camp with his heavy luggage, that the lost party had set out from the Dumala Valley in the Bezingi District, with the hope of climbing Dychtau, 16,880 feet, from the south-east. Karaoul, at the head of the Cherek Valley, was made, therefore, the headquarters of the search party. They bivouacked under a rock beside the Tutuin Glacier, at a height of 9400 feet. Next morning (July 29) they started at dawn, and forced, not without difficulty, a passage through the monstrous séracs of the Tutuin Glacier. Above them they found a long snowy corridor leading to the base of Dychtau, and to the foot of a gap in its east spur, which they believed Mr. Donkin and his companions had crossed from the Dumala glen on the further side. Nothing was found at the foot of the steep rock wall, 1400 feet high, which protected the pass. The searchers therefore climbed the rocks

leading to it, and when 1000 feet above the snow and some 400 below the ridge, the traces sought were met with. The leader at the rope's end suddenly stopped short and gasped, "See, here is the sleeping-place." Before our eyes rose a low wall of loose stones built in a semicircle convex to the lower precipice. A crag partially overbung it; any object dropped over the wall fell 1000 feet on to the snow plain below. The space, some 6 feet square, inside the wall, was filled with uneven snow or ice, from which portions of knapsacks and sleeping bags protruded. A black stew-pan, half full of water, in which a metal cup floated, lay against the rock; a loaded revolver was hung beside it. It cost more than three hours' hard work to dig out all the objects from the frozen stuff in which they were embedded. Only three could work at once in the narrow space, and Mr. Freshfield and Mr. Woolley went on to the ridge, where they found a small stoneman, but no written record. Some manuscript notes and maps of Mr. Fox's were found in the bivouac, but nothing written after leaving the lower camp. The whole of the cliff and cliff's foot were carefully searched with a strong telescope. Mr. Woolley and his guides twice passed along the cliff's foot on his ascent of Dychtau, and he made certain that the party had not climbed the peak-that the accident therefore had happened on the ascent. After the lecture, Mr. Freshfield showed in the lantern a series of views of the Caucasus, from photographs by Mr. Hermann Woolley and Signor V. Sella. A complete set of Signor Sella's views, embracing eight panoramas and 90 views, was shown in an adjoining room. The panorama from Elbruz shows the whole chain of the Caucasus above a sea of clouds, and is probably the finest mountain photograph yet exhibited.

THE last issue of the Izvestia of the Russian Geographical Society is more than usually interesting, as it contains detailed letters received from the members of the three Russian expedi tions now engaged in the exploration of Central Asia. The letter of M. Roborovsky, dated August 16, and written in the highlands to the south of Yarkend, contains a most vivid description of the journey from the town Prjevalsk to Yarkend, across the passes of Barskaun and Bedel. M. Roborovsky knows Central Asia well, as he was Prjevalsky's travelling companion during three of his great journeys; and his descriptions of the country-its orography, climate, and flora-are full of most valuable information. Another letter is from M. Bogdanovitch, the geologist of the expedition, who joined it at Yarkend, after having crossed the Kashgarian Mountains on another route and explored the Mustagh ata glaciers. That part of the Pamir border-ridge had already been explored by Stoliczka, but M. Bogdanovitch adds much new information. It appears as might have been expected from the orography of the region-that there is no trace of mountains running north and south on the eastern edge of the great Pamir plateau. The Kashgar Mountains are an upheaval of gneisses, metamorphic slates, and Tertiary deposits, running from north-west to south-east. The limestones which Stoliczka supposed to be Triassic, proved to be Devonian. The most characteristic fossils of the Upper Devonian (Atrypa reticularis, A. latilinguis, A. aspera, Spirifer Verneuli, and several others) were found together with the corals (Lithodendron), Stromatopora and Ceriopora described by Stoliczka. The Tertiary sandstones are broken through (as is often the case in Siberia) by dolerites of volcanic origin, at the very border of the plateau, on its slope turned towards Kashgaria. Another series of letters, the last of which is dated September 23, from the sources of the Aksu, is from Colonel Grombchevsky. The late spring delayed the advance of the expedition, which spent the first part of June in crossing the Alai Mountains. The great Alai Valley of the Pamir could be reached only on June 19, but the Trans-Alai Mountains were buried in snow; no passage was

