5.45 a.m., although the shock started from the focus, 1280 kilometres away, at 6.10, they examined their data with due scientific caution, and so discovered that the local time-standard of Bombay accounted for the apparently negative result; but as they obtained from their newspaper a positive record for the Calcutta seismograph, the application of the same system of scientific criticism of the time-standards did not occur to them. As a consequence, they arrive at the astonishing result that, whilst the earthquake waves travelling southwards to Bombay had a speed of 4.266 kilometres a second, those which were transmitted south-eastwards had a speed of 0.700 kilometres only.

The rest of the paper consists of "facts and inferences" of this kind, and whilst most are unimportant, it is desirable, perhaps, to point out that the epicentre determined by the authors is far removed from the true

one.

They have had to stretch their epicentre for more than forty miles to the west to account for the " complete destruction" of Pathankot. I was at Pathankot soon after the earthquake, and found it difficult to discover even a masonry crack in the town; even a few more newspaper cuttings would have shown the authors that the place was practically undamaged.

After picking a few pebbles out of this conglomerate of truth and fiction, one wonders why the paper was ever published at all. The very newspaper from which they obtained their data must have informed the authors that a thorough investigation of the earthquake had been organised by the Geological Survey. As both authors were in Madras at the time, one would imagine that a subject sufficiently interesting for a serious paper in a leading scientific journal would be worth, at any rate, a few more newspaper cuttings, even if a personal visit to the affected area were thought to be, for private reasons, inconvenient. We take it for granted that the long experience of both authors must have brought them into contact with the etiquette observed by scientific men, and that neither would consciously risk the recognised danger of forestalling the results of a thorough investigation by the publication of conclusions obtained from unverified data. But whatever the object, if the editor of a leading scientific journal can join in the production of such a paper, the future of scientific literature in Germany may yet give us entertainments as surprising as any of the recent efforts of the Russian Navy.

Of the Kangra earthquake, as well as of the other Indian questions which have been treated recently in the Centralblatt with an equal regard for accuracy, those who wish to know the truth will be provided with details in due season. Within a few days after the disaster occurred, every telegraph operator, meteorological observer, and district official north of the latitude of Bombay was provided with a complete guide for reporting the resulting phenomena, and the reports so obtained have since been supplemented by a detailed examination of the affected area by five officers of the Geological Survey. The observations made will be summarised first in the next part of the records, and the full details will form a special memoir, now in course of preparation. When these reports are ready, it will be seen that the actual facts, though in ways interesting and novel, are scarcely so strange as German fiction. T. H. HOLLAND.

Now, both W and ǹ are known in terms of the velocity and acceleration of the charge at any moment by formulæ I gave in NATURE, October 30, November 6, 1902. But when applied to (1), (2), these equations do not let us determine M generally in terms of the velocity and acceleration, on account of the variability of the state of the field, and the waste of energy and momentum. M is indefinite. But in long-continued forced circular motion of a charge, Ü+T=o. So

This is the transverse momentum of Q in steady circular motion, without any limitations upon the size of the velocity and acceleration, save the usual ones, u<v, and a not excessively great in regard to the diameter of the electron.

It would seem that an integration over the whole field, in which E and H are known (loc. cit.), is required to find M,, the direct momentum. If, however, the acceleration is infinitesimal, the known formula for M, in steady rectilinear motion may be employed, viz. M1u=T.

Finally, I have pleasure in saying that Mr. G. F. C. Searle, F.R.S., led me to see that my waste formulæ led to the formula (9) for the transverse momentum, by submitting to me a calculation of M, in the special case of infinitesimal acceleration and velocity. He made no use of the waste formula, not being aware of it, but, since in the circumstances the waste is infinitesimal, it did not matter. In fact, M,u=T leads to the reduced special value of the transverse momentum when u and a are infinitesimal. The argument became somewhat obscure by the want of comprehensiveness, but the result agrees with (9). OLIVER HEAVISIDE. August 20.

A Parasite of the House-fly.

