arrived at that it is not caused by any special bacterium, but by several different species of common occurrence on mulberry leaves.

WE have received part ii. of the reports of the commission appointed for the investigation of Mediterranean fever, part i. of which has already been noticed in NATURE (May 4, p. 17). Dr. R. W. Johnstone deals with the sanitary circumstances and prevalence of the disease in the Maltese Islands, but is unable to give any definite pronouncement on the mode of human infection. The facts do not indicate that dust, personal contact, or excretal pollution play an important part in the spread of the disease. Staff-Surgeon Bassett-Smith, R.N., details experiments on the saprophytic life of the Micrococcus melitensis, and Dr. Eyre on the virulence of this organism for the guinea-pig.

THE Bulletins of the Bureau of Government Laboratories, Manila, several of which have from time to time been noticed in these columns, always contain matter of interest. No. 20, in five articles, discusses various diseases occurring in the Philippine Islands, and in No. 21 Dr. Strong deals with certain questions relating to the virulence of micro-organisms and their immunising powers. The conclusion is arrived at that a virulent cholera spirillum possesses a greater number of bacteriolytic and agglutinable haptophore groups, or these groups are endowed with a greater binding power for uniceptors and amboceptors than the avirulent. That is to say, virulent cholera microbes have a greater capacity than avirulent microbes for uniting with living cells and their products.

AN article on roses by Mr. Jekyll in the April number of the Bulletin of the Department of Agriculture, Jamaica, warns growers against attempting to grow hybrid perpetuals in the island. First place is assigned to the tea and noisette sections, which produce good results except in so far as the sun is too strong for some, and a good selection of suitable roses may be made from the list which is given.

A FLORA of the islands of Margarita and Coche, lying off the coast of Venezuela, is being prepared by Mr. J. R. Johnston, but meantime he has published a list of new plants from these islands in the Proceedings of the American Academy of Arts and Sciences (April). A new genus, Anguriopsis, is formed having affinities with the cucurbitaceous genus Anguria. Among the new species are a Bactris-a palm with handsome foliage-two new orchids, and several trees, including a Capparis, a Cæsalpinia, and a Casearia. The new species are for the most part additions to genera or sections of the genera which are confined to tropical America.

ONE of the most fruitful lines of recent research in botany has been concerned with the investigation of fossil seeds, of which several species of Lagenostoma are the best known. The evidence in favour of referring these seeds to certain vegetative portions of Carboniferous plants, formerly regarded as fern fronds, formed the subject of Dr. Scott's presidential address to the Royal Microscopical Society, which is published in the April number of the Journal. The cycadofilicinean position assigned to Lyginodendron Oldhamium, which shows a sphenopteris type of foliage, was confirmed by the evidence which connected the same plant with Lagenostoma Lomaxi. Mr. Kidston's discovery of the fructification of Neuropteris heterophylla fixed the seed to another typical fern-frond,

and recent research points to the production of winged seeds by a species of Adiantites.

both

are

In a sketch of the geology of Upper Assam (Records Geol. Surv. India, xxxi., part iv.) Mr. J. Malcolm Maclaren describes the region as a great plain, 320 feet to 500 feet above sea-level, bounded on the north-west by the eastern Himalayas and on the south-east by the Patkai ranges, while the head of the valley is closed in by the crystalline and metamorphic rocks of the Miju ranges. Upper Tertiary sandstones occur at a considerable height (maximum 6900 feet) on the Patkai and Himalaya ranges, but have not been observed anywhere on the heights of Miju. Attention is directed to the general uptilting and reversed faulting of the Tertiary rocks on either side of the great plain, and to the deflection in the trend of the Patkai range where it abuts against that of Miju. These features are attributed to earth stresses during the formation of the mountains. The author concludes that the Patkais and Himalayas, in their later growth at least, are of contemporaneous development, and that orographically and geologically distinct from the great meridional mountain system of Upper Burma, Tibet, and western China. In another article Mr. Maclaren deals with the auriferous occurrences of Assam. Gold was there worked in ancient times, and it is distributed in extremely small percentages throughout the alluvial gravels of the Brahmaputra; but the author is of opinion that only two or three localities are worthy of further prospecting, and that these are likely to yield comparatively small results. He believes that in Assam, as in most other parts of India, the climatic conditions that make for concentration of gold have always been absent. There never has been that even flow of waters confined within well-marked banks, that after a lengthened period results in a separation and local concentration according to specific gravity of the riverborne minerals in "leads" and "runs." On the other hand, there have been annual floods, varying so quickly in height, velocity, and direction that the slight local concentration of one year has been effaced by succeeding floods.

