Imagens das páginas
PDF
ePub

Technology, Boston, Mass., before December 31, 1906. The prize will be awarded at the annual meeting in April, 1907.

Ar the meeting of the Pathological Society of London on May 16, Mr. C. Walker gave a demonstration which seems to solve the nature of the so-called " cancer bodies " (Ruffer's bodies) of malignant tumours, which have been believed by many to be parasitic protozoa. He showed specimens of the normal reproductive cells of the testis containing bodies which are apparently identical with the cancer bodies," but are really the archoplastic vesicles of those cells.

IN the Bulletin of the Johns Hopkins Hospital for April (xvi., No. 169) the most interesting and important communication is by Dr. Clowes on the immunisation of mice against cancer. In certain mice which had been inoculated with mouse cancer, the disease underwent an unexpected and spontaneous retrogression, and it was found that the serum of these animals produced a marked curative effect on the cancerous tumours in other mice suffering from the disease.

DR. W. B. WHERRY records some interesting observations on the biology of the cholera spirillum (Bull. Bureau of Gov. Laboratories, Manila, No. 19), in which he shows that the slight variations in cultural and other characters so often met with in different strains of this microorganism are largely due to slight differences in the culture media employed, particularly in their reaction, and suggestions are given for the more accurate preparation of standard media.

THE Journal of the Royal Sanitary Institute (xxvi., No. 4) contains a report of a discussion on the aërial dissemination of small-pox round small-pox hospitals, in the course of which Dr. H. E. Armstrong, Dr. T. M. Clayton, and others adduce a good deal of evidence against the commonly accepted view of the danger of aërial infection in the neighbourhood of such hospitals. Municipal milk depôts and milk sterilisation is the subject of another paper by Dr. G. F. McCleary.

DR. CHARLES CREIGHTON, who recently paid a special visit to India for the purpose of inquiring on the spot into some of the circumstances connected with the prevalence of plague, read a paper on this disease before the Society of Arts on May 18. Dr. Creighton first criticised the composition of the British Plague Commission of 1898, complaining that there was no epidemiologist upon it. He next gave a somewhat detailed account of the geographical distribution of plague, and directed attention to the difference of incidence of the disease in the villages of the district of Ratnagiri and those of the adjoining district of Satara. In the former all the buildings, roadways, &c., are of stone, and plague occurs little or not at all; in the latter the villages are plague-stricken, and the crowded dwellings are of mud, the floors, &c., being saturated with offal. Dr. Creighton believes that crowded sites too long inhabited and without drainage are the cause of the trouble, which is explicable on the laws of soilinfection enunciated by Pettenkofer and his school.

A PRICED catalogue of pinned specimens of Lepidoptera, issued by Mr. H. Fruhstorfer, of Turmstrasse, Berlin, from whom we have received a copy, should prove useful to collectors.

AMONG Our weekly budget are included three papers on North American zoology. In the first, from the Bulletin of the Brockly Institute (vol. i., No. 5), published by the

Macmillan Company, Dr. J. A. Allan gives a list of mammals from Beaver county, Utah, several of which are described as new. The mammals of this elevated region are stated to differ considerably from their representatives in the adjacent foot-hills. In No. 6 of the same serial Mr. C. Schæfer describes new American beetles, and in the third paper (from the Proceedings of the U.S. Museum) Mr. W. D. Kearfoot diagnoses new tortricine moths from Carolina.

IN the April issue (vol. i., part iv.) of the Records of the Albany Museum Dr. R. Broom discusses the proper signification of the Owenian term "Anomodontia," and comes to the conclusion that it is applicable only to the dicynodonts. He also describes certain new fossil reptiles from Aliwal North, and contributes some important notes on the localities of type specimens of other South African reptiles, especially those in the British Museum. In the course of these remarks, it is pointed out that Anthodon is of Wealden age, and probably, therefore, a dinosaur instead of a pariasaurian, and that the limb-bones described by Owen as Platypodosaurus are almost certainly referable to Udenodon.