I SHOULD be very glad if Mr. Hill (p. 397) would send me a few specimens of the Pseudoscorpiones he has found attached to common house-flies, and I will endeavour to identify them for him. There are several genera of this order represented in the British fauna, and it is probable that all the species occasionally attach themselves to the legs or wings of larger insects and arachnids. There is some doubt, however, whether this is a case of true parasitism. It may be that the occasional association of these small arachnids with larger and more rapid arthropods is of importance to the species in providing a means for a wider geographical distribution.

SYDNEY J. HICKSON. The University, Manchester, August 25.

introduction of restrictive legislation has not removed all the difficulties incident to the successful protection of cockle and mussel beds where the beds do not form part of a several fishery, that is to say, are under private ownership. Restrictive methods such as the abolition of destructive implements of fishing and the prevention of the removal of cockles and mussels under a certain size, no doubt do protect beds from excessive depletion, but there are various factors which require other treatment for their solution. In some districts, notably at Morecambe, beds have become overcrowded, SO that thinning is an absolute necessity. In one instance the present writer counted 116 small mussels adhering to an area of one square inch. In other cases there is the danger that the molluscs may become smothered by sand, or that the "spat " has struck too near the high-water mark for the mussels to develop to the size at which they may legally be taken by the fishermen. Three years ago the scientific subcommittee of the Lancashire Sea Fisheries District expended a small sum of money in order to try the experiment of thinning the Morecambe mussel beds. The shellfish that were removed were transplanted to other suitable areas nearly or entirely bare of shellfish.

Samples of the mussels were taken before and at frequent intervals after transplantation. It was found that the experiment was successful, and in the following year (1904) the work was extended to other districts on the Lancashire coast, and attention was not only directed to mussels, but cockles were transplanted from overcrowded beds in the neighbourhood of Southport. This year the experiment has been proceeded

with still further. Cockles have been transplanted successfully at Lytham and Southport, and mussels at Morecambe, Flookburgh, and in the Wyre and Lune estuaries. The work is carried out under the superintendence of the committee's bailiffs, and the shellfish gatherers are paid per tide for the work involved as well as for hire of boats. The mussels are

generally removed at the commencement of the close season-which lasts in this district from April to August inclusive so that the fish have a chance of accommodating themselves to their new environment without disturbance. Care is also taken to remove shellfish under the legal size so that their growth can be tested before they become "sizeable" fish for the market. The renewed growth which takes place in old cockles and mussels which had previous to removal not grown for years is remarkable.

The amount of shellfish transplanted is in the aggregate considerable, as may be seen from the following. In four days at Morecambe alone 152 tons 11 cwt. of mussels were re-deposited in localities favourable for their vigorous growth. At Lytham undersized cockles were removed from places where they were left dry too long by the receding tide, as a consequence of which their growth was checked, to more suitable ground where their growth was likely to be facilitated. This work is rendered possible by the Sea Fisheries (Shell Fish) Regulation Act of 1894, which inter alia provides that a local fisheries committee shall have power to stock or re-stock any public fishery for shellfish, and for that purpose to incur such expenses as may be sanctioned by the Board of Agriculture

FIG. 2.-At work with the "Craam.'

and Fisheries. The fishermen themselves, who may invariably be trusted to express their criticism of any work undertaken by the committee in a frank and outspoken manner, in this case express their appreciation of the efforts of the committee to improve and maintain the shellfish industry on the Lancashire coast. The value of the cockle industry to the Lancashire cocklers is approximately 20,000l. per annum.

THE STANDARDISATION OF SCREWS.

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THE question of standardising screw threads and limit gauges has long received the careful attention of engineers, and in Great Britain considerable advantage has accrued from the publication of an interim report (No. 20, April, 1905) of the Engineering Standards Committee, dealing with the form and pitches of screw-threads most suitable for general engineering purposes. Having regard to the fact that the Whitworth thread is in general use throughout the country, the committee does recommend any departure from this form of thread. The existing Whitworth series of pitches for screws from inch to 6 inches in diameter does not, however, satisfy all requirements, and the committee has drawn up tables of standard sizes which will doubtless meet with general adoption. For all sizes of screw threads below inch in diameter the committee recommends the adoption of the pitches, sizes, and form of thread proposed by the British Association Small Screw Gauge Committee in 1884. In France an influential committee of the Société d'Encouragement pour l'Industrie nationale, consisting of General Sebert and Messrs. Carpentier, Sauvage, Masson, Sartiaux, and Zetter, has devoted attention to the subject, and has published in the current issue of the Bulletin of the society a scheme for extending the international system to screws of less than 6 millimetres in diameter. The committee recommends the adoption, between the diameters of 1 millimetre and 5.5 millimetres inclusive, of twelve screws as shown in the following table :—