possible, and the explorer was compelled to march to the lowe tracts of Karategin. He thence proceeded to Kala-i-khuma little town situated on the Pendj, at a height of 4500 fee, 27 enjoying a relatively mild climate. From Kala-i-klum V Grombchevsky succeeded in reaching the Vantcha riverhaving met there the Afghan troops which were taking possess of the khanates of Shugnan and Rothan, he could not move further south, nor explore the western parts of the Pamir; he proposed to continue the exploration of the eastern parts of the Roof of the World. Finally, the two brothers, Grum Gezimziła who are exploring the Eastern Tian-Shan from Kaldja * Urumtsi, give short news of their progress, and remark that o maps of Eastern Tian-Shan are quite incorrect—a circumstan which might have been guessed from the general orographical structure of Central Asia. The collections of vertebrates as insects which have been gathered by the two explorers exceedingly rich.

A PERMANENT Marocco museum is to be established at the head-quarters of the Society of Commercial Geography : Berlin.

SMOKELESS EXPLOSIVES?

II.

So far as smokelessness is concerned, no material can surța gun cotton pure and simple; but, even if its rate of combust. in a firearm could be controlled with certainty and uniforanty although only used in very small charges, such as are require. for military rifles, its application as a safe and reliable propa agent for military and naval use is attended by so many diffic ties, that the non-success of the numerous attempts, made it the first twenty-five years of its existence, to apply it in th direction, is not surprising.

Soon after its discovery by Schönbein and Bottger in 18 endeavours were made to apply gun-cotton wool, rammed in Subsequently von Lenk, who made the first practical approac cases, as a charge for small arms, but with disastrous result to the regulation of the explosive power of gun-cotton, producs small-arm cartridges by superposing layers of gun-cotton threads system of regulating the rapidity of burning of gun-cotton, 25 these being closely plaited round a core of wood. Von Lenk to suit it either for gradual or violent action, consists, in fact, converting coarse or fine, loosely or tightly twisted, threads rovings of finely carded cotton into the most explosive form gun-cotton, and of arranging the e threads or yarns in different ways so as to modify the mechanical condition, the compac ness and extent and distribution of enclosed air-spaces, of the mass of gun-cotton composed of them. Thus, small-arm cartrige were composed, as already stated, of compact layers of tightly plaited, fine gun-cotton thread; cannon cartridges were made of coarse, loose gun-cotton yarn wound very compactly upon core; charges for shells consisted of very loose cylindrical hollow plaits (like lamp wicks), along which fire flashed almost instan taneously; and mining charges were made in the form of very tightly twisted rope with a hollow core. While the tw latter forms of gun-cotton always burned with almost instin taneous rapidity in open air, and with highly destructive effec if they were strongly confined, the tightly wound or pla masses burned slowly in air, and would frequently exert the explosive force so gradually when confined in a firearm 18 to produce good ballistic results without appreciably destructive effect upon the arm. Occasionally, however, in consequence of some slight unforeseen variation in the compactness of the material, or in the amount and disposition of the air-spaces t the mass, very violent action would be produced, showing that this system of regulating the explosive force of gun-cotton was quite unreliable.

Misled by the apparently promising nature of the earliest results which von Lenk obtained, the Austrian Government er barked, in 1862, upon a somewhat extensive application of ro Lenk's gun-cotton to small arms, and provided several battene of field guns for the use of this material. The abandonmen' these measures for applying a smokeless explosive to miluar purposes soon followed upon the attainment of unsati-factors results, and was hastened by the occurrence of a very destructiv

Friday Evening Discourse delivered by Sir Frederick Abd, FRS, 2 the Royal Institution of Great Britain, on January 31, 1994 Coins from p. 330.

the Rottweil powder-works, and appears to have been adopted into the German service for a time, but its first great promise of success seems to have failed of fulfilment through defects in stability.

Reference has already been made to the conversion of guncotton (trinitrocellulose), and to mixtures of it with less explosive forms of nitrated cotton (or nitrated cellulose of other description), by the action of solvents into horn-like materials. These are in the first instance obtained in the form of gelatinous masses, which, prior to the complete evaporation or removal of the solvent, can be pressed or squirted into wires, rods, or tubes, or rolled or spread into sheets; when they have become hardened, they may be cut up into tablets or into strips or pieces of size suitable for conversion into charges or cartridges. Numerous patents have been secured for the treatment of guncotton, nitro-cotton, or mixtures of these with other substances, by the methods indicated; but in this direction the German makers of the powder just now referred to seem to have secured priority. Experiments were made about a year and a half ago with powder produced in this way at Woolwich, and the Wetteren Powder Company in Belgium has also manufactured socalled paper powders, or horn-like preparations, of the same kind, which were brought forward as counterparts of the French small-arm and artillery smokeless powder.