I

IN the issue of Biologisches Centralblatt of May 1 the Rev. Father Wasmann brings to a close his important series of articles as to the origin of slavery among ants, and formulates the conclusions at which he has arrived, which are too long to be recapitulated in our columns at length. It may be mentioned, however, that, in the author's opinion, this system of slavery had independent origins at different dates respectively in the formicine and the myrmecine sections of the ant family, and that it has also been independently acquired in different genera and species of these two subfamilies at different times. In general, it seems to have been of later origin in the Formicinæ than in the Myrmecinæ. Moreover, the phenomenon affords confirmation of the biological doctrine that the ontogeny of a group constitutes a brief recapitulation of its phylogeny. In another article in the same issue Dr. O. Zacharias emphasises the importance of modern methods of studying "hydrobiology" in relation to fishculture and fisheries.

PART iii. of vol. xlvii. of the quarterly issue of Smithsonian Miscellaneous Contributions contains an article by Mr. C. D. Sherborn on the species of birds described as new in Vroeg's catalogue, published in 1764. P. S. Pallas is believed to be the real author of the names. The only copy of this work that has come under the author's notice is in the library of the Linnean Society, where it might have been left in well merited obscurity. Social spiders (Stegodyphus sarasinorum) form the subject of another article, by Mr. N. S. Jambunathan, in the same serial. The spiders of this species, which was discovered by the author at Saidapet, Madras, in 1898, live in a sponge-like nest formed of branching net-work with communicating canals and a number of external openings. These nests, which may be attached either to the tips of branches of trees or to leaves of the prickly pear, are ashy-grey in colour, and constructed of leaves and refuse from the spiders' food. Externally is a coat of stout sticky threads of the same colour as the spiders themselves, and sheet-like webs spread in all directions from the nests. Five or six nests are often found together, each of which may be the home of from 40 to 100 spiders, usually in the proportion of seven males to one female. A number of spiders will cooperate to overpower a single large insect.

DURING the last few days paragraphs have appeared in the newspapers stating that a plague of flies has invaded Cardiff Docks, causing much inconvenience. The flies are said to have made their appearance with a southerly wind on Sunday, May 14. Mr. Ernest E. Austen, of the British Museum (Natural History), informs us that specimens forwarded to the museum show that the trouble has been caused by the fly known as Dilophus febrilis, Linn., a very common British species of the family Bibionidæ, met with from April to September, but especially abundant in May. In colour the flies are black, with a shining thorax, and measure about 5 millimetres, or rather less than a quarter of an inch, in length. As in all Bibionidæ, the males are distinguished from the females by the large size of the head, which in the former sex appears from above to be entirely composed of the eyes. Of five specimens sent to the British Museum, all were males. Dilophus febrilis breeds in horse and cattle droppings, in which the larve-white footless grubs measuring half an inch in length, with a dark brown head capsule at the anterior extremity are found in small masses. This fly is quite incapable of biting, as are also all the other species of the same family, so far as at present known, though the possession of an elongated proboscis by two Mexican representatives of the genus Plecia suggests that there may be forms that suck blood. The occasional occurrence of Bibionidæ and other Diptera in immense numbers is well known, and notes on the subject have already appeared in these columns (cf. NATURE, vol. xlviii., 1893, pp. 103, 127, 170). With regard to Dilophus febrilis, Mr. J. W. Douglas, writing in the Entomologist's Monthly Magazine for 1880 (p. 142), describes a swarm of this species at sea off the Norfolk coast on September 2 of that year. It is stated that the air was obscured by the flies as by a cloud, and that a schooner sailing at about a cable's length from the shore was so covered with them that for five hours persons were unable to remain on deck; the air cleared at about 4 p.m. The cause of these phenomenal swarms is still uncertain, but it is probably to be found in exceptionally favourable climatic conditions, which, by accelerating the growth of the larvæ and shortening the pupal stage, cause myriads of flies to appear at practically the same time.