The six largest screws of this series are those first proposed by the second committee of the Chambre syndicale des Industries électriques. The screws of 2 millimetres and of 2.5 millimetres for which the pitch is 0.5 millimetre having proved too coarse, have received the pitch of 0.45 millimetre. The 1 millimetre screw has received the pitch of 0.25 millimetre in order to bring the new series into accord with the Thury series, which is used for very small screws. The scheme appears likely to be favourably received by the Swiss and German industries.

The initial accuracy of a helical surface, as distinct from the sectional form of the thread, is dependent upon the accuracy of the leading screw of the machine upon which it is cut, and thus the leading screw becomes a generating master-gauge which instead of being used solely for gauging is called upon to do work involving wear. The importance of maintaining the accuracy of these leading screws in connection with the production of the interchangeable parts of modern guns and gun mountings led to the appointment in November, 1900, of a committee consisting of Mr. H. F. Donaldson, chief superintendent of the Royal Ordnance Factories, president, Mr. R. Matthews, Lieutenant A. T. Dawson, R.N., Mr. H. J. Chaney, Dr. R. T. Glazebrook, F.R.S., and Colonel H. C. L. Holden, R.A., F.R.S., to consider the provision of standard leading screws for screw-cutting lathes, and its report to the secretary of the Army Council has just been published. The committee finds that the only practical way to obviate the difficulty found in securing absoIute interchangeability, even on short lengths of large screws, is to provide centrally special machinery for

the supply of large screws of certified accuracy. Approval of funds for this purpose was accordingly sought and obtained. The machine, which was made by Messrs. Armstrong, Whitworth and Co., of Manchester, was designed to secure accuracy over 3 feet length of screw. Measurements made after the machine was installed in the special chamber erected for it at the National Physical Laboratory showed that the movement of the tool carriage did not vary from that produced by a true screw of the same reputed length by more than 0.0002 inch in its full length, and after insertion of a correcting cam by more than 0.0001 inch at any one point, and that corrected microscopic scale readings and independent end-measure readings did not differ by more than 0.0001 inch at any point. The committee recommends that all accurate screws required for Government engineering work be supplied in future from screws originated from or corrected by the standard leadingscrew adjusting machine at the National Physical Laboratory, and that facilities be given to private firms to correct heavy screws of -inch pitch by this machine. The house in which the machine is installed at the National Physical Laboratory presents many points of interest, as the greatest possible precautions have been taken to maintain uniformity of temperature and freedom from vibration.

THE STERILISATION OF WATER IN THE FIELD.

T is well known that disease is more fatal to the IT soldier in a campaign than the bullets of the enemy. Thus in the South African campaign the total deaths from disease were almost exactly double those due to wounds in battle. The diseases which persistently dog the track of an army are typhoid or enteric fever, dysentery, and, in certain countries, cholera, and to these the principal mortality is due.

As regards their incidence, much necessarily depends on the climatic and physical conditions of the country in which the war is being carried on. Both in the Spanish-American war and in the South African war typhoid fever proved a terrible scourge.

These diseases are usually largely water-borne, but it must be recognised are not exclusively so, and, therefore, attention to the water supply alone will not wholly prevent them. In the SpanishAmerican war, for instance, the commission which investigated the typhoid fever epidemics of the United States Army reported that infected water was not an important factor in its spread. The other agents concerned in the dissemination of this disease are dust and flies, blowing or carrying infection from infected latrines, and gastro-intestinal disturbance, the result of heat, fatigue, and bad food rendering the troops more vulnerable. It cannot be doubted, however, that a pure water supply would do much to lessen the incidence of typhoid fever and dysentery, and probably quite prevent cholera.