WE have received vol. ii. of the year-book of the AustroHungarian Meteorological Observatory of Agram for the year 1902, a large folio publication containing fifty pages of tables giving detailed and summarised observations and results at a number of stations in Croatia and Slavonia. The size of the work is somewhat unwieldy, but the tables are very legible, and have been carefully prepared on the plan of the international scheme for meteorological publications. Hourly readings, and hourly and daily means, are given for Agram.

THE recently published annual Journal of the Scottish Meteorological Society (third series, Nos. 20 and 21) contains an interesting discussion of the rainfall of the Ben Nevis observatories, by Mr. Andrew Watt. The measure ment of precipitation on the summit was attended with great difficulties; the high wind velocities, at an altitude of 4400 feet, made the registration of snow (which mostly falls between October and May) and even of rain somewhat uncertain. The tables show the falls at the upper and lower stations for the nineteen-year period 1885-1903. The average annual rainfall at the summit was 1008 inches, and that at the foot 78.6 inches; in individual years the amounts varied from 49 per cent. above to 33 per cent. below the mean values on the summit, and from 45 per cent. above to 23 per cent. below at the lower station.

been published by Messrs. C. Arthur Pearson, Ltd. Dr. Lankester has made important additions to his book descriptive of the compound microscope and its accessories, and has incorporated a chapter by Mr. F. Kitton on the polariscope and its uses. Dr. John Matthews has edited the second book, and has made several alterations and additions, among the latter being a prefatory chapter dealing with preliminary histological manipulation.

THE Bulletin de la Société des Naturalistes de Moscou (1904, Nos. 2 and 3) contains the following papers :Four notes on the crystalline forms and optical properties of various salts.-On the theory of endosaprophytism with lichens, by A. Elenkin. A defence of the latter as against the mutualistic theory, with a bibliography of the literature of the subject (in German).-The Jurassic corals of the Sudagh, by A. Missuna (with plates). In a total of 108 species, 46 are new for the Crimea, and 14 new species are described. The Crimean coral-fauna has its nearest relative in the Jurassic fauna of Switzerland (this paper is in German). Materials for the algology of Lake Baikal, by V. Dorogostaisky (with a plate). Results of a two years' study of the algæ in Lake Baikal and its affluents. A list of 350 species is given, a few of them being new (this paper is in French).-History of development of the excre tory system with the Amphibiæ, D. P. Filatow (in German, with a plate). The same number contains a fine portrait of Prof. T. A. Bredikhin, and a biographical sketch of the late Moscow astronomer, including a sketch of his theory of comet tails, by P. K. Sternberg.

Venus at maximum brilliancy.
13h. 3m. Minimum of Algol (B Persei).

8h. 22m. to 9h. 24m. Moon occults / Virginis
(mag. 4'9).

13. Saturn. Outer major axis of outer ring = 40" 87; outer minor axis of outer ring = 6" 03.

9h. Mars in conjunction with moon, Mars 6° 14' S. 9h. 52m. Minimum of Algol (8 Persei).

Venus. Illuminated portion of disc=0.365; of Mars =0'938.

15h. Sun enters Cancer, Summer commences. 22h. Saturn in conjunction with Moon, Saturn 1° 29' S.

23h. Uranus in opposition to the Sun.

14h. 48m. to 16h. 33m. Transit of Jupiter's Satellite III. (Ganymede).

14h. 10m. to 15h. Im. Moon occults 0 Tauri (mag. 3.6).

14h 15m. to 14h. 56m. Moon occults 61 Tauri (mag. 3'9).

