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STAR TRANSITS BY PHOTOGRAPHY.' THE annoyance that arises from the effects of a "magnitude equation" in transit observations has led to various suggestions for its detection or removal. Screens in front of the object-glass so as to reduce the light of bright stars have been employed with advantage, and various photographic devices arranged with the view of eliminating personal peculiarities have been adopted. But while ingenuity has been active in proposing practical applications and methods, the numerical results have been few. Recently, Prof. S. Hirayama, of the astronomical observatory at Tokyo, has put in practice a contrivance similar to that employed by the Rev. Father Hagen in photographing a star in the focus of the transit telescope. In this method the exposure and occultation of a star is alternately effected by means of a bar, moved in obedience to a clock, so as to give rise to a series of dots along the star trail.

The Tokyo transit was for this purpose provided with a triple object-glass, reducing the secondary spectrum, and specially corrected for photographic rays. The aperture was 13.5 cm., and the focal length 211 cm. The range of magnitude to which the telescope was applicable depended, of course, upon the time of exposure permitted by the occulting bar. As a matter of fact, with a full second's exposure, equatorial stars of the fifth magnitude gave a measurable image. For stars of greater declination than 73° the exposure of one second was too short to divide distinctly the successive impressions from each other. The limitations of the method are thus clearly indicated. For fainter stars it seems necessary to consider the possibility of moving the photographic plate at the same rate as the star, and imprinting on the plate the image of a fixed reticule at known times. The simpler method adopted by Prof. Hirayama recommended itself to him, since the apparatus could be constructed in the workshops belonging to the observatory.

This apparatus consisted of a camera containing the reticule, occulting bar, and the dark slide, which could be inserted in the place ordinarily occupied by the wires and eye-piece. The reticule consists of seven fine lines ruled upon a microscope cover-glass, firmly cemented to a rectangular frame which carries the dark slide. These lines are interrupted for a short distance in the middle of the field so that they shall not interfere with the star images. The centre of the field is marked by two horizontal wires in the ordinary manner. The occulting bar (Fig. 1) is a

FIG. 1.-Showing the bar at rest, in the centre of the field.

thin metal slip about 8 cm. long with a square opening at one end, so as to allow the observer to see the stai enter the field, and to permit him to adjust the instrument so that the transit shall take place behind the bar when in its stationary position. The end of this bar is soldered to the armature of an electromagnetic coil. Whenever the electric circuit is established the bar is lifted up and the star exposed. This circuit is made and broken automatically by contact springs in the standard sidereal clock. The bar 1 "Preliminary Experiments on the Photographic Transit." By S. Hirayama. Annales de l'Observatoire astronomique de Tokyo. Tome iii., 4 fascicule. (Tokyo, 1905.)

consequently operates as an exposing shutter, permitting the cone of light from the star to fall for a longer or shorter period upon the sensitised plate, the period being decided by the contact springs.

The sensitive plate when inserted in the dark slide comes within 0.2 mm. of the lines of the reticule, so that these lines and the image of the star are practically in the same focus. Evidently this distance must be made as small as possible to reduce any error arising from photographic parallax, but the plate can be shifted in its own plane, so that five separate exposures can be made upon the same plate. The advantage thus secured of taking

FIG. 2.-The bar removed, showing the transit of a star; slightly enlarged. five stars on the same plate is somewhat discounted by the fact that no proper adjustment can be made for developing the plates according to the different actinic intensity of the stars.

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The method of observation will be easily apprehended from the description of the apparatus and the character of the results obtained (Fig. 2). The measurement of the plates is not so simple. It is distinctly admitted that to measure a negative is more laborious than to read the fractions of second from chronographic sheet. Theoretically, the beginning of each "break" made by the clock is the exact point to which the reading should refer; but owing to the difficulty of measuring the edges of the dots, due to the want of sharp definition, this plan could not be adopted. The middle of the "break to the middle of the "make" has been taken as the full second. This arrangement, or conventional rule, has probably got over the difficulty arising from the photographic spread, for it seems not impossible but that the want of definition at the edges of the dot, or the distance between two dots, is dependent upon the brightness of the star. But if this source of error is eliminated the author has to regret that the length of the dot depends upon the battery, the spring, the friction, and the moving parts of the apparatus as affected by the variable component of the force of gravity." The weakening of the battery has been constantly provided for, but at present I see no way of escape from all the other disadvantages."