A pure water supply can partially be secured by three methods; (1) by a careful selection of the camping grounds and protection of the water supply from pollution; (2) by deep-driven artesian wells; and (3) by the sterilisation of the water; or a combination of these methods may in many instances be adopted. But whatever method is applied it must be remembered that soldiers parched with thirst will drink any water that comes in their way. As regards the first method, the selection of the camping grounds, &c., it is reported that it has been adopted with considerable success by the Japanese in the present campaign; a corps of medical officers is sent on ahead to select The camping ground and survey the water supply;

sources which seem to be polluted can thus be largely excluded, and by judicious arrangement of the latrines and by posting guards to prevent individual pollution and the drinking of suspicious supplies much may be done to ensure pure water for drinking. As regards artesian wells, surface wells and streams are the main source of danger, but by driving deep artesian wells a pure water is obtained. This, however, would be possible only under special conditions in certain districts and for comparatively small contingents.

for the purpose. It may be put up in tablets, and in quantities of 15 grains to the pint or thereabouts destroys the typhoid bacillus in water within half an hour, imparts little or no taste to the water, and is quite harmless. Lastly, there is the method introduced lately by Lieut. Nesfield, I.M.S., in which chlorine is the sterilising agent, and this, after acting, is "killed" by the addition of sulphite of soda. For small quantities of water, iodine may be similarly used. This last method was recently described in NATURE (July 27, p. 307), and has much to commend R. T. HEWLETT.

PROF. JULES OPPERT.

(3) chemical germicides.

Filtration through a porcelain filter, if it can be applied, would be efficient, but it necessitates a good deal of apparatus, and the filter candles are fragile. It is a good method under efficient supervision, but is more applicable for small contingents than a large

army.

Heat has been adopted by many inventors, and Mr. Arnold-Forster, M.P., recently inspected a number of devices based on this principle. In most, e.g. the Lawrence, Forbes, Mallock, and Tuckfield and Garland machines, the water is heated to the boiling point, but in the Griffiths machine it is assumed (from experimental evidence) that heating to about 170° F. suffices, which results in a considerable economy in fuel. In all the machines the out-going hot water warms the in-going cold water, and is itself cooled thereby. Important considerations are weight and fuel, and these have received much attention from the respective inventors.

The Mallock machine, which, including pump and cases, weighed 153 lb., with a consumption of one pint of kerosine gave 50 gallons of water an hour at a temperature of 88° or 90°, the temperature of the ingoing water being 74°. The Tuckfield and Garland machine, of which the steriliser weighed 198 lb. and the heating apparatus 126 lb., gave 40 to 50 gallons at a temperature of between 104° and 110°, the temperature of the in-going water being 78°; its inventors state that it requires 20 lb. or 30 lb. of kerosine for 1000 gallons of water, and in it the water to be sterilised is heated by steam generated in a separate boiler. The Griffiths machine, weighing 120 lb. and using 1 pint of kerosine an hour, yielded 26 gallons of water an hour at a temperature of 92°, 45 gallons an hour at a temperature of 103° to 106, and 72 gallons an hour at a temperature of 105°, the temperature of the supply being in all cases 67 The Lawrence apparatus, weighing, with watertank and case, 168 lb., and working with supply water at 74°, had a temperature of delivery of 88° to 90°, but it used two pints of kerosine an hour and the quantity of water delivered was only 30 gallons an hour. Finally, the Forbes machine, weighing 130 lb., delivered 15 gallons of water an hour, with an oil consumption of one pint, the temperature of supply being 74°, and of delivery from 86° to 90°.

Lastly, there remain the chemical germicides. Obviously these must have no deleterious action on man in the quantities employed; they should not be corrosive to metal vessels, they should be portable and act rapidly. Alum has long been employed for purifying water, but its action is to clarify a turbid water, and it cannot be relied on to sterilise. Potassium permanganate may be used, but is not very efficient or trustworthy, and both it and alum necessitate the water being left for some hours. Some three or four years ago Parkes and Rideal introduced bisulphate of soda

of the band of great scholars who were the pioneers of cuneiform decipherment. His name will go down to posterity with those of Rawlinson, Hincks, de Sauley, and Fox Talbot, with whom he helped to lay the foundations of the flourishing science of Assyriology. Like them, too, he has now laid down the pen for ever.