Is the Biological Bulletin (February) Mr. R. S. Lillie discusses the conditions determining the disposition of the chromatic filaments and chromosomes in mitosis, and advances a physicochemical theory, based upon mutual repulsions of the particles of a colloid solution, to explain the sequence of the stages in nuclear division.

A REVISION by Mr. B. Hayata of the Euphorbiacea and Buxacea of Japan, as represented in the herbarium of the University of Tokio, forms article iii. in vol. xx. of the Journal of the College of Science in that university. The number of genera is limited to twenty-four under Euphorbiacea and two under Buxaceæ, and seven new species are recorded. The author has provided figures of the flowers for most of the species.

A BRIEF survey of the progress of the Nilambur Teak Plantations, Madras, from its inception by Mr. Conolly in 1840 to its present condition, when the receipts more than balance the cost, is contributed by Mr. R. McIntosh to the Indian Forester (March). The harvest time is still thirty-five years ahead, when the fellings are expected to produce a revenue of 40,000l. a year. The difficulty experienced at first in getting the seed to germinate was overcome by soaking the seeds before planting, and by

The

keeping the soil thoroughly moist after planting. teak forests of Burma form the subject of another article, in which Mr. R. S. Troup comes to the conclusion that useful as fire protection may be in most forests, annual burning in moist mixed forests of teak and bamboos is decidedly efficacious.

THE appearance of a Nature-study Review, edited and published by Mr. M. A. Bigelow in Lancaster, Pennsylvania, indicates that the subject is making progress in the United States. A discussion in the first number as to the scope of nature-study has led to a general expression of opinion that it differs from natural science in so far as it lacks the characteristic organisation of science, and that it should be confined to elementary schools; further articles on the subject appear in the March number, which is the second of a bi-monthly issue. Amongst the articles giving the experiences of teachers one by Dr. E. A. Bigelow directs attention to the convenience of putting up the salts required for plant food solutions in tabloid form.

IN Spelunca (Bull. de la Soc. de Spéléologie, tome v., Nos. 39 and 40) there are interesting articles on the caverns and subterranean water-courses of the Mendip Hills, by Mr. H. E. Balch, and on those of the Jura Mountains by M. E. Fournier.

MR. E. C. DAVEY, who in 1874 contributed to the Transactions of the Newbury District Field Club an essay on the sponge-gravel beds near Faringdon, with photographs of some of the fossil sponges, has revised and amplified his article under the title "The Neocomian Sponges, Bryozoa, Foraminifera, and other Fossils of the Sponge-gravel Beds at Little Coxwell, near Faringdon." This is now published by Messrs. Dulau and Co., price 5s. net, and it contains five photographic plates of sponges, Echini, and Foraminifera. The nomenclature of the sponges is revised in accordance with the researches of Dr. G. J. Hinde, but the author does not wholly agree with the determinations made by that palæontologist, and adds other species, one new species being figured and briefly described. Under the heading "Bivalves," the author includes brachiopods and lamellibranchs; he makes no reference to the occurrence of Belemnites, to which Mr. G. W. Lamplugh directed special attention in 1903 (Geol. Mag., p. 32).

BASING his conclusions largely on the capacity of the cranium, but also taking into account other characters, Mr. A. da Costa Ferreira has attempted to dissect out, as it were, the probable racial constituents of the Portuguese, and has set forth his results in the Bulletin de la Société d'Anthropologie de Paris (5e. sér., tome v., p. 473). He finds a short, mesorhine dolichocephalic type with a small head which he thinks belongs to the Cro-Magnon race, and a tall, leptorhine dolichocephalic type with a large head. The mesaticephals are partly attributed to a brachycephalic mixture; those of short stature, leptorhine, and with a large head, are thought to belong to the race of Grenelle or to a Celtic invasion. The small headed, leptorhine mesaticephals are probably of Semitic origin, while the mesorhines may be of Berber extraction.