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This admission seems to deprive this peculiar method of observation of much practical benefit. The question that has to be solved is not so much one of relative accuracy as it is of the possibility of eliminating systematic errors. inherent in older and more familiar methods. Looked at as a simple matter of determining the position of a star on a plate at any required moment, the results leave nothing to be desired. In an example worked out in detail it is shown that the error in a single pair of measures is 100175., and the mean error of thirty-two pairs, or what may be regarded as equivalent to a complete transit, 0.002s. The results of the measures of 140 stars, made when the plate was moved with, and against, the direction of diurnal motion, gave for the average value of personal equation +0.0275., the positive sign implying that the time of transit was longer when the plates were measured along the diurnal motion than when measured against it.

But such measures leave the question of a possible error dependent upon magnitude untouched. Unfortunately, the limited range of magnitude and the small number of observations do not permit any very definite conclusion to be drawn. The author presents a table of forty-six stars in which the photographic magnitude varies from 1-2 mag. to 5.5 mag., and gives residuals for each night and the mean residual. The latter is less than 0.05s. in all but two cases out of the forty-six. Further, when these mean residuals are arranged for each star in the order of photographic magnitude, no relation between the two is notice

able. Of the two errors greater than 0-05s., one is +0.072s. and the other -0.060s., and the magnitudes of the two stars are the same, and practically in the middle of the series.

But if there is no indication of a "magnitude equation" there is another circumstance which is not a little suspicious, and interesting as suggestive of the introduction of fresh sources of error. The author has referred to the fact that the mean error of observation can become comparatively large when the photographic image is poor, owing to the small altitude of the star. When the residuals are collected according to the zenith distance of the star, there is some indication of a connection between the two. "There is," says Prof. Hirayama, "a common tendency for the residual error to be least at the zenith, and to increase with the zenith distance." No stars below the pole have been observed, so that there is no means of comparing the results given by stars at small altitudes on opposite sides of the zenith. But many important questions are raised in this paper, and we notice with pleasure that Prof. Hirayama proposes to continue the inquiry. We can assure him that his investigations will be watched with interest in this country.

THE MUSEUMS ASSOCIATION.

THE seventeenth annual meeting of the Museums Asso

ciation was held in Bristol on July 2-5 under the presidency of Dr. W. E. Hoyle, director of the Manchester Museum. The attendance of curators and representatives from various British museums was greater than in any previous year, foreign museums and museum workers being also represented by Geheimrat Dr. A. B. Meyer, of Dresden, Prof. Conwentz, of the Provincial Museum, Dantzig, Prof. Lehmann, of the City Museum, Altona, Mr. H. L. Brakstad, Norwegian Vice-Consul, and others.

The public conference commenced on the morning of July 3 in the Council House, a warm welcome being given to the association on behalf of the city by the Lord Mayor, High Sheriff, and museum committee, after which Dr. Hoyle gave the presidential address, taking as his subject the education of a museum curator. Briefly reviewing the varied training, or lack of training, which many curators have received, Dr. Hoyle divided museums into two great classes (a) museums of art, or institutions in which objects are regarded simply as material for æsthetic contemplation, where they are arranged so that each may be seen to the best advantage and minister to the cultivated enjoyment of the onlooker; and (b) museums of science, in which the object is to exhibit the state of human knowledge on one or more subjects, and to supply means of increasing that knowledge.

mounted specimens, an osteological series, and one in which the main structural features of the animal kingdom would be shown by prepared dissections. Work on similar lines was proceeding in other departments of the museum, and ultimately it was hoped to be able to place at the disposal of any student or visitor all that is necessary in the way of types for the full degree course of any university. Papers were also read by Mr. R. Quick, on the hanging of pictures; by Mr. F. R. Rowley, on a method of displaying coins, and on models of Protozoa; and by Mr. W. W. Watts, on the City plate and insignia.

Wednesday, July 4, was occupied with the discussion of a series of papers on museum cases and fittings, the subject being opened by Dr. A. B. Meyer, of Dresden, who outlined the result of his experiments and researches during the last thirty years upon museum cases. He strongly advocated metal and preferably iron cases, which could be made dust-proof, elegant in appearance, and not more costly than wooden cases. Dr. Meyer's remarks followed by a paper from Mr. F. A. Lucas, of Brooklyn Museum, and one by Dr. Lehmann on a simple practical dust-proof case in the Altona Museum. Mr. Bantry White, of the Dublin Museum of Science and Art, exhibited an iron museum case built in that museum's own workshops, which was very efficient, dust-proof, and not costly.

