a circular we have received with respect to the erection of a monument, in Göttingen, to the two world-renowned scientific workers and friends, Charles Frederick Gauss and William Weber, we do so, knowing that every scientific man, whether he be astronomer, mathematician, or physicist, will be only too glad to have a chance of paying some tribute, however slight, to their memory. Only about a year has gone by since the younger of the two, William Weber, passed away, having brought glory to the University of Göttingen, which was radiated throughout the whole scientific world. The work which both have done in the service of science cannot be said to be the property of their followers alone, but is a precious heirloom of mankind, which has proved, and will continue to prove in the future, valuable in mar ways in the service of technics, in methods of commer cation, and in civilization generally. Gauss, who is almost unequalled among the scholars of the century, has not only left imposing landmarks a his great mind in all domains of pure mathematics, but be has also by his work furthered all departments of its appl cations in astronomy and physics, while his investigations have become standard for the theoretical as well as for the observational side. What Gauss did for magnetism, Weber, whom Gauss had chosen for his fellow-worker, attracted by his useful work on acoustics, did for the strength of galvani currents, for their impelling electromotive forces, and f their resistances. Further, in teaching how to measure these quantities in absolute units, he has furnished extremely importa methods for their investigation. In this way not or has the science itself been furthered, but a firm basis f the development of electro-technics has been formed, the soundness of which is proved by its general adoption and which has contributed greatly to the tremendous advare witnessed during the last ten years. The pamphlet the goes on to say: "It is not the purpose of these linest enlarge on the eminent works which we owe to the co-operation of these great investigators; we can on call to mind the fertile researches on the laws of t earth's magnetism, from which as it were a new branch of physics has developed; further, the attempts encompass the phenomena of electrostatics, electro dynamics, and induction by one single law, attemp which, however a future generation may judge of ther will mark an important epoch in scientific develop ment; and further, we may recall the most popular rest of their co-operation, viz. the erection of the fir telegraph practically adopted for communication at a distance." Since the year 1877 the birthplace of Gauss Es possessed a memorial of him, but Göttingen, the plat where he and Weber worked, and where the former died and which consequently became celebrated, possesses such memorial. That this should be remedied is the object of this circular, and one has only to glance des the list of names attached to it-about 275 altogetherto see that it includes most of the learned men in Gemany, and those of many distinguished foreigne Among these we are glad to see the name of Lor Kelvin, President of the Royal Society. The acting committee is composed of Prof. Klein. L v. Meier (Curator of the University), F. Merkel (Fr rector of the University), G. Merkel (Over-burgomaste Profs. E. Riecke, E. Schering, W. Schur, W. Voigt Weber, and S. Benfey (banker), and it is to the mentioned that subscriptions should be addressed Benfey, Bankgeschäft, Göttingen). The list will rema open until April 1, 1893. toric Archæology; the Rumford Medal to Mr. Nils C. Dunér (received by the Swedish Minister), for his Spectroscopic Researches on Stars; a Royal Medal to Mr. J. N. Langley, F.R.S., for his work on Secreting Glands, and on the Nervous System; a Royal Medal to the Reverend Prof. Pritchard, F.R.S., for his work on Photometry and Stellar Parallax; the Davy Medal to Prof. François Marie Raoult, of Grenoble, for his researches on the Freezing Points of Solutions, and on the Vapour Pressures of Solutions; and the Darwin Medal to Sir J. D. Hooker, F R.S., on account of his important contributions to the progress of Systematic Bny, as evidenced by the "Genera Plantarum" and the" Flor. Indica," but more especially on account of his intimate association with Mr. Darwin in the studies preliminary to the "Origin of Species." The Society next proceeded to elect the Officers and Council for the ensuing year. The following is a list of those elected:-President: The Lord Kelvin. Treasurer: Sir John Evans. Secretaries Prof. Michael Foster, The Lord Rayleigh. Foreign Secretary: Sir Archibald Geikie. Other Members of the Council: Capt. William de Wiveleslie Abney, Sir Benjamin Baker, Prof. Isaac Bayley Balfour, William Thomas Blanford, Prof. George Carey Foster, Richard Tetley Glazebrook, Frederick Ducane Godman, John Hopkinson, Prof. Joseph Norman