Born of Jewish parents in Hamburg on July 9. 1825, Jules Oppert began the study of Sanskrit and Arabic under Lassen and Freytag at Bonn, afterwards devoting himself to Zend and Old Persian at Berlin and Kiel. In 1847 he published his first work, entiled "Das Lautsystem des Altpersischen," in which he discovered that m and n had to be supplied before a following consonant in Old Persian, and thereby supplementing the alphabet. At that time the German law did not permit Jews to hold professorial posts, so in the same year he moved to France, where he was appointed professor of German at Laval, and afterwards, in 1850, at Rheims. The favourable reception accorded to his work on the Achæmenian inscriptions obtained for him, in 1851, a post on the staff of the scientific mission dispatched to Mesopotamia by the French Government, under MM. Fresnel and Thomas.

On his return in 1854, Oppert devoted himself entirely to the study of Assyrian and Babylonian, and between 1857 and 1863 the several volumes of his great work 'Expédition scientifique en Mésopotamie saw the light. While the linguistic value of this has always been of the greatest importance, the topography is less fortunate, the late author having been led into the mistake that the ruins of ancient Babylon were much larger than they really are. In 1855 he visited the British Museum and the museums of Germany to report on the progress made in cuneiform studies, and on his return in the following year he was decorated with the Cross of the Legion of Honour, and obtained the post of professor of Sanskrit and comparative philology at the school of languages attached to the Imperial Library at Paris. Two years previously he had become a naturalised Frenchman. In 1859 he published a Sanskrit grammar, closely followed by "Eléments de la Grammaire assyrienne." In 1865 there appeared from his pen a short history of Babylonia and Assyria. In 1881 he succeeded the late M. Mariette as member of the Institute of France, being elected president of the same society ten years later--perhaps the highest honour a French savant can receive.

a

The versatility of the late Prof. Oppert was extraordinary. His papers, published in various scientific journals, cover an astonishing range of subjects. Not the least interesting are his contributions to astronomical chronology, in which subject he took a deep interest. In "La Chronologie biblique fixée par les Éclipses des Inscriptions cunéiforme" (Rev. Archeol., 1868) he attempted to reconcile the dates

monuments.

of the Old Testament with those of the Assyrian Other astronomical works are:-" Die astronomischen Angaben der assyrischen Keilinschriften" (Band xci., Kais. Akad. der Wissensch., 1885). "Un Annuaire astronomique babylonien, utilisé par Ptolémée (Journ. As., 1890), "Les Éclipses mentionnées dans les Textes cunéiformes (Zeitschr. für Assyr., 1897), and many others of less importance. One of his last works was a contribution to chronology, entiled "L'Année de Meton" (Rev. des Études grecques, 1903). In his early days he had been a great champion of the genuineness of cuneiform decipherment, when its opponents counted among their ranks such great men as Renan and many others. He was one of the historic four who, at the invitation of the sceptics, produced a translation of the cylinder of Tiglath-Pileser I., which was read at a meeting of the Royal Asiatic Society by the president, and found to be substantially the same as the translations of Rawlinson, Hincks, and Fox Talbot, all of whom had bound themselves over not to collaborate or communicate with one another.

NOTES.

AT the time of going to press, no message had been received from Sir Norman Lockyer as to the eclipse observations at Palma. The following telegram from the Astronomer Royal had, however, reached the Royal Society: Eclipse satisfactorily observed, but partially cloudy. Photographs with all instruments."

PROF. RONALD Ross informs us that the announcement to the effect that he has proceeded to New Orleans with Prof. Rubert Boyce, in connection with the outbreak of yellow fever there, is without foundation.

THE sixteenth annual general meeting of the Institution of Mining Engineers will be held at Manchester on September 13-16. The following papers will be read, or taken as read :-Leading features of the Lancashire coalfield extended: J. Dickinson; up-to-date electrical power distribution: R. L. Gamlen; can explosions in coal-mines, with their associated toxic fatalities, be prevented? B. H. Thwaite; earth in collieries, with special reference to the recently issued departmental rules: S. F. Walker; the value of mollusca in Coal-measure stratigraphy J. T. Stobbs.