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A remarkable cabinet case, with changing trays each of which could be brought into view in turn by mechanical means, was exhibited and explained by the Rev. S. J. Ford. Mr. A. M. Rodger exhibited case fittings from the Perth Museum, and Mr. Woolnough, of Ipswich, complete models of cases it was proposed to introduce into the museum at that town. The lighting of museum cases was dealt with by Mr. Thos. White, of London. Dr. F. A. Bather explained the character of some cases in the British Museum, and illustrated his remarks, as did other speakers, by photographs and drawings. Mr. J. Osborne Smith also dealt with the same subject, and exhibited the original drawings and plans of many of the more recently made cases. Owing to the interest and importance of the subject the session was continued in the afternoon until four o'clock.

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Thursday was occupied by a paper on the American Museum of Natural History, by Dr. H. C. Bumpus; by a on wall diagrams to illustrate prehistoric archæology, from Prof. Conwentz; a paper on the Altona room in the Arts and Crafts Exhibition, Dresden, designed to show how the form of animals is the concrete expression of adaptation to their suroundings; and one on the construction and management of museums of art, by Mr. B. Ives Gilman.

The afternoons and evenings of July 3 and 5 and the whole of Friday, July 6, were occupied by visits to the zoological gardens at Clifton, a conversazione at the Museum and Art Gallery, visits to the stone circles at Stanton Drew, the ancient British lake village near Glastonbury, the Glastonbury Museum, and the Cheddar Gorge and Caves. The meetings were well attended throughout, and a highly successful conference was brought to a close on Saturday last.

Confining his observations to the character of training required for curators of science museums, the president urged the necessity of a fair preliminary training in manual industry and the knowledge and use of tools, and afterwards a technical and scientific training in those subjects underlying the future work of the embryo curator. As subjects necessary to be studied because of their close relation to museum collections were enumerated the natural sciences, mineralogy, geology, biology, including in the latter term botany, zoology, anthropology, and ethnology. As sciences more nearly concerned with the acquisition, registration, preservation and exposition of museum collec-AT tions were instanced the rudiments of mechanical engineering, physics, and chemistry. As a kind of post-graduate course, the necessity of visiting and studying the nature and methods of work of various museums was strongly insisted upon.

Alderman W. R. Barker, chairman of the Museum and Art Gallery committee, laid before the association a paper he had prepared tracing the rise and progress of the Bristol Museum from its inception in 1808 to the present union of museum and City Art Gallery.

Mr. H. Bolton, curator of the Bristol Museum, followed with a paper describing the general character of the collections, and the steps which had been taken to bring the mode of exhibition and usefulness of the museum contents up to modern requirements, mentioning that it was the intention of the committee to introduce a type-series of

THE METEOROLOGY OF THE FREE

ATMOSPHERE.

the request of the council of the Royal Society of Edinburgh, M. L. Teisserenc de Bort gave an address on the meteorology of the free atmosphere at the meeting of the society on May 21. Subjoined is a summary of his lecture.

The methods for sounding the atmosphere employed at the present day have been in our possession but a few years. The kite, carrying self-registering apparatus, was introduced by the Americans about fifteen years ago; the sounding balloon dates but twelve years back. The use of balloons, furnished with registering apparatus, was proposed by Lemonnier, a French physicist, at the end of the eighteenth century; but they were actually employed for the first time by the Brothers Renard, and especially by MM. Hermite and Besançon, whose first observations go back to 1893.

Observations of great interest had already been made on

mountains.

To these are now added observations made in air altogether free.

The distribution of the barometric pressure at a distance of several thousand metres above the ground was first examined, and maps were shown giving the isobars at 4000 metres as calculated from the pressure and temperature on the surface of the earth.

M. Teisserenc de Bort has carefully verified that the pressure in free air diminishes in accordance with the barometric formula. For that purpose he determined the the heights of a large number of balloons by observing them with two theodolites. On the average the heights thus observed agree with those deduced from the barometers carried by the balloons to within 2 or 3 millimetres of barometric pressure for a height of 4000 metres. The maps of the isobars at 4000 metres show that most of the areas of high and of low pressure observed near the ground become effaced as we rise in the air, and give place to a pressure distribution of a much simpler kind, viz. a maximum of pressure all round the earth in the tropical regions, and low pressures at the poles. The average direction of cirrus clouds is in harmony with these conditions.