Mr. Alfred Nobel, to whom the mining world is so largely indebted for the invention of dynamite, and of other very efficient blasting agents of which nitro-glycerine is the basis, was the first to apply the latter explosive agent, in conjunction with one of the lower products of nitration of cellulose, to the production of a smokeless powder. The powder bears great resemblance to one of the most interesting of known violent explosives, also invented by Mr. Nobel, and called by him blasting gelatine, in consequence of its peculiar gelatinous character. When the nitro-cotton is impregnated and allowed to digest with nitro-glycerine, it loses its fibrous nature and becomes gelatinized while assimilating the nitro-glycerine, the two substances furnishing a product which has almost the character of a compound. By macerating the nitro-cotton with from 7 to 10 per cent. of nitro-glycerine, and maintaining the mixture warm, the whole soon becomes converted into a plastic material from which it is very difficult to separate a portion of either of its components. This preparation, and certain modifications of it, have acquired high importance as blasting agents more powerful than dynamite, and possessed of the valuable property that their prolonged immersion in water does not separate from them any appreciable proportion of nitro-glycerine.

In the earlier days of the attempted application of blasting gelatine to military uses, in Austria, when endeavours were there made to render the material less susceptible of accidental explosion on active service (as by the penetration of bullets or shell fragments into transport waggons containing supplies of the explosive), this result was achieved by Colonel Hess by incorporating with the components a small proportion of camphor, a substance which had then, for some time past, played an inportant part in the technical application of nitro-cotton to the production of the remarkable substitute for ivory, horn, &c., known as xylenite. By incorporating with nitro-glycerine a much larger proportion of nitro-cotton than used in the produc tion of blasting gelatine, and by employing camphor as an agent for promoting the union of the two explosives, as well as, apparently, for deadening the violence, or reducing the rapidity of explosion of the product, Mr. Nobel has obtained a material of almost horn-like character, which can be pressed into pellets or rolled into sheets while in the plastic condition, and which compares favourably with the gun cotton preparations of somewhat similar physical characters just referred to, as regards ballistic properties, stability, and uniformity, besides being almost absolutely smokeless. The retention in its composition of some proportion of the volatile substance camphor, which may gradually be reduced in amount by evaporation, renders this explosive liable to undergo some modification in its ballistic properties in course of time; it is believed that this point has been dealt with by Mr. Nobel, and accounts from Italy speak favourably of the results of trials of his powder in small arms, while Mr. Krupp is reported to be carrying on experiments with it in guns of several calibres.

The Government Committee on Explosives, in endeavouring to remedy the above defect of Nobel's original powder, were led by their researches to the preparation of other varieties of nitroglycerine powder, which, when applied in the form of wires or

rods, made up into sheaves or bundles, have given, in service small-bore rifle, excellent ballistic results. The n promising of them, which fulfils, besides, the conditions of lessness and of stability, so far as can be guaranteed by application of special tests of exposure to elevated temperature. &c., is now being submitted to searching experiments with view of so applying it in the arm as to overcome certain diffical, attending the employment, in a very small-bore riffe, of 11 explosive developing much greater energy than the black powe charge, which therefore gives very considerably higher veloces even with much smaller charges, and consequently hea arm much more. Thus, the service black powder chan furnishes, with the small-bore rifle, an average (and vant velocity of 1800 f.s., together with pressures ranging from 1520 tons per square inch; on the other hand, with consideral less of the powder referred to, there is no difficulty in se a very uniform velocity of about 2200 f.s, with pressures de exceeding 17 tons, while velocities as high as 2500 fs, J obtainable with pressures not greater than the maximum all with the black-powder charge.

a

It is obvious, from what has already been said respecting causes of the erosive action of powder in guns, that compare tively considerable erosive effects would be expected ic produced by powders of high energy as compared with powder. Moreover, the freedom of the products of explos from any solid substances, and consequently the absence of a fouling or deposition of residue in the arm, causes the het surfaces of the projectile and of the interior of the tar remain clean, and in a condition, therefore, very favoortide close adherence together. If to these circumstances hea the fact that the behaviour of the smokeless powder bas adapted to suit an arm, a cartridge, and a projectile origita designed for use with black powder, it will be understood the devising of an explosive which shall be practically smokice sufficiently stable, and susceptible of perfectly safe use i arm under all service conditions, easy of manufacture, ana too costly, is, after all, but a small part of the difficult pro of adapting a smokeless powder successfully to the new mirr rifle-a problem which, however, appears to be on the re approach to satisfactory solution.

