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E. N. Browne, in the August number of the Journal of Experimental Zoology (vol. vii., No. 1), dealing with the production of new hydranths by the insertion of small grafts from another individual of the same species. This paper is particularly interesting on account of the ingenuity of the methods employed. In order to determine the exact origin of the regenerating material, the author makes use of Whitney's discovery that the green colour can be entirely removed from Hydra viridis, without killing the animal, by keeping it for some weeks in a 0.5 per cent. solution of glycerin. The artificial white hydras thus produced form perfect grafts with ordinary green forms, giving rise to parti-coloured colonies in which the boundaries between the tissues of the green and white components remain clearly defined.

Irish Gardening (October) contains various seasonable articles, notably on the cultivation of seakale and the gloxinia. A very charming bell-shaped ericaceous plant, Zenobia speciosa, is recommended for the garden by Mr. C. F. Ball; in the variety pulverulenta it attains to the dimensions of a good-sized bush. It requires a peaty soil or the nearest equivalent, and is propagated from seed or by layers.

THE Country Home (October) appears in an enlarged form from the offices of the Sphere and Tatler. The botanical and zoological articles are chiefly utilitarian or popular. The intensive cultivation of asparagus is explained by Mr. L. Terasse, and vegetative propagation forms the subject of an article by Mr. W. M. Webb, while Mr. H. B. Buchanan gives advice on the breeding of pigs. FOLLOWING up a line of work instituted in the United States of America, the examination of parasitic fungi that attack scale insects has been taken up by the Department of Agriculture for the West Indies. Three species of Ascomycetes, Sphaerostilbe coccophila, Ophionectria coccicola, and Myriangium Duriaei are specified in the Agricultural News (September 18) as having been taken on scale insects infesting lime or citrus trees in Dominica, St. Lucia, and other islands, and a fourth fungus is noted, but not identified. It is proposed to experiment with cultures of these fungi on nutrient media which could be distributed to cultivators.

THE most striking point in a description of fungus maladies of the sugar-cane, prepared by Dr. N. A. Cobb, and published in Bulletin No. 6 of the division of pathology and physiology in connection with the Hawaiian Sugar-planters' Association, is the attribution of parasitism to the phalloid fungi Ithyphallus coralloides and Clathrus trilobatus. The mycelium of Ithyphallus was found attached to cane trash and the roots, while the mycelium of Clathrus passed in among the roots of canes where disease was abundant, so that the author classes them with species of Marasmius as sources of root disease. With the view of identifying the mycelium of these Phalloidea, a special study was made of their sphæro-crystals.

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IN. connection with visit of German systematic botanists, Dr. E. Issler prepared an account of vegeta

tion conditions in the Central Vosges Mountains, which is published in Engler's Botanische Jahrbücher (vol. xliii., part iii.). The formations distinguished in the montane region are spruce, beech, mixed fir woods, and the vegetation of the forest streams. It is a curious fact that the beech in many places ascends higher than the conifers, the reason being that the upper tree limit, at the low altitude of 4000 feet, is determined by the wind, which the beech is better able to withstand. In the subalpine region

different types of flora are provided by the rocks, meadows, and swamp, and in certain parts there are areas of ling and sphagnum moors. Among the rare plants to be found are Mulgedium alpinum, Rhodiola rosea, Luzula spadices, two species of Isoetes, and Subularia aquatica.

THE Bio-chemical Journal for September (iv., No. 8) contains a paper, by Dr. Otto Rosenheim, on the nomenclature of lipoid substances. He proposes to classify them in three main groups, the cholesterins, the cerebrogalactosides, and the phosphatides. Prof. Moore and Drs. Wilson and Hutchinson contribute a paper on the biochemistry of hæmolysis.

PROF. HALLIBURTON, in the Journal of Hygiene (vol. ix., No. 2, September), directs attention to the fact that large quantities of flour, both in this country and abroad, are artificially bleached. Some experiments he has performed distinctly indicate that both the starch and the gluten are rendered less digestible by the process of bleaching, though whether the change is sufficient to be serious to children or invalids is a question on which there is at present no evidence.