As regards the distribution of temperature, the following conclusions were established :

(1) Even at a height of several thousand metres above the ground there is, contrary to what had been thought, a very sensible variation of temperature from winter to summer, the divergence of temperature between the coldest and the hottest month being 9° C. at 10 kilometres height. (2) After it had been noticed that the rate of fall of temperature increases with the height above the ground, it was naturally supposed that temperatures at great heights in the air were extremely low. But sounding balloons dispatched from the Trappes Observatory have proved that, after a certain height, varying from 9 to 14 kilometres, the fall of temperature ceases altogether-another fact that was wholly unexpected.

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(3) The zone where the temperature ceases to fall, called "isothermal zone, " is situated nearer the ground (8 to 9 kilometres in certain places) with low pressures, and further from the ground (about 12 or 13 kilometres) above high-pressure areas.

(4) As a general rule, it is colder in the upper part of an anticyclone than it is at a corresponding height above low pressures, but the contrary holds at medium heights of about 5 kilometres. The absolutely lowest temperatures are observed near high pressures. A temperature of -73° has been observed several times at Trappes, and recently as low as -80° in Austria.

(5) Balloon flights made daily for a week or more at a time, in different years and at different seasons, have shown that at intervals of a few days the atmosphere experiences variations of temperature which are much more important high up than on the ground. At a height of 11 kilometres variations of 15° to 20° are often observed at a time when variations of only 2° to 3° are found near the ground.

It is believed that the arrest of the decrease of temperature is connected with the cessation at a certain height of movements of the air having a vertical component, the air then having movements which follow the isobaric surfaces. There is no longer any temperature variation due to expansion or compression of the air.

It has been demonstrated, alike by calculation of the isobars and by the flight of balloons, that most of the depressions which appear near the ground as complete atmospheric vortices suffer deformation as the height increases, and in their northern part lose themselves in the great polar vortex; so that, at a certain height (4 to 7 kilometres), east and north-east winds are no longer found to the north of a depression, and the isobars at this height form a handle attached to the low-pressure areas of northern latitudes. On the front of a depression its characters remain distinct to the top; a sheaf of ascending air reaches the height of cirrus cloud, and then spreads over the barometric maxima to east and south-east.

M. Teisserenc de Bort exhibited his very light, compact self-registering apparatus for measuring the temperature, pressure, and humidity in the upper regions of the atmosphere. Dr. W. N. Shaw, F.R.S., expressed the indebtedness of meteorologists to M. Teisserenc de Bort, whom he

had come all the way from London to hear. After referring to the main points of the address, Dr. Shaw directed attention to another important line of research for which M. Teisserenc de Bort has fitted up a fish carrier, acquired at Hull, with the aid of which he is investigating at the equator the problem of the upper trade winds.

INTERNATIONAL SCIENCE

an address delivered to the British Association at its IN Belfast meeting in 1902 I expressed the opinion that meteorology might be advanced more rapidly if all routine observations were stopped for a period of five years, the energy of observers being concentrated on the discussion of the results already obtained. I am glad to say that meteorologists have taken this remark as being meant seriously, and its echoes still reach me from distant parts of the earth. They disagree with me, but their disagreement is of the apologetic kind. I do not wish to retract or to weaken my previous statement, but merely to qualify it now to the extent that it is only to be applied to twodimensional meteorology. There is a three-dimensional meteorology as far removed from the one that confines itself to the surface of the earth as three-dimensional space is from a flat area. Three-dimensional meteorology is a new science, which at present requires the establishment of new facts before their discussion can properly begin. The extension of our range of observations by kites and balloons is of comparatively recent origin. Mr. Archibald in this country was one of the pioneers of meteorological investigation by means of instruments attached to kites. In the United States Mr. Rotch, having established a separate observatory, succeeded in convincing scientific men of the great value of the results which could be obtained. M. L. Teisserenc de Bort, who established and maintained an observatory for dynamic meteorology at Trappes, near Paris, rendered similar services with regard to pilot" or unmanned balloons carrying autographical instruments. The aeronautical department of the Royal Prussian Meteorological Institute, with Dr. Assmann at its head, under the direction of Prof. von Bezold, also made a number of important contributions in the early stages of the work. Prof. Hergesell, of Strassburg, similarly made numerous experiments, and chiefly through the efforts of those whose names have been mentioned, and more especially Prof. Hergesell, an international agreement has been secured by means of which kite and balloon ascents are made in several countries on the first Thursday in each month, and on three consecutive days during two months of the year. A large station for aëronautical work was recently established at Lindenberg, near Berlin, where kites or balloons are sent up daily for the purpose of securing meteorological records. The greatest height yet reached was during the ascent of November 25, 1905, when by means of several kites sent one after another on the same wire, the upper one rose to an altitude of 6430 metres, almost exactly four miles. Owing to want of funds this country could until recently only participate in this work through the individual efforts of Mr. Dines, who received, however, some assistance from the British Association and the Royal Meteorological Society. The reconstruction of the Meteorological Office has made it possible now for Mr. Dines's work to be continued as part of the regular work of the office, and further stations are being established. Mr. Cave carries out regular ascents at his own expense at Ditcham Park, and through the cooperation of the Royal Meteorological Society and the University of Manchester, assisted by a contribution for apparatus from the Royal Society Government Grant Fund, a regular kite station is being established on the Derbyshire moors.