Lockyer, Prof. John Gray McKendrick, William Davidson Niven, William Henry Perkin, Rev. Prof. B. Price, The Marquis of Salisbury, Adam Sedgwick, Prof. William Augustus Tilden. In the evening the Fellows and their friends dined together at the Whitehall Rooms, Hôtel Métropole. The following is the address delivered at the anniversary meeting by Lord Kelvin : Since our last Anniversary Meeting, the Royal Society has lost 27 Fellows on the Home list, and 5 Foreign Members, a sadly great number. Pedro (Dom) II. (d'Alcantara), Emperor of Brazil, December 5, 1891. Ramsay, Sir Andrew Crombie, December 9, 1891, aged 77. Stas, Jean Servais, December 13, 1891, aged 78. Bennett, Sir James Risdon, December 14, 1891, aged 82. Devonshire, William Cavendish, 7th Duke of, December 21, 1891, aged 83. Russell, William Henry Leighton, December 28, 1891, aged 68. Kronecker, Leopold, December 29, 1891. Wood, John, December 29, 1891, aged 66. Airy, Sir George Biddell, January 2, 1892, aged 90. 1892, aged 81. Adams, John Couch, January 21, 1892, aged 72. Grant (Lieut. -Col.), James Augustus, February 11, 1892, aged 65. Hunt, Thomas Sterry, February 12, 1892, aged 66. Knowles, Sir Francis Charles, March 19, 1892, aged 90. Bramwell, George William Wilsher, Lord, May 9, 1892, aged 84. Aitken, Sir William, June 25, 1892, aged 67. chorlemmer, Carl, June 27, 1892, aged 58. Clark, Frederick Le Gros, July 19, 1892, aged 82. Calver (Captain), Edward Killick, October 28, 1892. During the past year, in the mathematical and physical section. of the Philosophical Transactions," eighteen papers have been published, and in the biological section, eleven; the two sections together containing a total of 1235 pages of letterpress and 50 plates. Of the "Proceedings," fourteen numbers have been issued, containing 1223 pages and 20 plates. This unusually large bulk is partly accounted for by the publication in the "Proceedings of certain extra matters which the Council deemed likely to interest the Fellows. One part (No. 307), which forms an appendix to volume 1., contains results of the Revision of the Statutes, to which I alluded in my Anniversary Address last year. It consists of a summary of the second and third chapters, and a copy of the Statutes as now revised, followed by an interesting note on the history of the Statutes, which has been drawn up by our senior secretary, Prof. Michael Foster. In addition to these matters, the same number contains a complete list of the portraits and busts at present in the apartments of the Society, compiled by order of the Library Committee, a work which was much needed, as no such list had been made since Weld's Catalogue, printed thirty-two years ago. The new "list" is not a descriptive catalogue, but the names of the painters and donors, and the dates of the gifts, so far as a thorough and somewhat laborious examination of the Council minutes and Journal books has revealed them, are furnished. The list of portraits is followed by a full descriptive catalogue of the medals at present in the possession of the Society, which has been carefully made by our clerk, Mr. James, under the supervision of the treasurer. Another extra number of the "Proceedings" (No. 310) is devoted to a First Report of the Water Research Committee on the Present State of our Knowledge concerning the Bacteriology of Water, by Profs. Percy Frankland and Marshall Ward. It contains 96 pages, full of most valuable information regarding the vitality of micro-organisms in drinking water, to which in a large measure the spread of Asiatic cholera, typhoid fever, and other zymotic diseases is now known to be due. In my Presidential Address of last year, I referred to this Water Committee as having been appointed by the Royal Society, in alliance with the London County Council; and this first instalment of its work seems amply to justify its originators in their expectations of results, most valuable for the public health, from the investigation which has been commenced. A third extra number (No. 311) contains the report of the Committee on Colour Vision. This Committee, from the time of its appointment in March, 1890, held over thirty meetings, in course of which it examined more than 500 persons as to their colour vision, and tried various methods and many kinds of apparatus for colour testing. The report of the results of the whole inquiry contains a large mass of most interesting matter, and the Committee's work ends in a set of practical recommen. dations, from which we may hope that much benefit will come, in the prevention of inconvenience and disaster liable to be produced by mistake of colour signals, both at sea and on railways. Mr. Ellis's communication (Roy. Soc. Proc., November, 1892, vol. ii., p. 191) to the Royal Society of last May, and Prof. Grylls Adams' communication (Phil. Trans., vol. clxxxiii. 