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FIG. 14.

the confusion it had created. In Fig. 14 the glass plate is seen edgeways just after the bullet has struck it. It is clear at once that the splash of glass dust backwards is already four or five times as rapid as the motion of the bullet forwards. A new air wave is just beginning to be created in front of the glass-coated head of the bullet and two highly-inclined waves, one on either side of the glass, reaching about three-quarters of the way to the edge, have sprung into existence. These are more clearly seen in the next figure; meanwhile it may be well to point out that the fragments of paper which are following the bullets have in this case-as the card was much nearer to the glass plate than in those previously takensome of them lost so much of their velocity and have in consequence lagged behind in a still higher proportion than the others, that they are travelling at less than 1100 feet a second; the more backward ones carry in consequence no air waves and there is no means of telling from the photograph that they are moving at all. In Fig. 15 the bullet has struggled about half way through the plate. The waves on either side of the plate have now reached the edge and are on their way back towards the centre again. They are caused in this way. When the bullet strikes the plate the violent shock produces a ripple or tremor in the glass which travels away radially in all directions, leaving the glass quiet behind. The rate at which this ripple travels may be found from the angle which these new air waves make with the plate, for taking any point on the plate and measuring up to the point where the air wave meets the plate and also the distance in air to the nearest point of the inclined air wave, we get two distances, the ratio of which is the ratio of the velocity of the disturbance in the glass to the velocity of sound in air. But much more

up of a series of dark and light lines at a very sligh

than this is shown. An examination of the negatives or of inclination to the air wave itself, so that as we tre

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moved inwards to rarefy it so that the wave length of the ripple may thus be found, and finally it is seen that where the waves are waves of compression on one side of the plate they are waves to rarefaction on the other, indicating that it was a transverse and not a mere longitudinal disturbance that ran along the plate from the centre outwards and back again after reflection from the edge. In addition to this the fact that the reflected wave is still on its inward course proves that up to this time the plate is whole, as a wave cannot be propagated in a broken plate. Fig. 16 illustrates the state of affairs when the bullet has travelled about five inches beyond the plate. It has not yet emerged from the cloud of glass dust. The new head wave is very conspicuous. In the original negative, about half way between the bullet and the plate, the inclined waves due to the tremor in the glass plate may be detected, but they are too delicate to be reproduced by the printing process. They supply the information as to how long the plate remained whole or rather if the bullet had been caught a little sooner before these faint waves had lost so much of their distinctness they would supply this information with great exactness. Meanwhile the figure shows that the plate is now broken up completely. It is true it is still standing, and the stern air wave is seen reflected from the upper part of it, but this is because the different parts have not yet had time to get away; their grinding edges, however, have cast out from the surface little particles, and these are seen over the whole extent of the plate. After about fifteen inches the bullet is quite clear of the cloud of dust (Fig. 17); one piece only of the glass, no doubt the piece that was immediately struck, has been punched out and is travelling along above the bullet at a speed practically equal to its own. I am also able to show the plate itself in this and a still later stage, when at last the separate pieces have begun to be visibly moved out of their position and in some cases slightly turned round.

I have merely given this evening an account of a few glass first moved outwards to compress the air or first experiments which in themselves perhaps are of little

interest, but they at any rate show the capability of this method for the examination of subjects which would in the ordinary way be considered beyond the reach of experiment. It is hardly necessary to say that the examples given by no means reach the limit of what may be done, I have examined the explosions produced by fifteen-grain fulminate of mercury detonators and of heaps of iodide of nitrogen, a material which is rather unmanageable, as if a fly even walks over it it violently explodes. In these cases the explosive flash was used to make the B gap of Fig. 4 conducting, for which it answered perfectly. One might in the same way examine the form of the outrush of powder gases past the bullet, and so find at once their velocity with respect to the velocity of the bullet, and I see no great difficulty in tracing, if this should be desired, the whole course of a single bullet for perhaps as much as 100 yards by means of photographs taken every few inches on its way. Though it may not be evident that these or similar experiments are of any practical importance, there can be no doubt that information may be readily obtained by the aid of the spark photograph, as in fact has been shown by Prof. Mach, Lord Rayleigh, Mr. F. J. Smith, and others, which without its aid can only be surmised, and that if, as in other subjects, the first wish of the experimentalist is to see what he is doing, then in these cases surely, where in general people would not think of attempting to look with their natural eyes, it may be worth while to take advantage of this electrophotographic eye.

I wish in conclusion to express my obligation to the gentlemen to whom I have already referred, to Messrs. Chapman and Colebrook for their assistance, and to Messrs. Moore and Grey for having supplied me with weapons and ammunition.

MICRO-ORGANISMS AND THEIR

INVESTIGATION.

As the field of bacteriological investigation becomes

extended, we have of necessity constant additions to the various methods rendering possible the pursuit of researches in these novel directions. We have only to look at the first edition of Hueppe's "Methoden der Bakterien-Forschung," published in 1885, consisting of 174 pages, and compare it with the bulky volume of 488 pages which forms the fifth edition, to see at a glance

the advance which has been made in the matter of methods alone. In Flügge's "Die Mikro-organismen " we have another type of book, dealing exclusively with micro-organisms themselves, and the information which has been gathered together concerning them, whilst all details of bacteriological practice are purposely omitted. Dr. Günther has attempted a welding together of these two types of book, special attention being given to microscopical technique with which his name is indeed more particularly associated.

The first part is devoted to a survey of our knowledge concerning bacteria in general, commencing with the earliest observations of Leeuwenhoek in 1683. In this review we find an account of their morphology, the principles upon which their classification is attempted, &c., together with a detailed account of the most recent methods for their cultivation and subsequent study, including careful directions for the use of the microscope, and a most elaborate description of the available means for staining bacteria.