The International Committee which collates the observ ations is a commission appointed by a union voluntarily formed between the directors of meteorological observatories and institutes of countries in which regular observations are taken. The meeting of directors discusses schemes of observations and encourages uniformity.

If I mention a few of the difficulties which stand in the way of a homogeneous system extending over Europe, I 1 Discourse delivered at the Royal Institution on Friday, May 18, by Prof. Arthur Schuster, F.R.S. (Continued from p. 237-)

do it in the hope that it may perhaps ultimately assist in removing some of them. It is obviously desirable that the charts, which are intended to show the distribution of pressure and temperature, should be derived from observations made at the same hour. Germany observes at eight o'clock of central European time, and France observes simultaneously (or nearly so) by choosing seven o'clock Paris time for its readings. We observe at eight o'clock Greenwich time, which is an hour later. It is the great desire of Continental meteorologists that our standard hour should be seven o'clock; and what prevents it from being so? Chiefly and absolutely the additional cost which the Post Office must claim for the transmission of telegrams; because messages transmitted before eight o'clock are subject to an additional charge of one shilling, which may be claimed by the postmaster, the claim being possibly increased to two shillings when the postmaster and telegraphist are different persons. This is prohibitive, but it does not exhaust the inconvenience of the additional charge. For the purpose of weather forecasting it is clearly necessary that telegrams should be received as early as possible by the Meteorological Office. But the eight o'clock rule delays telegrams from some Irish stations, because eight o'clock by Dublin time is 8.25 by Greenwich time, and therefore Irish telegrams may have to wait until nearly half-past eight if they are to be transmitted without extra charge.

While the international organisation of meteorology is well on its way, though difficulties such as those I have mentioned may temporarily retard it, another question not altogether disconnected with it has been raised by Sir John Eliot. This is the establishment of an institution devoted to the collective study of meteorological problems affecting all parts of the British Dominions. It is true, not only in this, but also in other matters, that in order to take our proper position in international work it is necessary that we should set our own house in order, and we must give Sir John Eliot's proposals our hearty support. If I do not enter further into this question it is because I am to-day dealing more especially with problems which go beyond the limits of the Empire. I assume the existence of a national organisation, but lay stress on the insufficiency of this limitation.

The importance of the subject, however, may be my justification if I direct your attention for a moment to the meteorological question as it presents itself in India. We all know and realise the vital importance of the rainy season, and the benefit which the native population would derive if it were possible to predict, even if only imperfectly, the setting in of the monsoon. It appears that Dr. Walker, the present director of observatories in India, recently obtained very encouraging results in this respect. According to his investigations, a forecast of the monsoon may be derived from a knowledge of the weather during preceding months in different parts of the world. Thus a heavy rainfall in Zanzibar in May is followed by a weak monsoon, while a pressure deficiency in Siberia during the month of March indicates a probable deficiency of rain in India during the following August. I need not insist on the importance of these results, which at present are purely empirical, and require further confirmation; but it is quite clear that for the successful prosecution of these inquiries political boundaries must be disregarded, and a system of intercommunication organised between countries chiefly concerned. Dr. Walker informs me that he has successfully arranged for telegraphic reports to be sent to him at the beginning of June from six different stations in Siberia. It is hoped that this cooperation, which was unavoidably discontinued during the late war, may now be re-established.