1891-92, p. 131) of June, 1891, both on the subject of simultaneous magnetic disturbances found by observations at magnetic observatories in different parts of the world; the award of a Royal medal two years ago to Hertz, for his splendid experimental work on electro-magnetic waves and vibrations; and Prof. Schuster's communication (Phil. Trans. vol. clxxx.. 1889, p. 467) to the Royal Society, of June, 1889, on the "Diurnal Variations of Terrestrial Magnetism,” justify me in saying a few words on the present occasion regarding terrestrial magnetic storms, and the hypothesis that they are due to magnetic waves emanating from the sun. 46 Guided by Maxwell's electro-magnetic theory of light," and the undulatory theory of propagation of magnetic force which it includes, we might hope to perfectly overcome a fifty years' out- standing difficulty in the way of believing the sun to be the direct cause of magnetic storms in the earth, though hitherto every effort in this direction has been disappointing. This difficulty is clearly stated by Prof. W. G. Adams, in the following sentences, which I quote from his Report to the British Association of 1881 (p. 469) "On Magnetic Disturbances and Earth Currents" :-"Thus we see that the magnetic changes which take place at various points of the earth's surface at the same instant are so large as to be quite comparable with the earth's total magnetic force; and in order that any cause may be a true and sufficient one, it must be capable of producing these changes rapidly." The primary difficulty, in fact, is to imagine the sun a variable magnet or electro-magnet, powerful enough to produce at the earth's distance changes of magnetic force amounting, in extreme cases, to as much as 1/20 or 1/30, and frequently, in ordinary magnetic storms, to as much as 1/400 of the undisturbed terrestrial magnetic force. The earth's distance from the sun is 228 times the sun's radius, and the cube of this number is about 12,000,000. Hence, if the sun were, as Gilbert found the earth to be, a globular magnet, and if it were of the same average intensity of magnetization as the earth, we see, according to the known law of magnetic force at a distance, that the magnetic force due to the sun at the earth's distance from it, in any direction, would be only a twelve-millionth of the actual force of terrestrial magnetization at any point of the earth's surface in a corresponding position relatively to the magnetic axis. Hence the sun must be a magnet1 of not much short of 12,000 times the average intensity of the terrestrial magnet (a not absolutely inconceivable supposition, as we shall presently see) to produce, by direct action simply as a magnet, any disturbance of terrestrial magnetic force sensible to the instruments of our magnetic observatories. Considering probabilities and possibilities as to the history of the earth from its beginning to the present time, I find it unimaginable but that terrestrial magnetism is due to the greatness and the rotation of the earth. If it is true that terrestrial magnetism is a necessary consequence of the magnitude and the rotation of the earth, other bodies comparable in these qualities with the earth, and comparable also with the earth in respect to material and temperature, such as Venus and Mars, must be magnets comparable in strength with the terrestrial magnet, and they must have poles similar to the earth's north and south poles on the north and south sides of their equators, because their directions of rotation, as seen from the north side of the ecliptic, are the same as that of the earth. It seems probable, also, that the sun, because of its great mass and its rotation in the same direction as the earth's rotation, is a magnet with polarities on the north and south sides of its equator, similar to the terrestrial northern and southern magnetic polarities. As the sun's equatorial surface-velocity is nearly four and a half times the earth's, it seems probable that the average solar magnetic moment exceeds the terrestrial considerably more than according to the proportion of bulk. Absolutely ignorant as we are regarding the effect of cold solid rotating bodies such as the earth, or Mars, or Venus, or of hot fluid rotating bodies such as the sun, in straining the circumambient ether, we cannot say that the sun might not be 1000, or 10,000, or 100,000 times as intense a magnet as the earth. It is, therefore, a perfectly proper object for investigation to find whether there is, or is not, any disturbance of terrestrial magnetism, such as might be produced by a constant magnet in the sun's place with its magnetic axis coincident with the sun's axis of rotation. Neglecting for the present the seven degrees of obliquity of the sun's equator, and supposing the axis to be exactly perpendicular to the ecliptic, we have an exceedingly simple case of magnetic action to be considered: a magnetic force perpendicular to the ecliptic at every