A REMARKABLE VARIABLE STAR.-In a note published in No. 4017 of the Astronomische Nachrichten Prof. E. C. Pickering states that the light-changes of the variable star 154428, R Coronæ Borealis, are unlike those of any other known variable. A series of observations, made by Mr. Leon Campbell, showed that during the period MarchSeptember, 1903, the magnitude underwent remarkable changes between the limits 60 and 9.4. Since then until March of the present year it remained stationary at 6.0 m. The unusual character of the changes during April and May is shown in the following table :

It is easily recognised on the Harvard " Map of the Sky," plate No. 18 (118.75), and is nearly equidistant from 7, 8,

and Coronæ.

RADIAL VELOCITIES OF THIRTY-ONE STARS.-For the past ten years line-of-sight observations have been made at the Emerson McMillin Observatory (Columbus, Ohio), but Prof. Lord has now arrived at the conclusion that, as so many better equipped observatories, situated in more favourable atmospheres, are engaged in this work, it seems advisable to discontinue the observations there and direct the available resources into some other channel of research for which they are better equipped. Consequently he has collected all the results obtained during the decennary, and has published them in No. 4, vol. xxi., of the Astrophysical Journal. Complete catalogues of the plates taken and of the standard lines employed, and the collected results, are embodied in his communication. Amongst the thirty-one stars dealt with there occur a, Cassiopeiæ, Aldebaran, a Arietis, a Persei, Capella, Pollux, Dubhe, Arcturus, 8 and y Cygni, and 8 Cephei.

MAGNITUDES Of Nova PerseI AND NOVA GEMINORUM.-In No. 4017 of the Astronomische Nachrichten Prof. A. A. Nijland publishes the results of a number of magnitude observations of Novæ Persei and Geminorum. The observations of the former covered the period November 15, 1901, to January 13, 1905, and the figures given show frequent increases of brightness, which were, however, very small. A gradual decrease of magnitude underlies these minor fluctuations, and on January 13 the Nova was of magnitude

10.74.

The Nova Geminorum observations extended over the period March 27, 1903, to December 30, 1904, and on the latter date the magnitude recorded was 13.3, more than 2.7 magnitudes fainter than Nova Persei on the same date.

OXFORD UNIVERSITY OBSERVATORY.-Prof. Turner's report of the work done at the Oxford University Observatory during the twelve months ended April 30 informs us that the Oxford work in connection with the International Astrographic Catalogue is at last within measurable distance of publication. The measures and reductions were completed last year, and the whole thing is now ready to print. What is still more satisfactory, the university has set aside 1000l. for this purpose, and this is to be supplemented by a similar contribution from H.M. Government.

The stereo-comparator has been used to compare some of the newer with some of the older plates, but, so far, nothing of importance has been discovered; more time will be given to this work when the coming eclipse is past and the Oxford contribution to the International Catalogue is safely in the press. As some of the earlier plates for the catalogue are less satisfactory than the later ones, they are being duplicated, and the new ones are being measured and reduced as opportunity occurs. An expedition from the observatory, comprised of Prof. Turner and Mr. Bellamy, will observe the total solar eclipse of August next in Egypt.

VARIATIONS OF LATITUDE.-The provisional results of the work accomplished by the International Latitude Service during 1904 are given by Prof. T. Albrecht in No. 4017 of the Astronomische Nachrichten. The results obtained at the six stations employed in the service are grouped, and the variation of the momentary from the mean pole during the years 1900-4 is graphically shown. From this curve it appears that the year 1904 was marked by a diminution in the amplitude of the variation.

NEW REFRACTION TABLES.-Appendix ii., vol. iv. (second series), of the Publications of the U.S. Observatory contains a number of reduction tables for transit-circle observations compiled under the direction of Prof. Eichelberger. All of them, except the refraction tables, are of no use at any other observatory, but these may be found useful by other transit observers. They consist of nine separate tables, in which the logarithms of the various arguments necessary for determining the exact refraction correction for each minute of apparent zenith distance from o° to 85° are given. An example which precedes the tables clearly illustrates the method of using them. The tables are based upon those of Pulkowa.

and in many regions is, paid to the region from which the prevailing winds come, due consideration being given to 'the particular barometric system of which the wind forms part.