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The course of international organisations does not always run smoothly. The efforts made toward cooperation in earthquake records have unfortunately led to differences of opinion, which have hitherto prevented a truly international system being formed; and if I give a short historical account of the circumstances which have led up to these differences it is only in the hope that this may help to remove them. The scientific investigation of earthquakes may be said to have begun when British professors of physics, engineering, and geology were appointed at the

Imperial College of Engineering in Tokio. Some of them, on returning home, succeeded in interesting the British Association in the subject. Ever since 1880 that association has been an active supporter of seismic investigations. The much disturbed region of the Japanese island was naturally the first to be studied; but in 1895 Prof. Milne, as one of the secretaries of the committee, issued a circular directing attention to the desirability of observing waves which have travelled great distances, and some months later, Dr. E. v. Rebeur-Paschwitz, of Strassburg, drew up suggestions for the establishment of an international system of earthquake stations. To this scheme Prof. Milne and other members of the British Association committee gave their approval. The cooperation which thus seemed so happily inaugurated was broken by the unfortunate death of its originator. Circumstances then arose which compelled the British Association committee to go its own way. Under its direction a system was established which now includes about forty stations distributed all over the world. But the needs of different countries are not, and were not meant to be, completely satisfied by this organisation.

There is always a certain number of earthquakes having purely local importance and requiring discussion from a purely local point of view. For the purpose of such discussion relating to the disturbances which chiefly affect Central Europe, the Union (so-called Kartell) of the Academies of Vienna, Munich, Leipzig, and Göttingen formed a committee and did excellent work. In the meantime Prof. Gerland, who had succeeded Dr. RebeurPaschwitz at Strassburg, had personally invited a number of friends interested in the subject to a conference at Strassburg with the object of forming an international association. This was followed in 1903 by a formal conference called by the German Government, at which Great Britain was represented by Sir George Darwin and Prof. Milne. This conference drew up a scheme for an international association, and a large number of countries, including Russia and Japan, joined. Strassburg was selected as the seat of the Central Bureau. The matter came up for discussion at the meeting of the International Association of Academies, which was held in London in the year 1904, and a committee was appointed for the purpose of suggesting such modifications in the constitution of the seismic organisation as might bring it into harmony with the views of the associated academies. This committee, over which I had the honour to preside, met at Frankfort, and recommended a number of important changes, which were unanimously accepted by the second seismic conference held last summer in Berlin. In consequence of this acceptance it appears that Italy and the United States joined the seismic association, while England declared its willingness to join under certain conditions, of which the simultaneous adhesion of France was one. The following summary of the States which have joined, and their population, is copied from the official report of the last meeting

at Berlin:

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It was decided at the Berlin meeting that Prof. Kövesligethy, of Budapest, should be secretary, and Prof. Palazzo, of Rome, the vice-president, of the International Seismic Association. Prof. Gerland had already previously been designated as director of the Central Bureau. The office of president of the association was left vacant until the final decision of Great Britain as to its adhesion had been settled. There the matter stands for the present.

The disastrous results of recent earthquakes and volcanic eruptions have directed increased attention to the subject. Its thorough investigation is indeed likely to yield important information on the interior constitution of the earth. A hearty cooperation to obtain and circulate the material for a detailed discussion cannot fail to bear fruit, and, even though there may be legitimate grounds for dissatisfaction at the manner in which a particular scheme has been organised, I must express my own opinion that at the present moment the permanent interests of this country would be best secured by our joining the association and helping to direct its work in a manner which would assis rather than hamper the present organisation of the British Association.

Although time is running short, I am perhaps in private duty bound not altogether to pass over in silence an organisation which has its central bureau in my own laboratory at the University of Manchester. This is a union for the observation of solar phenomena. Called into being chiefly by the energy of Prof. Hale, this association is perhaps unique in two respects. It aims more directly at conducting research work than is the case with other unions, and in so far may run the danger of hampering private efforts. This danger has, I believe, been well guarded against by the constitution adopted at the first meeting of the conference held last September at Oxford. The second peculiarity referred to is that it works a central bureau, a computing bureau (under the direction of Prof. Turner), and is going to publish Transactions without any funds beyond those doled out to it by charity. Its vitality will, I hope, help it to overcome its initial troubles. Its ambitious programme includes a definite agreement on the standard of wave-length and investigations on the permanence or variability of solar radiation.