The experience already acquired in guns ranging in calilve from 185 inches to 6 inches, with the smokeless powder de for use in our service, has been very promising, and indee that the difficulties attending its adaptation to guns designed black powder are likely to prove considerably less than in ' case of the small arm. But here, again, the circumstances m much smaller charges are required to furnish the same bail as the service black-powder charges, and that the compara gradual and sustained action of the new powder gives rett lower pressures in the chamber of the gun, and higher pres along the chase, demonstrate that the full utilization of the t listic advantages, and the increase in the power of guns! given calibre and weight with the new form of powder, are wh attainable by some modifications in the designs of the ga such as a reduction in size of the charge-chamber, and s additions to the strength, and perhaps, in some cases, of length, of the chase.

When, however, the smokeless powder has been adapted *. * success in all respects to artillery, from small machine-guns guns of comparatively heavy calibre, and when its balliste vantages have been fully utilized in guns of suitable desgr will remain to be determined how far such a powderniably of much more sensitive constitution than black pow or any of its modifications-will withstand, unchanged unharmed, the various vicissitudes of climate, and the storage-conditions in ships and on land in all parts of the w -a condition essential to its adaptability to naval and milita use, and especially to the service of our Empire; and whe sufficient confidence can be placed in its stability for long per under these extremely varied conditions to warrant the nece•27° freedom from apprehension of possible danger, emanating within the material itself, to allow of its being substitute!* black powder wherever its use may present advantages.

Possible it might be, that the storage, with perfect safety such a powder in ships, forts, or magazines might desthe adoption of precautionary measures tending to pa comparatively narrow limits upon the extent of its practica service applications; even then, however, an imperative need the introduction of special arrangements to secure salir immunity from deterioration may be of small importame a

mpared with the great advantages which the provision of a horoughly efficient smokeless powder may secure to the possessor it, especially in naval warfare.

That the opinions re-pecting the importance of such advantages re founded upon a sound basis, one can hardly doubt, after the =iews expressed by several of the highest military and naval authorities, although opinions as to their extent may differ very Considerably even among such authorities.

The accounts furnished from time to time from official and ivate sources of the effects observed, at some considerable ivance, by witnesses of practice with the smokeless powders cessively adopted in France, have doubtless been regarded by untary authorities as warranting the belief that the employment of such powders must effect a great revolution in the conduct of mpaigns. Not only have the absence of smoke and flame een dwelt upon as important factors in such a revolution, but he recorders of the achievements of smokeless powder-whose escriptions have doubtless been to some extent influenced by e vivid pictures already presented to them of what they should ncpate-have even been led to make such explicit assertions as to the noiselessness of these powders, that high military thorities have actually been thereby misled to portray, by id word-painting, the contrast between the battles of the ure and the past ;-to imagine the terrific din caused by the charge of several hundred field-guns and the roar of musketry the great battles of the past, giving place to noise so slight hat distant troops will no longer receive indications where their nrades are engaged, while sentries and advanced posts will no ger be able to warn the main body of the approach of an ny by the discharge of their rifles, and that battles might ly be raging within a few miles of columns on the march hout the fact becoming at once apparent to them. It is somewhat difficult to conceive that, in these comparatively -lightened days—an acquaintance with the first principles of vical science having for many years past constituted a preinary condition of admission to the training establishments of The future warrior—the physical impossibility of such fairy tales *appear to be considered necessary in France for the delusion the ordinary public, would not at once have been obvious. **t, even in professional publications in Germany, where we led to expect that the judgment of experts would be comaratively unlikely to be led astray through lack of scientific Towelge, we have, during the earlier part of last year, read, a. ticles upon the influence of smokeless powder upon the art vir (based evidently upon the reports received from France), passages as these:-"The art of war gains in no way as simplicity is concerned; on the contrary, it appears to us at the absence of so important a mechanical means of help as *ur and smoke were to the commander, requires increased skill - circumspection in addition to the qualities demanded by a meral. "The course of a fight will certainly be mysterious, on account of the relative stillness with which it will

De carried on."