In order to make more widely known and more easily accessible to American students the results of important researches on the Maya hieroglyphs, printed in the German language, the Peabody Museum Committee on Central American Research has begun a series of translations of which the first, on the representation of deities of the Maya manuscripts, by Dr. P. Schellhas, has been published as vol. iv., No. 1, of the Papers of the Peabody

Museum, Harvard University. In this valuable enumeration Dr. Schellhas is very careful not to theorise or to go beyond the warrant of the manuscripts themselves. In several cases he refers to diverse views concerning the names of the gods in question; but, as he truly observes, "these different opinions show on what uncertain grounds such attempts at interpretation stand, and that it is best to be satisfied with designating the deities by letters and collecting material for their purely descriptive designation. In vol. iii. of the same Papers are illustrated accounts of the Cahokia and surrounding mound groups, by Mr. D. I. Bushnell, and of the exploration of mounds in Coahoma, co. Mississippi, by C. Peabody. In vol. i. Mrs. Zelia Nuttall gives a very interesting account of a penitential rite of the ancient Mexicans mainly derived from Spanish sources. Blood was drawn from cuts in various parts of the body, including the tongue and ears; the rite of voluntarily drawing blood, principally from the ear, was a feature of every-day life in ancient Mexico, and was performed by young and old. It constituted an act of humility, thanksgiving, penitence, or propitiation.

THE Survey Department of Egypt has published an important paper on the rainfall of the Nile basin in 1904, by Captain H. G. Lyons, director-general of the service. Five years ago there were only six or eight places where the rainfall was being measured regularly; now, thanks chiefly to the efforts of Captain Lyons, there are more than forty, of which thirty-two lie to the south of Berber (lat. 18° N.). He points out that to understand the seasonal variation of the rainfall the relative positions of the equatorial low-pressure belt, and the high-pressure areas to the north and south of it at different seasons, must be taken into consideration. In the low-pressure area there is an ascensional movement of the air, so that its moisture is condensed to form clouds and rain. This ascensional movement depends upon the heating effect of the sun, and it is shown month by month how the lowpressure area varies with respect to the sun's position from south to north, and back to south again. The carefully prepared tables and diagrams show, as a general result, that the rainfall of 1904 in the Nile basin was below the average; in the equatorial regions it was somewhat deficient in the earlier part of the year, and above the average in the autumn.

A SOMEWHAT striking paper has been published by Prof. Ronald Ross, F.R.S., of Liverpool University, on verb functions, with notes on the solution of equations by operative division (Proceedings of the Royal Irish Academy, xxv., A, 3). The writer points out that whereas symbols such as f and are used to denote functions in general, no notation exists which can explicitly represent the operation of forming any particular function of any argument, apart from the argument itself, except in certain simple cases as exemplified by the prefixes log, sin, &c. The notation proposed by Prof. Ross meets this want. It depends on the use of a purely symbolical letter B to denote the base of a given operation, this symbol occurring in the verb function or operator. When this verb function operates on a subject x, it produces the result obtained by writing x for B in the operator. For example, [Bm/"](ab)=(ab)m/", [Blog B-1]x=x log x-1, [ cos B]x cos x, and so on. Another peculiarity is the use of square brackets to enclose each separate operation, the necessity of which may be illustrated by the following example :[(a+B)2]x_represents (a+x)2, whereas

[ocr errors]

[a+B]2x=[a+B][a + B]x=(a+b] a+x)=a+ (a + x)=2a+x.