This latter question is of considerable interest to meteorologists, and comes, therefore, within the purview of the directors of meteorological observatories, who have also, under the presidency of Sir Norman Lockyer, established a commission charged with its discussion. An arrangement has been made securing cooperation between the two bodies, the Solar Union leaving out of its programme the difficult question of the relationship between sun-spot variability and meteorological phenomena.

Although an unnecessary overlapping of two separate enterprises has in this instance been avoided, such overlapping constitutes a certain danger for the future, as the problems of geo-physics-for the investigation of which international associations are specially marked out-are so intimately connected with each other that a homogeneous treatment would seem to require a central body supervising to some extent the separate associations. Such a central body may be found in the International Association of Academies, which promises to play so important a part in scientific history that a short account of its early history may be of interest. The Kartell of some of the German academies and that of Vienna has already been referred to. In discussing the utility of its deliberations, Prof. Felix Klein, of Göttingen, first mentioned to me the idea that an association of a similar nature would be likely to prove of still greater value, if formed between the scientific and literary academies all over the world. In consequence of this conversation I tried to interest the Royal Society in the subject; and in order to obtain further information Prof. Armstrong and myself attended privately, though with the knowledge and consent of the council of the Royal Society, the meeting of the Kartell which was held at Leipzig in the year 1897. In the following year the two secretaries of the Royal Society, Sir Michael Foster and Sir Arthur Rücker, together with Prof. Armstrong and myself, attended the Kartell which then met at Göttingen.

The secretaries were impressed by the great possibilities of the scheme, and the council then took the initiative and approached the academies of Paris and St. Petersburg, which both returned favourable answers.

In consequence of the correspondence between these learned societies, the Royal Academy of Berlin, in conjunction with the Royal Society of London, issued invitations for a general conference to be held at Wiesbaden on October 9 and 10, in the year 1899.

The following were represented at this meeting, at which the statutes of the new association were agreed upon :-

The Royal Prussian Academy of Sciences of Berlin.
The Royal Academy of Sciences of Göttingen.
The Royal Saxon Academy of Sciences of Leipzig.
The Royal Society of London.

The Royal Bavarian Academy of Science of Munich.
The Academy of Sciences of Paris.

The Imperial Academy of Science of St. Petersburg.
The National Academy of Science of Washington.
The Imperial Academy of Sciences of Vienna.

The unanimity of the meeting may be judged from the fact that a working constitution, which subsequent experience proved to be eminently effective, was finally arrived at on the second day. Many distinguished men took part in the discussions; amongst them Prof. Simon Newcomb and the late Prof. Virchow may be specially mentioned.

Although the Berlin Academy had never joined the German Kartell, the first idea of a wider association seems to be due to a distinguished member of that body, the historian Mommsen, who, though of advanced age, was able to be present at the first regular meeting of the associ. ation, which was held at Paris on April 16-20, 1901. in addition to the societies which took part in its foundation. the following form part of the association, and were represented at Paris :

The Royal Academy of Sciences of Amsterdam.

The Royal Belgian Academy of Sciences, Arts and

Letters.

The Hungarian Academy of Sciences.
The Academy of Sciences of Christiania.
The Academy of Sciences of Copenhagen.

The Academy "des Inscriptions et Belles Lettres" of the Institut de France.

The Academy of Sciences, Morales et Politiques of the Institut de France.

The Royal Society "dei Lincei " of Rome.
The Royal Swedish Academy of Sciences.

This meeting is not likely to pass out of the memory of those who took part in it. Its importance was enhanced by the social functions which were held in connection with it, and which included a luncheon given by President Loubet at the Elysée, a banquet given by the Conseil Municipal, and a special performance at the Théâtre Français. The subsequent triennial meeting of the academy, which was held in London in 1904, passed off not less brilliantly. The representatives of the learned societies were received by their Majesties at Windsor, and the Lord Mayor invited them to dinner at the Mansion House. Social entertainments, though welcome as marking the importance of the occasion, are not allowed to interfere with the very substantial work which is being done at these meetings. The list of subjects which were included in the discussion of the London assembly may give an idea of the range of activity of the association. A permanent committee is charged with the investigation of the functions of the brain, others deal with questions of atmo spheric electricity, and of the measurement of magnetic elements at sea. An important proposal to carry out an exact magnetic survey along a complete circle of latitude is under discussion. The section of letters dealt with the mutual arrangements between libraries regarding the interchange of manuscripts, approved the intended edition of the Mahabharata, and considered a proposal to construct a new Thesaurus of Ancient Greek. The association also took cognisance of and received reports on independent

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