From the above the important functions of islands conveniently situated become obvious. It is not, however, every country bordering on the ocean that is blessed with such an island in the direction of the prevailing wind, and the British Isles, in consequence, suffer very much from this very defect. In Great Britain the main rain-bearing wind is that from the south-west. In summer this forms part of a large anticyclonic system situated in mid-Atlantic towards the south-west (see Fig. 1), while in winter it is a portion of a cyclonic system the centre of which is near Greenland (see Fig. 2). With no islands in the track, the only meteorological information that is at once useful is that which can be gathered from messages sent by the Marconi system of wireless telegraphy from steamers en voyage. British weather forecasters are thus undoubtedly heavily handicapped by the lack of some permanent outlying source of information in this region.

river flows producing floods and much damage, an average amount of water for successful crop production, or a deficiency of rain which might result in a disastrous drought and possibly a famine. In the case of storms, a means will be afforded of saving many lives and ships, and also, probably, much property ashore.

The study of the weather, therefore, should be fostered to its fullest extent, and every advantage should be taken of means which will bring us nearer the goal of satisfactory forecasting.

Investigations carried out during the last decade have indicated the importance of each weather bureau extending its area of inquiry beyond the region for which it is making its forecasts. Needless to say, many of these institutions have for some years been in telegraphic communication with outlying stations. Thus, for instance, the Indian Meteorological Service receives information from a station so far distant as Mauritius, while the U.S. Weather Bureau utilises valuable observations by telegraph from stations in the West Indies, Azores, Europe, &c.

Mention has already been made of the use of islands by the United States and India. The latter is particularly fortunate, for Mauritius, Seychelles, Chagos (marked with dots in the figures), and other islands are all conveniently situated to render information if necessary.

Another region which very probably would gain considerably by utilising observations made at island stations is South Africa.

In a previous number of this Journal (vol. lxxi. p. 342, February) Mr. E. Hutchins, Conservator of Forests, Cape Town, gave an excellent account of the general weather conditions in this region. He pointed out that South Africa

It is important to bear in mind that rain-bearing winds are those that have passed over large stretches of water, and that the rainfall of a country is deficient or well supplied with this commodity according to its geographical position in relation to the oceans or inland seas, mountain ranges, and the prevailing winds. It is for these reasons that the nearer the coast is approached from the centre of any continent, the greater becomes the rainfall. Thus, for instance, the interior of Australia, the Sahara, the Arabian Desert, Tibet, &c., are all very dry

areas.

For forecasting purposes, therefore, attention should be,

'roaring forties' of mariners." He further directs attention to the need of distinguishing between these two weather systems, which play distinct parts in the meteorology of this region. A study of the accompanying two figures will indicate the importance of the islands of Tristan d'Acunha and Gough (indicated by a black dot towards the south-west), and also of Mauritius (the dot east of Madagascar). The two former islands lie in the wind system pertaining to the anticyclonic (high-pressure) area on the west, the centre being indicated by the letter H, while Mauritius, situated to the east of South Africa, is in the south-east trade area in the system formed by the high-pressure (anticyclonic) region, the centre of which is marked also with an H.

By observing the general trend of the air currents indicated by the large arrow, it will be seen that for the winter season in South Africa (Fig. 1) meteorological observations made in either Tristan d'Acunha or Gough Islands would undoubtedly render valuable aid to the

weather forecasters.

In the case of the summer months (Fig. 2) there is no conveniently placed island that could furnish equal assistance, but it seems very possible that use could be, and most probably has been, made of the observations at Mauritius for determining the strength of the south-east trade current which impinges on the African coast at this time of year. For forecasting purposes Mauritius, and possibly Rodrigues, would have greater value for regions further up the African coast.

Unfortunately, the Amsterdam and St. Paul islands (marked with one dot) lie too far south and east to serve as useful outlying stations for South Africa. On the other hand, these islands should be undoubtedly utilised by the Australians.