[merged small][merged small][merged small][merged small][merged small][merged small][merged small][merged small][ocr errors][merged small]

notes

REFERENCE has already been made in these (NATURE, vol. 1xx. p. 583) to the simple form of telescope pyrometer invented by M. Féry for measuring high temperatures. This instrument is now being sold by the Cambridge Scientific Instrument Co., Ltd., who have been appointed sole agents for its sale in the United Kingdom, the British colonies, and in the United States; it is made in two forms, a mirror pyrometer, recording temperatures between 500° C. and 1100° C., and a lens pyrometer, reading between 900° C. and 3500° C.

Prof. Moissan has published, in the form of a pamphlet having the title "La Chimie minérale, ses Relations avec les autres Sciences," an address delivered last September at the Congress of Arts and Sciences at St. Louis. Prof. Moissan, who by his own researches and those of his colleagues has so widely enlarged the domains of inorganic chemistry, whilst regretting that this branch of science is still systematically imperfect as compared with organic chemistry, emphasises the fact that during the past few years its study has again resumed a place of honour. This has been due largely to the discovery of the gases of the atmosphere, to research at high and low temperatures, the investigation of the rare earths, and to the increasing tendency to the fusion of chemical and physical methods. "Many important investigations still remain to be made in inorganic chemistry, but for success very refined methods and a high degree of accuracy will be required. Chemical research must acquire the precision of physics." Finally, it must be recognised that experiment is the sole guide to truth, and that Faraday's saying still holds true that chemistry is essentially an experimental science. THE recent researches of M. Berthelot on meability of fused quartz vessels to gases at high temperatures have led him to study glass from the same point of view, with very interesting results. In many analytical processes, and more especially in the analysis of organic compounds, it is tacitly assumed that at temperatures below its melting point glass is impermeable to oxygen, nitrogen, and carbon monoxide and dioxide. In the current number of the Comptes rendus, M. Berthelot gives an account of some experiments on glass, the mode of working being the same as that used for the quartz tubes (see NATURE, April 13, p. 568) with the exception that the tubes were necessarily slowly cooled, and finds that at temperatures between 550° C. and 800° C. glass tubes are permeable to gases. He compares the passage of gases through slightly softened glass to the gaseous exchanges taking place at the ordinary temperature through the walls of indiarubber tubing, and emphasises the importance of this property of glass, hitherto unsuspected, in many chemical and physical investigations at high temperatures.

the per

MESSRS. CROSBY LOCKWOOD AND SON will publish shortly a work on " Modern Lightning Conductors," by Mr. Killingworth Hedges, honorary secretary of the Lightning Research Committee.

As appendix to Mr. R. L. Taylor's "Student's Chemistry" has been published by Mr. John Heywood. It a nsists of two sections; the first part deals with the radio-active elements, and the second is an introduction to the study of organic chemistry.

We have received from the Art. Institut Orell Füssli, of Zurich, Nos. 177, 178, and 179 of their "Illustrated Europe" series of handbooks. The three parts are bound together in a convenient little volume with the title "Grisons Oberland." The guide book is by Dr. Chr. Tarnuzzer, and a historical sketch has been contributed bs Prof. J. C. Muoth. The translation into English was done by Dr. and Mrs. Spöndly-Blakiston. Visitors to this interesting part of Switzerland will find interesting scientific, historical, and topographical information in this guide book. The book may be obtained in this country from Messrs. Hachette and Co.

MESSES. OLIVER AND BOYD have published the ninth volume of the "Reports from the Laboratory of the Royal College of Physicians, Edinburgh." The volume is edited by Sir J. B. Tuke and Dr. Noël Paton. The papers included fall under two categories; the first comprises fourteen papers describing researches on the ductless glands under the Mason fund, and the second consists of general researches in physiology, pathology, and pharmacology.

WE have received from Mr. John Grant, of Edinburgh, a caralogue of scientific books, chiefly on botany, zoology, and geology, and a catalogue of recent purchases—including some well known works of science-all of which are offered at greatly reduced prices.