part of the earth's orbit and varying inversely as the cube of the earth's distance from the sun. The components of this force parallel and perpendicular to the earth's axis are, respectively, o'92 and 0'4 of the whole; of which the former could only be perceived in virtue of the varying distance of the earth from the sun The moon's apparent diameter being always nearly the same as the sun's, the statements of the last four sentences are applicable to the moon as well as to the sun, and are important in connection with speculation as to the cause of the lunar disturbance of terrestrial magnetism, discovered nearly fifty years ago by Kreil and Sabine. in the course of a year; while the latter would give rise to a daily variation, the same as would be observed if the red ends of terrestrial magnetic needles were attracted towards an ideal star of declination o° and right ascensi 270'. Hence, to discover the disturbances of terrestria magnetism, if any there are, which are due to direct actier of the sun as a magnet, the photographic curves of the three magnetic elements given by each observatory should be analysed for the simple harmonic constituent of annual perio and the simple harmonic constituent of period equal to the sidereal day. We thus have two very simple problems, each o which may be treated with great ease separately by a ma simplified application of the principles on which Schuster treated his much more complex subject, according to Gaz theory as to the external or internal origin of the disturbance and Prof. Horace Lamb's investigation of electric currents duced in the interior of a globe by a varying external mage. The sidereal diurnal constituent which forms the subject of the second of these simplified problems is smaller, but not mech smaller, than the solar diurnal term which, with the solar ser diurnal, the solar ter-diurnal, the solar quarter-diurnal cos stituents form the subjects of Schuster's paper. The conclusi at which he has arrived, that the source of the disturbance s external, is surely an ample reward for the great labour has bestowed on the investigation hitherto; and I ho he may be induced to undertake the comparatively s extension of his work which will be required for t separate treatment of the two problems of the sidera diurnal and the solar annual constituents, and for each the question :-Is the source external or internal? But even though external be the answer found in each cas we must not from this alone assume that the cause is direc action of the sun as a magnet. The largeness of the solar se diurnal, ter diurnal, and quarter-diurnal constituents found b the harmonic analysis, none of which could be explained by the direct action of the sun as a magnet, demonstrate relatively large action of some other external influence, possibly the electri currents in our atmosphere, which Schuster suggested as a pr bable cause. The cause, whatever it may be, for the sen diurnal and higher constituents would also probably have variation in the solar diurnal period on account of the different of temperature of night and day, and a sidereal and ana period on account of the difference of temperature betwee winter and summer. to answe Even if, what does not seem very probable, we are to be le by the analysis to believe that magnetic force of the s directly perceptible here on the earth, we are quite certain 21 this steady force is vastly less in amount than the abruptly v ing force which, from the time of my ancestor in the Presiden Chair, Sir Edward Sabine's discovery,1 forty years ago, of = apparent connection between sunspots and terrestrial magnet storms, we have been almost compelled to attribute to disturb“. action of some kind at the sun's surface. As one of the first evidences of this belief, I may quote * following remarkable sentences from Lord Armstron Presidential Address to the British Association at Newcast in 1863 "The sympathy also which appears to exist between f operating in the sun and magnetic forces belonging to the e merits a continuance of that close attention which it has alr received from the British Association, and of labours s General Sabine has, with so much ability and effect, devo.ell the elucidation of the subject. I may here notice that most markable phenomenon which was seen by independent obsat two different places, on September 1, 1859. A sudden a burst of light, far exceeding the brightness of the sun's surta was seen to take place, and sweep like a drifting cloud ove portion of the solar face. This was attended with ma disturbances of unusual intensity, and with exhibitions of of extraordinary brilliancy. The identical instant at which effusion of light was observed was recorded by an abrup strongly-marked deflection in the self-registering instrume Kew. The phenomenon as seen was probably only part of actually took place, for the magnetic storm in the midst of** it