IN the Bulletin of the Johns Hopkins Hospital for September (xx., No. 222), Dr. Charles White discusses in a suggestive manner the municipal management of tuberculosis. He points out that our struggle must be for an immune race, not for the extermination of the last tubercle bacillus. More and more we see the evidence of protection of small doses in healthy resistant bodies. In municipalities the aim should be to get rid of sources of large doses of tubercle bacilli, and to establish resistant bodies by healthy lives, mainly in the children.

AN account of the mathematical work of Sully Prudhomme is given by Prof. H. Poincaré in the Revue générale des Sciences for August 15. Sully Prudhomme received a scientific education in his youth, but was prevented by ill-health from attending the École polytechnique. That he nevertheless gave a large amount of attention to mathematics is evidenced by the numerous manuscripts left by him, including the rough drafts of a memoir on geometry. It appears, however, that the manuscripts now in existence cannot be regarded as more than rough drafts of ideas which Prudhomme had further developed and considerably modified after writing them. Prof. Poincaré concludes that it would be undesirable to publish them in extenso, and he therefore devotes the concluding portion of his paper to a general account of their salient features.

UNDER the title of "The Gambler's Ruin" (Annals of Mathematics, x., 4), Prof. J. L. Coolidge discusses certain problems connected with games of chance which have not hitherto received complete treatment. It is pointed out that while the problem of determining the odds that one player may ruin another has been worked out thoroughly for the case where the amount staked at each turn is the same, the case where the stakes are varied, whether they be limited or unlimited, has been less fully discussed. The author considers the "systems proposed at Monte Carlo and elsewhere, and gives a deductive proof that no such system can have more than an easily calculable chance of success. He concludes with the quotation from Sir Hiram Maxim's book:"Je me rends parfaitement compte du désagréable effet que produit sur la majorité de l'humanité, tout ce qui se rapporte, même au plus faible degré, a des calculs ou raisonnements mathématiques."

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A SYSTEMATIC study of the influence of the surrounding medium on the lines of the spark spectrum has been undertaken by Dr. H. Finger at the suggestion of Prof.

Konen, of Münster, and his principal results are summarised in No. 17 of the Verhandlungen der deutschen physikalischen Gesellschaft. A comparison has been made between the spectra of more than twenty metal electrodes in air and in water, the spark being produced by an induction coil of 40 cm., having a capacity of 0.02 microfarad in parallel with its spark gap. The spectra in air and in water were photographed on the same plate, a concave grating of radius 180 cm. being used. The spectra in water show no air lines, but a large proportion of them show a more or less extended continuous spectrum with the lines of water vapour reversed. Some lines are unchanged, while others are broadened on one or on both sides, lines belonging to the same series being modified in the same sense. No trace of the spectra of salts in solution in the water has in any instance been detected.

PART iii., vol. xvi., of the Proceedings of the Cotteswold Naturalists' Field Club maintains the high standard of style and illustration which distinguishes this publication.

streams, formed in the drainage area before any definite line of principal stream has been settled." Accounts are given of places and objects of scientific interest visited during excursions, and among these is a record of an excursion to Shepton Mallet and Vallis Vale, which is well known for its romantic scenery and geological unconformities. The report contains the accompanying illustration, reproduced by permission of the council of the Geological Society, of the classic section showing Oolite resting upon Carboniferous Limestone, which was pictured by Sir H. de la Beche. Short papers by Messrs. L. Richardson and C. Upton, and a report by the Rev. H. J. Riddelsdell, on the progress made in connection with the flora of Gloucestershire, complete the issue.

Le Radium for August contains a very useful table of the principal minerals containing uranium and thorium, prepared by M. B. Szilard, of Madame Curie's laboratory. It occupies seven pages of the periodical, and gives the name, the composition, the percentages of uranium and of

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View of Quarry, showing the Inferior Oolite resting unconformably upon the Carboniferous Limestone in Vallis Vale. Photograph by Prof. S. H. Reynolds.