An examination of the accompanying figures indicates the relative positions of the Australian continent and this large southern Indian Ocean wind system. These islands will thus be seen to be right in the track of the current which strikes the south and west coasts of Australia, and should form ideal out-stations for gauging the general condition of this wind system.

That the prevailing winds on the west coast of Australia come from a southerly direction is indicated in the following table, which gives the number of times the wind has blown from each point of the compass at the Perth Observatory during the year 1902, the readings being taken eight times a day

Another table shows that the resultant direction of the wind, at the same observatory for the same year, was south for the months January to April and October to December inclusive.

There seems every reason, then, to hope that the utilisation of information from one of these islands for several months in the year would in time amply repay the initial cost and maintenance of the station.

It is not without interest to remark that the air current which passes the west coast of Australia in July (that is, in winter in Australia) becomes later the south-east trade wind of the Indian Ocean, and eventually reaches the Indian area in the form of the south-west monsoon in the summer months of the northern hemisphere. In the months about July, Western Australia is thus apparently closely connected, meteorologically speaking, with India,

but in the months about January the connection is between Australia and South Africa.

The natural deduction to be made from the above is that the meteorological services of all these countries should be closely in touch with each other. Their combined efforts will certainly considerably increase our knowledge of the meteorology of this vast region, and each will benefit by this mutual interchange of information.

Although mention has only been made of one or two instances in which the employment of islands as meteorological stations would most probably be rewarded with practical results, there are other countries that might equally profit by adopting the same principle.

It is, however, important for the study of world meteorology that many islands should be employed as observing stations. They may not be very ideal places for observers to live in, but a change every few months, and the adoption of self-recording instruments, would possibly simplify matters. Where cables are lacking, and the island in question is of great meteorological importance to son e continent, wireless telegraphy might be employed with advantage. WILLIAM J. S. LOCKYER.

AN OPTICAL CONGRESS AND EXHIBITION. THE aims of the optical convention, which was opened at

the Northampton Institute, Clerkenwell, on Tuesday, May 30, are to increase the interest taken in optical science in this country, to promote an improvement in technical education in optical matters, and to aid the development of the British optical industry. In his address, the chief part of which is subjoined, the president, Dr. R. T. Glazebrook, F.R.S., after explaining the origin of the proposal to hold a convention, and the steps taken to realise it, gives an outline of the history of optical progress during the past two hundred and fifty years with the view of illustrating the close union which has existed between theory and practice at times of marked progress, and of showing how each has reacted on the other in assisting this progress. The programme of the convention includes meetings for papers and discussions, which will be subsequently published in a volume, and an exhibition of optical and scientific instruments of British manufacture, with a catalogue which is intended to serve as a work of reference illustrating the productions of opticians in this country. A description of some of the exhibits follows the president's address abridged below; and an article on the nature and matter of the papers and discussions will appear in these pages after the close of the convention.

PROGRESS OF OPTICAL SCIENCE AND MANUFACTURES.' The study of optics is a fascinating one, and its history full of interest. I do not propose to-night to attempt to cover the whole ground, but to ask you to look at one or two special periods during which, it seems to me, theory and practice reacted on each other in a marked manner, and to consider what lessons we may draw as to the relation which should in these days of ours subsist between the two.

For this purpose I might go back to very early days. Ptolemy in his attempt to discover the laws of refraction -and wonderfully good the attempt was, as we know now -Archimedes with his burning glass, if, indeed, he ever made it, had both practical aims in view. But we will start to-night nearer our own time. The end of the seventeenth century is such a period. The telescope was invented about 1608, the microscope at rather an earlier date, about 1590, both, probably, in Holland.

Galileo, hearing of this, made his first telescope in 1610. In 1611 Kepler, in his Dioptrica," described the astronomical telescope with one or more convex lenses as the eye-piece; with this exception, up to Descartes's book on Dioptrics" in 1637, no other form of telescope but Galileo's was known. The law of refraction was first enunciated by Snell in 1621.

Thus by the year 1660 the importance of the telescope to the astronomer was fully appreciated, and its limitations were being realised. In 1663 Gregory published an account 1 From the inaugural address delivered before the Optical Convention on May 30 by the president, Dr. R. T. Glazebrook, F.R.S.