occurred commenced before, and continued after the ev If conjecture be allowable in such a case, we may suppose this remarkable event had some connection with the meat1 Communication to the Royal Society, March 18, 1952 (Pre vol. clxii. p. 143). hich the sun's heat is renovated. It is a reasonable supposition at the sun was at that time in the act of receiving a more than sual accession of new energy; and the theory which assigns the aintenance of its power to cosmical matter, plunging into it ith that prodigious velocity which gravitation would impress on it as it approached to actual contact with the solar orb, ould afford an explanation of this sudden exhibition of intensied light, in harmony with the knowledge we have now attained, at arrested motion is represented by equivalent heat." It has certainly been a very tempting hypothesis, that quanties of meteoric matter suddenly falling into the sun is the cause, one of the causes, of those disturbances to which magnetic orms on the earth are due. We may, indeed, knowing that eteorites do fall into the earth, assume without doubt that uch more of them fall, in the same time, into the sun. Astroomical reasons, however, led me long ago to conclude that eir quantity annually, or per century, or per thousand years, .much too small to supply the energy given out by the sun in eat and light radiated through space, and led me to adopt unualifiedly Helmholtz's theory, that work done by gravitation n the shrinking mass is the true source of the sun's heat, as iven out at present, and has been so for several hundred thouand years, or several million years. It is just possible, howver, that the outburst of brightness described by Lord Armstrong may have been due to an extraordinarily great and udden falling in of meteoric matter, whether direct from extralanetary space, or from orbital circulation round the sun. But t seems to me much more probable that it was due to a refreshed rightness produced over a larger area of the surface than usual y brilliantly incandescent fluid rushing up from below, to take he place of matter falling down from the surface, in consequence f being cooled in the regular régime of solar radiation. It sems, indeed, very improbable that meteors fall in at any time > the sun in sufficient quantity to produce dynamical disturances at his surface at all comparable with the gigantic storms ctually produced by hot fluid rushing up from below, and spreadng out over the sun's surface. But now let us consider for a moment the work which must be lone at the sun to produce a terrestrial magnetic storm. Take, or example, the magnetic storm of June 25, 1885, of which Adams gives particulars in his paper of June, 1891 (Phil. frans.. p. 139 and Pl. 9). We find at eleven places, St. Petersburg, Stonyhurst, Wilhelmshaven, Utrecht, Kew, Vienna, Lisbon, San Fernando, Colaba, Batavia, and Melbourne, the horizontal force increased largely from 2 to 2.10 p.m., and fell it all the places from 2.10 to 3 p.m., with some rough ups and lowns in the interval. The storm lasted altogether from about 100n to 8 p.m. At St. Petersburg, Stonyhurst, and Wilhelmsaven, the horizontal force was above par by 0'00075, 0'00088, ind 0'00090 (C.G. S. in each case) at 2.10 p.m.; and below ar by 0'0007, 0'00066, 0'00075 at 3 o'clock. The mean value or all the eleven places was nearly o'0005 above par at 2h. 10m., nd 0.0005 below par at 3h. The photographic curves show hanges of somewhat similar amounts following one another ery irregularly, but with perfectly simultaneous correspondence t the eleven different stations, through the whole eight hours of he storm. To produce such changes as these by any ossible dynamical action within the sun, or in his atmohere, the agent must have worked at something like 160 illion million million million horse-power1 (12 x 1035 ergs per e), which is about 364 times the total horse-power (3.3 × 1033 gs per sec.) of the solar radiation. Thus, in this eight hours of a ot very severe magnetic storm, as much work must have been one by the sun in sending magnetic waves out in all directions rough space as he actually does in four months of his regular at and light. This result, it seems to me, is absolutely conusive against the supposition that terrestrial magnetic storms e due to magnetic action of the sun; or to any kind of dynaical action taking place within the sun, or in connection with rricanes in his atmosphere, or anywhere near the sun outside. It seems as if we may also be forced to conclude that the pposed connection between magnetic storms and sun-spots is real, and that the seeming agreement between the periods s been a mere coincidence. We are certainly far from having any reasonable explanation any of the magnetic phenomena of the earth; whether the it that the earth is a magnet; that its magnetism changes stly, as it does from century to century; that it has somewhat