A large part is concerned with the record of excursions chiefly to places of geological or antiquarian interest, and is illustrated by no fewer than nine plates of photographic reproductions. Of the papers published, the longest is on "The Lower Severn: Valley, River, and Estuary from the Warwickshire to the Bristol Avon," by Mr. T. S. Ellis. The principal aim of the author is to show that the generally accepted views of river development associated with the name of Prof. W. M. Davis are not applicable to the district with which he deals, and by inference to other districts also. His position is indicated by the following sentence :-" As I believe, we cannot have a right conception of the development of rivers unless we keep our minds free from all idea of original lines of streams or of any principal line as the initial condition. In my view, a river system is evolved not into, but from a network of

thorium, the localities in which the mineral is found, and its crystalline form. In addition, a map of the world, in which the localities are shown, is given.

MR. HAROLD MOORE, of Woolwich Arsenal, read a paper on the Brinell method of determining hardness at the International Association for Testing Materials. We note from an abstract in Engineering for October 8 that the author's results show that the thickness of the test specimen has no influence on the result provided that the depth of the impression made by the ball does not exceed one-seventh the thickness of the specimen. A safe rule to be adopted is that the distance of the centre of the impression from the edge of the specimen should not be less than 2.5 times the diameter of the impression. For calculating the hardness number, 30° should be chosen as the standard angle of impression, this giving a diameter of impression equal

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A REVISED impression of Sir Robert S. Ball's little work "Time and Tide" has just been issued by the Society for Promoting Christian Knowledge.

A CHEAP edition of "Extinct Animals," by Sir E. Ray Lankester, K.C.B., F.R.S., has been published by Messrs. Constable and Co., Ltd. The original edition of the work was reviewed in NATURE of November 2, 1905 (vol. lxxiii., No. 1879).

WE are in receipt of a new catalogue of books and papers (more than 1400 in number) dealing with ornithology which Messrs. John Wheldon and Co., of Great Queen Street, W.C., have for disposal.

THE October classified list of second-hand scientific instruments offered for sale or hire by Mr. Charles Baker, of High Holborn, has reached us. The catalogue, which contains upwards of 1300 items, will be sent free of charge upon request.

MM. A. HERMANN ET FILS, of Paris, have published a translation into French, by Dr. Paul Lemoine, of Prof. James Geikie's "Structural and Field Geology," which was reviewed in these columns on July 6, 1905 (vol. lxxii., p. 223). M. Michel-Lévy has contributed a preface. price of the French work is 15 franes.

The

A NEW edition (the eighth) of "Quantitative Chemical Analysis," by Clowes and Coleman, has been published by Messrs. J. and A. Churchill at 10s. 6d. net. The work has been revised and enlarged, but the size of the page having been increased the thickness of the volume remains as before.

MESSRS. CONSTABLE AND CO., LTD., have sent us a cheap edition of "Time and Clocks," by H. H. Cunynghame, C.B. A review of the first edition appeared in the issue of NATURE for January 17, 1907 (vol. lxxv., No. 1942).

OUR ASTRONOMICAL COLUMN. MARS. The advisability of watching Mars closely, at this period of favourable opposition, and seasonal changes on the planet itself, is illustrated by a brief message communicated to the Astronomische Nachrichten (No. 4362, p. 303, October 9) by M. Jarry Desloges. Whilst the planet, was, being observed at 9h. 15m. on October 6, a projection was seen on the terminator in the neighbourhood of Electris. This projection lasted for ten minutes only, whilst a similar one observed by Messrs. Lowell and Slipher, on May 25, 1903, endured for only thirty-one minutes; the latter was ascribed to a cloud of dust some 300 miles in length.

In No. 4361 of the same journal M. Jonckheere announces the discovery, on September 28, of a canal which is probably a new one, and extends from Cyclopum Lucus to Hephaestus; the same observer records a further observation of the new land "Stella" on October 7.

A large number of observations of different features are

recorded and illustrated by MM. Quénisset and Antoniadi in the October number of the Bulletin de la Société astronomique de France. Numerous canals were observed, the Solis Lacus was seen to be divided, and important changes in the colour and visibility of various regions were closely followed. M. Antoniadi is confirmed in his opinion that these changes are caused by the passage of Martian clouds across the various features, and, from the yellowish tinge which colours the indistinct areas, he confirms the opinion expressed by Prof. W. H. Pickering in 1905, that these Martian clouds are probably yellow.