In an amusing article, in imitation of the account of the Battle 4 Dorking, which appeared in the Deutsche Heeres Zeitung of Apn! last, the consternation is described with which a battalion eceives the information from a wounded fugitive from the out

that the enemy's bullets have been playing havoc among em, without any visible or audible indications as to the quarter attack. Later in the year, and especially since the manoeuvres efore the German and Austrian Emperors, when the employat of the new smokeless powder was the event of the day, absurdity of the assertions as to the noiselessness of the new wders became a theme for strong observations in the German re papers; the assumed existence of a noiseless powder was eled as a thing equally impossible with a recoil-less powder; be violence of the report, or explosion, produced upon the disharge of a firearm being in direct relation to the volume and nsion of the gaseous matter projected into the surrounding

The circumstance that blank ammunition was alone used in he smokeless powder exhibition at the German manoeuvres, may have serveil to lend some support to the assertions as to parativ ly lule noise made by the powder-the report of ank carndges being slight, on account of the small and lightly onfined charges used. It is said that the sound of practice with black ammunition at the German manoeuvres, was scarcely regated at a distance of 100 metres. In a recently published pamphlet on the results of employment of the latest German okeless powder in the manoeuvres, it is stated, on the other

hand, that the difference between the violence of the report of the new powder and of black powder is scarcely perceptible: that it is sharper and more ringing, but not of such long duration. This description accords exactly with our own experience of the reports produced by different varieties of smokeles powder, and of the lecturer's earlier experience with gun-cotton charges fired from rifles and field guns. The noise produced by the latter was decidedly more ringing and distressing to the ear in close proximity to the gun, but also of decidedly less volume than the report of a black-powder charge, when heard at a considerable distance from the gun.

As regards smokelessness, the present German service powder is not actually smokeless, but produces a thin, almost transparent, bluish cloud, which is immediately dissipated. Independent rifle-firing was not rendered visible by the smoke produced at a distance of 300 metres, and at shorter ranges the smoke presented the appearance of a puff from a cigar. The most rapid salvo-firing during the operations near Spandau did not have the effect of obscuring those firing from distant observers.

That, in future warfare, if smokeless or nearly smokeless powders have maintained their position as safe and reliable propelling agents for small arms and field artillery, belligerents of both sides will be alike users of them, there can be no doubt. The consequent absence of the screening effect of smokewhich, on the one hand, removes an important protection and the means of making rapid advances or sudden changes of position in comparative safety, and, on the other hand, secures to both sides the power of ensuring to the fullest extent accuracy of shooting, and of making deadly attack by individual fire through the medium of cover, with comparative immunity from detection can scarcely fail to change more or less radically many of the existing conditions under which engagements are fought.

As regards the naval service, it is especially and, at present at any rate, exclusively for the new machine and quick-firing guns that a smokeless powder is wanted; for such service the advantages which would be secured by the provision of a reliable powder of this kind can scarcely be over-estimated, and their realization within no distant period may, it is believed, be anticipated with confidence.

NOTE ON MR. MELDE'S VIBRATING STRINGS. THE effect of Mr. Melde's pretty experiments with the vibrating stretched thread attached to one of the prongs of a tuning-fork is often spoiled to the spectators by the unfavourable plane of vibration assumed by the thread. A very simple device removes this inconvenience, and enables the operator to suit his own choice for the plane of vibration. The accompanying sketch sufficiently explains itself, and shows the arrangement for restricting the vibrations to the vertical plane.

B

Instead of attaching the end of the thread to the prong of the tuning-fork, it is tied to the middle of a short thread dae, and the ends d and e of this are attached to the prong in a vertical line. It is clear that if the distance of A from the line de is an appreciable part of the quarter wave-length of the vibration, and AB is an integral multiple of the half wave-length, vibration is possible only in the vertical plane. For in the horizontal plane this rate of vibration is impossible, A being not a fixed point of the thread for vibration in this plane, and the length from the prong to the pulley being not an integral multiple of the half wave-length of vibration. And in any other plane the vibration, if possible, would be compounded of two, viz. of the vertical which is possible and of the horizontal which is impossible.

The most convenient form of fixture for the short thread dac, is a light steel wire with an eye at each end, lashed to the prong