MR. W. BUTLER, Southport, has devised a new type of camera stand-called the Swingcam-to facilitate the photography of natural history subjects. The stand enables a photographer to point the lens of a camera at any angle and fix it in that position, without the use of a swinging back or front or any other independent attachThe Swingcam tripod head can be fixed in a horizontal or vertical position, or at any angle, and is also capable of being inverted if desired. Naturalists and others who occasionally have to use cameras in awkward positions will no doubt find these devices a convenience.

ment

[merged small][ocr errors]

We have received from Messrs. Henry Sotheran and Co., 140 Strand, W.C., a copy of their latest catalogue of second-hand books, including numerous scientific works; and from Messrs. John Wheldon and Co., 30 Great Queen Street, W.C., a catalogue of a miscellaneous collection of Looks, comprising many dealing with biology, geology, and mathematics.

MESSES DAWBARN AND WARD, LTD., have published a second revised edition of " Photographic Failures: Preventica and Cure," by Scrutator" of the Photogram.

OUR ASTRONOMICAL COLUMN. NEWLY DISCOVERED NEBULE.-In No. 4013 of the Astronomische Nachrichten Prof. Max Wolf announces the discovery of a small, but beautiful, nebula the position of which, referred to the equator of 1900-0, is as follows:a=13h. 58m. 33·448., 8=-9° 39′ 36′′. This object was discovered on a plate exposed during a search for minor planet (126), Velleda, and is of a spiral form, of the unusual S-shaped variety, the nucleus being of the fourteenth magnitude. Its diameter in R.A. is about o'·75, and in dec. about 1'0.

A second nebula of especial interest was found in the position (1900-0) R.A. = 13h. 58m. 15.175., 8=-9° 40' 10". This object is 1' in length along its major axis, which has a position angle of about 120°, and is of the Andromeda nebula form.

THE BRUCE TELESCOPE REFERENCE PHOTOGRAPHS.-When the 24-inch Bruce telescope of the Harvard College Observatory was being planned it was expected that the instrument might be useful in assisting in the discoveries of new satellites, and this expectation was realised in the discovery of Phoebe. A number of plates of each planet have been taken since 1893, and of these Prof. Pickering now gives the details as to object photographed, exposure, date and region, in Circular No. 97 of the Harvard College Observatory, hoping that the knowledge of their existence may assist other observers of possible satellites. The list includes 12 plates exposed for Mercury, 2 for Mars, 6 for Vesta, 21 for Jupiter, 12 for Uranus, and 3 for Neptune. The Saturn plates were fully described when the manner of the discovery of Phoebe was related in a former publication. The limiting magnitude of the objects shown on these plates may be taken as 17.0 or 175, and therefore the photographs may prove useful in the correction of the elements of Jupiter's newly discovered satellites when more is known of the positions of these two objects.

СОМЕТ 1904 II. (1904 d).-A continuation of the ephemeris for comet 1904 d is given in No. 4012 of the Astronomische Nachrichten by Herr M. Ebell.

This comet is now only about one-sixth as bright as when discovered, and is gradually becoming fainter. Its position on May 26, according to the ephemeris, will be a (true)=2h. 23m. 48s., ☎ (true)=+64° 50', which is about 2 south of Cassiopeia, and the object is travelling slowly towards the constellation Camelus with a very slightly increasing declination.

TWELVE STARS WITH VARIABLE RADIAL VELOCITIES.Further results of the spectrographic work performed by the D. O. Mills expedition from Lick Observatory to the southern hemisphere are published in Bulletin No. 75 of that observatory.

Twelve stars have been found by Prof. Wright and Dr. Palmer to be spectroscopic binaries, some of them, mentioned below, having features of especial interest. a Phoenicis has a period of about 190 days. The system of Eridani has been found to be very similar to that of Mizar, the brightest component, @,, having a composite spectrum similar to that of the star named. a Puppis, a Volantis, a Carinæ, and and p Velorum are amongst the other stars of which the radial velocities have been found to be variable.