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SOLAR OBSERVATIONS: A NOVEL SPECTROSCOPE.-In order to continue his solar observations, Mr. W. M. Mitchell found it necessary, at the Haverford College Observatory, to devise a large spectroscope which might be used in conjunction with a small equatorial. The telescope at Haverford is of 10 inches aperture and 12 feet 6 inches focal length, and cannot, therefore, carry a large, and consequently heavy, spectroscope of the ordinary type. Acting upon a suggestion from Prof. Hale, he has erected a spectroscope which is mounted upon, and is parallel to, the telescope tube, and finds that the device very satisfactorily. The beam from the 10-inch objective is reflected on to the slit of the spectroscope by a 90° prism, and, passing through the slit, is again reflected by a similar prism on to a 3-inch collimating lens of 39 inches focal length. Thence it passes to a grating and back through the 3-inch lens to the eye-piece, the grating and lens being slightly tilted. A negative lens placed between the 10-inch objective and the first reflecting prism gives a larger image, which in Mr. Mitchell's observations was of 32 inches diameter. The spectroscope tube is constructed of wood, saturated with hot paraffin before assembling to obviate subsequent warping.

With this instrument Mr. Mitchell gets a resolving power of 70,000 in the third-order spectrum, and was able to observe visually the Zeeman effect in sun-spot lines. An interesting observation on May 11 showed that at one end of a spot "bridge certain lines were doubled, whilst at the other end, the farthest from the centre of the spot group, the same lines were triple; other lines were double in both regions. A list of lines, recorded as bright in a chromospheric outburst on January 21 7h. to 9h. G.M.T., is also given, and Mr. Mitchell urges the necessity for more laboratory work in connection with chromospheric radiations.

We regret to learn that astronomical observations are to be suspended at the Haverford Observatory, and, consequently, Mr. Mitchell's observations cannot be continued. THE AURORA OF SEPTEMBER 25.-In No. 4361 of the Astronomische Nachrichten (p. 287, October 7) Herr Torvald Köhl records that a fine display of the aurora was observed at Odder, Denmark, on September 21, and adds that a similar display was observed in Stockholm on September 25.

SEPTEMBER METEORS.-The appearance of a magnificent fireball on September 27d. 7h. 20m. is recorded by Herr Köhl, who observed it at the Carina Observatory, Odder, in No. 4361 of the Astronomische Nachrichten. Herr Köhl finds from his meteor-catalogue that he observed similar apparitions on September 27-28 in ten different years between 1870 and 1909. He also has records of meteors on December 12-13 for eleven years between 1875 and 1908.

HYDROGEN LAYERS IN THE SOLAR ATMOSPHERE.—In the Comptes rendus for September 20 (No. 12, p. 521) MM. Deslandres and d'Azambuja review the work which has been done in separating the various layers of calcium vapour in the sun's atmosphere, and describe the results of similar researches on the hydrogen and iron vapours recently carried out at Meudon.

The image, obtained by using the centre of the Ha line, differs from the Mount Wilson photographs, and shows the details, exactly, of the K, calcium images, the same dark filaments and the same bright areas. The authors suggest that the Mount Wilson images were produced by mixtures of the different parts of the Ha line, and that the sinuosities in the edges of the various sections might produce this effect. In the dispersion used at Meudos I mm. =6 Å.

PERGY SLADEN MEMORIAL EXPEDITION IN SOUTH-WEST AFRICA, 1908-9.1

II.

IN the latitude of Loanda (8.9° S.), behind a dry, sparsely populated coastal belt about 150 miles wide, lies a mountainous zone, for the most part densely forest-covered

water-channels, dense crops of the erect plumose awns of Aristida seeds, forced beneath the surface by their hygroscopic movements, were commonly seen. So unusual a supply of food had tempted into the vicinity of the town springbok, gemsbok and other antelopes, while ostriches had reappeared after an absence of many years. Very large Welwitschia plants were found in abundance about eight miles to the south of Mossamedes in the direction of Cape Negro, the locality in which it was discovered by Welwitsch. The plants had coned freely, but almost without exception the cones, severely attacked by a fungus (probably a Cladosporium), were in a state of decomposition-no doubt another consequence of the excessive atmospheric humidity earlier in the season. A large number of young seedlings were found. The Damaraland localities previously referred to, in which no Welwitschia seedlings have been found within recent years, are about forty miles from the sea.. But even in these southern latitudes normal seed-reproduction seems to occur on the coast. A recent letter from Dr. Hintrager, Acting Governor of German South-West Africa, contains the interesting statement that "wenige Kilometer nordöstlich von Cape Cross' die Welwitschia noch häufig und in fast allen Alterstadien, also auch in jungen Pflanzen vorkommt." It is not improbable that a condition of its seed-germination in nature is a degree of atmospheric humidity which is constantly realised near the sea though now usually absent from desert places inland.