ular and periodic annual, solar diurnal, lunar diurnal, and 11 horse power 7'46 x 109 ergs per second. sidereal diurnal variations; and (as marvellous as the secular variation) that it is subject to magnetic storms. The more marvellous, and, for the present inexplicable, all these subjects are, the more exciting becomes the pursuit of investigations which must, sooner or later, reward those who persevere in the work. We have at present two good and sure connections between magnetic storms and other phenomena: the aurora above, and the earth currents below, are certainly in full working sympathy with magnetic storms. In this respect the latter part of Mr. Ellis's paper is of special interest, and it is to be hoped that the Greenwich observations of earth currents will be brought thoroughly into relation with the theory of Schuster and Lamb, extended, as indeed Professor Schuster promised to extend it, to include not merely the periodic diurnal variations, but the irregular sudden changes of magnetic force taking place within any short time of a magnetic storm. In my Presidential address of last year I referred to the action of the International Geodetic Union, on the motion of Prof. Foerster, of Berlin, to send an astronomical expedition to Honolulu for the purpose of making a twelve months' series of observations on latitude, corresponding to twelve months' simultaneous observations to be made in European observatories; and I was enabled, through the kindness of Prof. Foerster, to announce as a preliminary result, derived from the first three months of the observations, that the latitude had increased during that time by sec. at Berlin, and had decreased at Honolulu by almost exactly the same amount. The proposed year's observations, begun in Honolulu on June 1, 1891, were completed by Dr. Marcuse, and an elaborate reduction of them by the permanent Committee of the International Geodetic Union was published a month ago at Berlin. The results are in splendid agreement with those of the European observatories: Berlin, Prag, and Strasbourg. They prove beyond all question that between May 1891 and June 1892 the latitude of each of the three European observatories was a maximum, and of Honolulu a minimum, in the beginning of October, 1891 that the latitude of the European observatories was a minimum, and of Honolulu a maximum, near the beginning of May, 1892 and that the variations during the year followed somewhat approximately, simple harmonic law as if for a period of 385 days, with range of about sec. above and below the mean latitude in each case. This is just what would result from motion of the north and south polar ends of the earth's instantaneous axis of rotation, in circles on the earth's surface of 7.5 metres radius, at the rate of once round in 385 days. : Sometime previously it had been found by Mr. S. C. Chandler that the irregular variations of latitude which had been discovered in different observatories during the last fifteen years seemed to follow a period of about 427 days, instead of the 306 days given by Peters' and Maxwell's dynamical theory, on the supposition of the earth being wholly a rigid body. And now, the German observations, although not giving so long a period as Chandler's, quite confirm the result that, whatever approximation to following a period there is, in the variations of latitude, it is a period largely exceeding the old estimate of 306 days. Newcomb, in a letter which I received from him last December, gave, what seems to me to be, undoubtedly, the true explanation of this apparent discrepance from dynamical theory, attributing it to elastic yielding of the earth as a whole. He added a suggestion, specially interesting to myself, that investigation of periodic variations of latitude may prove to be the best means of determining approximately the rigidity of the earth. As it is, we have now, for the first time, what seems to be a quite decisive demonstration of elastic yielding in the earth as a whole, under the influence of a deforming force, whether of centrifugal force round a varying axis, as in the present case, or of tide-generating influences of the sun and moon, with reference to which I first raised the question of elastic yielding of the earth's material many years ago. The present year's great advance in geological dynamics forms the subject of a contribution by Newcomb to the Monthly Notices of the Royal Astronomical Society of last March. In a later paper, published in the Astronomische Nachrichten, he examines records of many observatories, both of Europe and America, from 1865 to the present time, and finds decisive evidence that from 1865 to 1890 the variations of latitude were much less than they have been during the past year, and seeming to show that an augmentation took place, somewhat suddenly, about the year 1890. When we consider how much water falls on Europe and Asia |