DOUBLE "CANALS" ON MARS IN 1903.-In Bulletin No. 15 of the Lowell Observatory Mr. Lowell gives, and discusses in detail, the results of his observations of the Martian* canals during 1903. Before proceeding to the account of the actual observations, he comments on the various theories which have been advanced in argument against the reality of the “ doubling" phenomenon. The " diplopic or out-of-focus theory is refuted for five reasons, the chief of which is that for any special epoch the width of each individual double canal remains con

[merged small][merged small][ocr errors]

the chief argument against it being that the ambiguity of real and false effects only exists at the limit of vision, whereas most of the canals considered are, when well seen, far within this limit.

A number of interesting points concerning the canal systems are deduced from the 1903 observations, but only one or two of the more striking may be mentioned here. (1) The majority of the double canals do not exceed 3°.2 (degrees on the planet's surface) in width; (2) at the time of maximum visibility the two members of each double are generally of equal strength, but as they wane one of them usually becomes apparently stronger than the other; (3) the double canals appear to congregate in special longitudes and latitudes, in the latter case especially favouring the equatorial regions, a fact which Mr. Lowell urges as an argument against the diplopic theory; (4) the double canals are peculiar to the lighter regions of the planet's surface, although single canals are, apparently, just as numerous in the darker as in the lighter regions; the double canals, however, are always connected, directly, or through the medium of similar objects, with the darker

areas.

66

[ocr errors]

CATALOGUE OF NEW DOUBLE STARS.-Prof. Hussey's ninth catalogue of double stars, discovered with the 12-inch and 36-inch refractors of the Lick Observatory, and mostly measured with the latter instrument, is contained in Bulletin No. 74 of that observatory. The preceding catalogues have severally appeared in Nos. 480, 485, and 494 of the Astronomical Journal, and Nos. 12, 21, 27, 57, and 65 of the Lick Observatory Bulletins.

The present publication gives the catalogue and D.M. numbers, the position and the distance and position-angle determined at each observation for each of the double stars recorded. The catalogue numbers extend from 801 to 1000 inclusive, and run consecutively.

THE ROYAL SOCIETY CONVERSAZIONE.

MANY instruments and devices of scientific interest were shown at the Royal Society's conversazione on Wednesday, May 17. As usual, the exhibits illustrated methods and results of recent work in various branches of science, and the subjoined summary of the official catalogue contains a few particulars relating to them.

In the course of the evening lantern demonstrations were given in the meeting-room by Dr. E. A. Wilson, Sir Oliver Lodge, and Mr. Perceval Landon. Sir Oliver Lodge demonstrated the use of electric valves for the production of high-tension continuous current. Electric vacuum valves, which it is now found were suggested in a letter by Sir George Stokes twenty years ago, have as their function the entrapping of a portion of electricity by permitting its passage in one direction and stopping its return. They therefore can be employed to accumulate electricity supplied from an intermittent or jerky source and to store it at a steady high potential; so that it may thereafter maintain a current through a very high resistance, as in electrostatics, and may produce X-rays, or pointdischarge, or other continuous high-tension effects, and enable a small portable coil to imitate some of the effects of a much larger one by storage and accumulation of impulses. Among the applications contemplated are the separation of metallic fume and the dissipation of fog. Dr. Edward A. Wilson showed a number of Antarctic views illustrating the life and work done on board the Discovery during the years 1902 to 1904, and views of the seals, penguins, and other birds met with in the Antarctic circle; and Mr. Perceval Landon exhibited pictures of the road to Lhasa.