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FIG. 1.-A glade in the Bauhinia forest showing a Baobab just before the beginning of leaf-fall

to an elevation of 4000 feet. Within this zone is the historic locality of Golungo Alto, where Welwitsch lived for two years, and in which a large part of his rich collection was obtained. Here he discovered Gnetum africanum in 1855.

A few miles to the south-east of Queta, a station on the railway within the forest zone and not far from its eastern edge, is situated the Government experimental plantation (Granja San Luiz), under the energetic direction of Mr. J. Gossweiler, to whom I am indebted for valuable advice and assistance during my residence there from April 1-12. The forests are here very dense and the undergrowth thick and very varied in character. After an unsuccessful search of some days' duration, Gnetum was eventually found on April 7 in a very dense and dark forest on the coffee and rubber estate of Montobello (2600 feet), some thirty miles to the west of Granja San Luiz and ten miles south west from the railway station of Queta. It was very abundant within a strictly limited area and its occurrence is clearly sporadic, as described by Welwitsch. It may be noted that the native name "N-coco given by Welwitsch is now applied indifferently to various plants of climbing habit; of Gnetum itself the natives seem to have no special knowledge.

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Leaving Loanda on April 16, I arrived on April 21 at Mossamedes, where the third section of the journey commenced. Quite exceptional rains had recently

On April 27 I left Mossamedes with the intention of crossing the Huilla plateau and reaching the Cunene River. I was accompanied by Mr. H. G. Mackie, H.B.M. Consul in Angola, to whose kind support the success of this part of the journey was very largely due. The light railway, at present working to the 107th kilometre, leaves Mossamedes in a northerly direction and crosses the broad beds of the periodical rivers Bero and Giroual, in which, near the sea,

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FIG. 2.-Cunene marshes opposite Fort Roçadas, looking north.

fallen here, as in so many other districts to the south, and the gently rising plains behind the town resembled a waving cornfield rather than a desert. They supported a thick, uniform growth of a tall Aristida (? A. prodigiosa, Welw.), among which there flourished a considerable number of small annuals. In sandy places, especially in shallow, dry 1 The first article appeared in NATURE of October 14.

a few tropical and subtropical crops are cultivated. So far inland as the present railhead, the rainfall is small and inconstant and, in normal seasons, the country is practically waterless. At about 80 km., however, the typical desert vegetation mingles with shrubs and a few dwarf trees, which are found in greater luxuriance on the lower

1 Lat. 219 S.

slopes of the Chella Range. The railhead is situated in an open forest of stunted trees, among which Acacias, a Bauhinia and the Baobab are prominent, with wide, grass-covered glades. This formation extends to the lower slopes of the Chella Range becoming denser as it ascends until, near the summit, it effects a junction with a Savannah, the characteristic species of which include a number of Proteacea and other southern forms. The western face of the Chella Range rises sheer to some 3000 feet from the forest which clothes its base, above which the bedding planes of its grey, lichen-covered sandstone are plainly visible. Except for its great extent, the whole range bears a striking resemblance to Table Mountain as seen from Table Bay. Opposite Capangombe there is a gap, the entrance to a kloof up which winds a steep footpath to the top through an increasingly dense, dripping forest, with a magnificent undergrowth of maiden-hair and other ferns. Near the summit a tall Euphorbia with the habit of E. grandidens occurs in great abundance.

On

Leaving the Boer village of Humpata (6000 feet) on May 10, we approached the Cunene along the now wellknown track down the valley of the Caculovar. descending the eastern slopes, which are less steep than the western, we passed through the same changes of flora, in the reverse order, as those already observed

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The country at its foot is thickly studded with small Baobabs and away to the east the open Acacia and Bauhinia forest again prevails, and undoubtedly merges farther south into the thorn-bush of Ovamboland and the Acacia park-formation which extends fat to the south of Okahandya and Windhuk.