THE Local Government Board has issued a circular to

borough councils and other local authorities respecting cerebro-spinal or "spotted" fever. This disease has recently been somewhat prevalent in Central Europe and in America, but the Board expresses the opinion that there has been no increase of the disease in England. For the guidance of local authorities the chief features of the disease are detailed, and, should an outbreak occur, the Board is prepared to advise the authority respecting it and to sanction notification.

DURING the past week the weather over the British Islands has been very unsettled; on Thursday last, heavy rain set in over many parts of Ireland, and continued almost without interruption for about thirty-four hours. The amounts measured during this period were 4-17 inches at Greystones, 4:33 inches at Dublin, 4.71 inches at Dundrum, and 5.09 inches at Bray, causing disastrous floods in various parts of that country. At Little Bray, the inmates of the lower-lying houses had to be rescued by boats. Sharp thunderstorms occurred in London and other parts on Sunday, Monday, and Tuesday, causing much damage to property. At Leigh, in the neighbourhood of

a

man

Tonbridge, the trunk of an oak tree was torn in half, and who was seeking shelter under it was killed. During this period, rainfall has been considerable in all parts of the British Islands; in the twenty-four hours ending at 8h. a.m. on Tuesday, August 29, the amounts at Oxford and Yarmouth exceeded an inch, and an inch and a half was measured in the neighbourhood of London.

THE programme of the Iron and Steel Institute for the meeting to be held at Sheffield on September 26-29 includes the following list of papers :-Wear of steel rails on bridges: T. Andrews, F.R.S.; metallurgical department of Sheffield University: Prof. J. O. Arnold; thermal transformation of carbon steels: Prof. J. O. Arnold and A. McWilliam; nature of troostite: Dr. Carl Benedicks; occurrence of copper, cobalt, and nickel in American pigirons: Prof. E. D. Campbell; transformations of nickel steels: L. Dumas; on steel for motor-car construction, and on vanadium steels: L. Guillet; presence of greenishcoloured markings in the fractured surface of test pieces : A. W. Captain H. G. Howorth; over-heated steel: Richards and J. E. Stead, F.R.S.; segregation in steel ingots B. Talbot; manipulator for steel bars: D. Upton ; influence of carbon on nickel and iron: G. B. Waterhouse.

ATTENTION is directed by the Engineering and Mining Journal of New York to a new development in mining which has not been generally noticed, namely, the working of alluvial tin deposits by dredging in the same of gold-bearing manner as that followed in the case gravel. In New South Wales the dredging for tin ore has become an established practice. In 1904 there were seven dredges in operation, which obtained 319 tons of tin ore, valued at 26,000l. The successful development of this practice in New South Wales suggests that it might possibly be applied with advantage in the Straits Settlements and elsewhere.

In

IN a paper read before the Geological Society of America, Mr. George P. Merrill described a large block of massive serpentine traversed by veins of so-called asbestos from Thetford, Canada, now exhibited at the United States National Museum at Washington. cidentally discussing the origin of the veins, he suggested that the vein cavities are shrinkage cracks filled by a process of crystallisation extending inward from either wall, and compared the veins to the shrinkage cracks formed in septarian nodules of clay ironstone, and their filling with fibrous material to the crystallisation of fibrous gypsum in limestone.

AN ordinance relating to lead works has just been issued by the German Imperial Chancellor. The employment of women and lads in dust chambers and flues and in the transport of the dust is prohibited. The workmen employed at the furnaces may not work more than eight hours a day. The same rule applies to the workmen working inside cold furnaces or engaged in cleaning dust chambers and flues containing wet dust. Workmen engaged in cleaning dust chambers and flues containing dry dust are not permitted to work more than four hours a day inside such chambers and flues, and not more than eight hours a day in all. Food must not be taken to the working places. Working-suits, respirators, and gloves must be worn. Smoking cigars and cigarettes during work is forbidden. The rules will come into force on January 1, 1906.

THE most important paper in the June issue of the Proceedings of the Philadelphia Academy is perhaps one