The other exhibits are here grouped together according to subjects more or less closely related to one another. Specimens illustrating the action of light and of radium upon glass: Sir William Crookes, F.R.S. (1) It is well known that many samples of colourless glass containing manganese slowly assume a violet tint when exposed to sunlight. In some specimens of glass exhibited the pieces were of all depths of tint, from deep violet, almost black in thick pieces, to pale amethyst. Analysis shows the glass to contain manganese. Heating the glass in a covered crucible to its softening point discharges the colour,

leaving the glass white and transparent. The coloration is not superficial. On immersing a piece of the coloured glass in a liquid of about the same refractive index as itself, the colour is seen to have penetrated throughout the mass. Radium, acting for a few days, even through quartz, will produce as intense a coloration in a piece of this glass as exposure to the sun on the Pampa has taken years to effect. Six pieces of glass from the greenhouses at Kew Gardens illustrated changes which took probably about fifty years to complete in our climate. Purple spots were produced on two of these specimens by Sir William Crookes by the action of 15 milligrams of radium bromide in a quartz tube in the course of ten days, the beginning of change being well marked at the end of two days. In a specimen of manganese glass exposed to light for forty years as a pane of a greenhouse, the ends of the glass which had been protected from light by the window frame were colourless. In the expectation that radium might have a reducing effect on the manganese compound, Mr. F. Soddy submitted a portion of the pane to the action of 30 milligrams of radium bromide for three days in May, 1904. The colour, however, instead of being diminished, was intensified. Specimens were also shown illustrating the coloration of glass, quartz, and fluorspar by the B rays of radium.

Action of actinjum or emanium emanation on a sensitive screen: Sir William Ramsay, K.C.B., F.R.S. Actinium or emanium are different names, adopted by Debierne and Giesel respectively, for the same substance, separable from pitchblende, and accompanying lanthanum. It gives off an emanation, of which the period of activity is very short-a few seconds. When this emanation impinges on a sensitive zinc sulphide screen, the screen becomes luminous. The luminous patch can be blown away, and in a second or two reappears.-Phosphorescence caused by the B rays of radium: Mr. G. T. Beilby. Phosphorescence of calcspar and other substances (1) during exposure to the rays; (2) after removal from the rays; and (3) revived by heat after secondary phosphorescence has died down. The storage of phosphorescence and the coloration effects are due to partial electrolysis of the calcium carbonate or other substance by the stream of negative electrons. A proportion of the ions re-combine at once, others continue to re-combine after the rays have ceased to act, and the remainder only re-combine when the mobility of the crystal molecules is increased by heat.-Skiagrams of the hands of Machnow, the Russian giant, and of O'Brien, the Irish giant: Mr. S. G. Shattock.

Large echelon spectroscope: Prof. A. Schuster, F.R.S. This echelon spectroscope, constructed by Messrs. Adam Hilger, Ltd., consists of 33 plates, and has a resolving power equal to that of an ordinary grating of 329,000 lines in the first order.-A hand refractometer: Mr. G. F. Herbert Smith. By means of this form of refractometer the refractive indices of any translucent substance, the refractive power of which lies within the effective range of the instrument, 1400 to 1.760 approximately, may be determined with ease and celerity, to units in the second place of decimals if ordinary light, and to two or three units in the third place of decimals if the monochromatic light emitted by a volatilising sodium salt be the source of illumination.-The Ashe-Finlayson comparascope: Mr. D. Finlayson. This accessory to the microscope has been designed to enable the images of two different objects, separately mounted, to be projected side by side into the field of view, thereby enabling a thorough comparison to be made of their respective points of difference and resemblance. The apparatus consists of a prism placed above the primary objective which reflects to the ocular the rays from a secondary objective placed at right angles to the optic axis of the microscope.-(1) Torsion balance, used in radiation pressure measurements, by Nichols and Hull; (2) vacuum tube, of Nichols and Hull, to illustrate the repulsion of comet tails by the sun: Prof. E. F. Nichols. An optical appliance to facilitate visual perception of ultra-microscopic particles: Mr. Carl Zeiss. The apparatus consists of a projection table provided with an arc lamp, optical bench, two projection aplanats, and a precision slit. (The use of sunlight instead of the are lamp is preferable.) Particles of far less than half a wave-length can be made visible with this apparatus.

« AnteriorContinuar »