I take this opportunity of acknowledging the effective support which has been very kindly given to the objects of the expedition by Their. Excellencies Sr. Capt. H. de Paiva Couceiro, Acting Governor-General of Angola; Herr Regierungsrath Dr. Hintrager, Acting Governor of German South-West Africa; and the Hon. W. F. HelyHutchinson, G.C.M.G., Governor of Cape Colony. H. H. W. PEARSON.

Quhita
May 13

MODERN METHODS OF ILLUMINATIONA

A GREAT change has come over the methods of lighting within the last few years. We have now at our disposal means of lighting which would have seemed incredible a few years ago. Step by step with these developments has taken place the progress of education and the increase of printed matter, with the result that we use our eyes to-day far more than in the past. Our main object, therefore, should be to consider the subject of illumination from the point of view of the impression received through the eye. After emphasising this aspect of illumination, Mr. Gaster proceeds with a summary of recent developments in electric lighting.

Gamlos

May 15

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Ovamboland

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Houmbe

the other side. Passing the Huilla Missionthe scene of the botanical labours of Fathers Antunes and Dekindt-we arrived on May 13 at Chibia (4500 feet), where the proteaceous flora thins out and gives place again to the open, dry forest, in which the Bauhinia and Acacias in turn predominate. Henceforward the surface, frequently broken by tumbled heaps of gneiss and ironstone, 50 feet to 500 feet high, slopes gently down to the Cunene. From Gambos (4100 feet) the water-supply, after the end of the rainy season (April), is meagre and its quality bad, and the whole district is fever-stricken. The temperature becomes very high after mid-day, and whirlwinds of great violence spring up very suddenly, and carry columns of dust and other light objects to great heights. Three hours by waggon from Houmbe brought us to the Cunene marshes, which are here confined to the right bank of the river. Owing to the unusually late rains they were still nearly two miles wide, and it was with great difficulty that a crossing to Fort Roçadas on the opposite bank was effected. This stronghold is placed upon the high calcareous cliff forming the left bank of the river. Its neighbourhood, the scene during recent years of many engagements between the Portuguese and the trans-Cunene Ovambo tribes, has become so extremely unhealthy that it will in future be manned entirely by native troops.

Cunene River

Fr Rocadas May 21

FortugueseFrontier.

Electric Glow-lamps.

It has long been known that a carbon filament glow-lamp could be made to yield more efficient results by bringing it to a higher temperature, i.e. running it at a pressure higher than that ordinarily utilised, but such a gain in efficiency has only been found possible at the expense of life and durability.

Within the last few years we have seen the development of lamps with filaments made of other and more refractory materials, such as the Nernst lamp, and the various metallic filaments, such as osmium, iridium, tantalum and tungsten, &c. The two lastnamed lamps, of course, now play a great rôle in electric lighting.

In addition, attempts have been made to improve carbon filaments in the United States by the graphitising process of Mr. Howell, by the aid of which a consumption of 2.5 watts to 3 watts per candle was attained. Another interesting attempt in this direction is the Hopfelt lamp, in which the carbon filament burns in an atmosphere of mercury vapour, with, it is stated, a consumption near 1.5 watts per candle. The Helion lamp, again, is believed to utilise a filament mainly composed of silicon; it is claimed to run for 1000 hours at 1 watt per candle, and even in the open air, without requiring to be enclosed in an evacuated globe; but it has not yet come 'upon the market. Perhaps the best known metallic filament lamps in use at the present day are those utilising the metal tantalum and those described by various names, but generally believed to contain as the main constituent the metal tungsten. Tungsten lamps are burned at a consumption approaching I watt per candle-power, and are generally stated to have a life, under good conditions, of 1000 burning hours. One great difficulty, however, has been the manufacture of lamps of moderate candle-power for high voltages, and capable of being used in any position; very recently, however, lamps having as low a candle-power as 25 or 30, and for pressures extending to 200 volts to 260 1 Abstract of a series of four Cantor lectures delivered by Mr. Les Gaster before the Royal Society of Arts and published in the Journal of the Society for August 6, 13, 20, 27; September 3, 10.

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