The second part is confined to a consideration of the best-known pathogenic and non-pathogenic microorganisms.

There could not be a more admirable account of the 1 "Einführung in das Studium der Bakteriologie." By Dr. Carl Günther. Second Edition. (Leipzig: Georg Thieme.)

Technique Bactériologique." By Dr. R. Wurtz. Encyclopédie Scientifique des Aide-Mémoire. (Paris: Gauthier-Villars et fils, 1892.)

numerous manipulations involved in bacteriologica vestigations; all the minutia are described with utmost care, and what is usually left for the stude learn in "profiting by his experience" is here care anticipated, and if he tumbles into any pitfalls, it at because he has been without warning.

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With such a big task as Dr. Günther has set hi it is not surprising to find some parts less amply de with than they would seem to deserve. Thus we but a very meagre supply of culture media given, is no mention of the preparation of milk, or of special solutions employed by Pasteur, Naegeli others, neither is there any account of Kühne's jelly, which since our knowledge of the fact that ce organisms will only flourish in media devoid of organic matter, ought surely to have been included. On the other hand a minute description is given a gelatine-plate, dish and tube cultures, as well as most modern methods for the anaerobic cultivation bacteria, &c. In connection with the abstractic certain colonies from gelatine-plates, mention may made of a piece of apparatus (the description of w was only published after Dr. Günther's book appeust originally devised by Fodor, and called "Baktere. Fischer," which has been, under the name of "E terienharpune," more recently modified and cons ably cheapened by Unna. Every one has experiens the difficulty of fishing out a particular colony crowded plate, how it is almost impossible to l through the microscope and fix upon the centre tele abstracted, and at the same time keep the needle ste and ensure touching only the one colony which is t quired. By using the above contrivance, which c attached to the microscope, the fishing out of g centres is greatly facilitated.

The examination of air for micro-organisms is very slightly touched upon, as is also the bacteriolc investigation of water. It is a little rash to assert the

"pathogenic micro-organisms can live for a long tim

sterilised water," considering that it has been shown destroy them. Again, no mention is made of Hanssome cases that their immersion only is sufficient special methods for the examination of particular water although they are opposed to the Koch school ought not to preclude a reference to what has 29 proved by a large number of investigations to be some cases, of great practical utility.

The second part opens with a short introduction. described, and an account given of the rigid proof which the nature of pathogenic organisms in gener is required before a particular organism may be s be the cause of a particular disease. Protective inoc koff's brilliant theories of phagocytosis summary tion and immunity are briefly referred to, and Mets missed, and declared incapable of standing the te the "careful experimental criticism to which they been submitted by Flügge, Baumgarten, and the auth

own pupils."

As many as twenty-seven different varieties of m organisms are described in the section on the mas portant pathogenic bacteria. Amongst these we fir micro-organisms associated with anthrax, tuberca and chicken-cholera, more especially dealt with, diphtheria, cholera, pneumonia, tetanus, typhoid ceedingly useful and comprehensive summary be given in each case of what is known concerning together with numerous references to original pa disciple of Koch's will at once be admitted, when we published on the subject. the terms in which he speaks of the Tuberculinum k "Eine neue Aera begann nicht allein für die I = culoselehre, sondern für die gesammte Medicin, grossen Entdeckung Koch's der Heilung der 12 culose."

That Dr. Günther is an ar

Amongst the non-pathogenic forms we find an account of the Micrococcus agilis, which was found by Ali-Cohen n drinking water. This was not the first motile coccus ound, as is stated by Günther, for previous to this, Mendoza isolated and described a motile form which he called Micrococcus tetragenus mobilis ventriculi. The Micrococcus agilis was the second variety found; whilst later, in 1890, Loeffler also discovered and described a motile coccus. It is surprising, therefore, to read that Ali-Cohen's variety is the only motile micrococcus known. The list has further been quite recently (1892) enriched by the discovery by Maurea of a motile sarcina, which he has designated Sarcina mobilis.

A fine set of seventy-six photographs, mostly taken from original preparations, together with a very exhaustive index, completes the volume. Amongst the photographic figures the series of twelve representing anthrax in every stage of development from the individual bacteria to their appearance as colonies on gelatine-plates, and growing in test-tube cultivations, are particularly beautiful; the surface colonies photographed after fortyeight hours' growth are especially characteristic and successful.

In the handy little volume "Technique Bactériologique," of Dr. Wurtz, chief of the laboratory for experimental pathology in the Faculty of Medicine in Paris, we have an entirely different stamp of book. We read in his preface: "On ne trouvera, dans ce précis de Technique bactériologique, ni l'historique, ni l'exposé detaillé des nombreuses méthodes techniques qui ont été préconisées jusqu'à ce jour en microbiologie. Conformément au programme tracé par la Direction de P'Encyclopédie Scientifique des Aide-Mémoire, nous nous sommes efforcés d'éxposer, aussi clairement que possible, les notions qu'un débutant doit posséder à fond avant d'aborder l'étude proprement dite des microbes."

Proceeding on these lines Dr. Wurtz gives us a very clear and precise account of all the various important stages passed through in bacteriological manipulations, commencing with a chapter on the principles of sterilisation.

But a novel feature in this volume is the description of the various methods of conducting experiments on animals for bacteriological purposes. This is carefully recorded and supplemented by woodcuts, and would appear to be a most useful addition, for although the possibilities of carrying out such experiments in this country are very limited, yet in those cases where they are permitted such an accurate description of the methods to be adopted should prove very helpful, more especially as in very few of the German and English bacteriological text-books is any account to be found for the information of those desiring to undertake such investigations. A chapter is also devoted to the enumeration of the substances, in as far as they have been investigated, which are elaborated by micro-organisms and a description of the most convenient methods for their successful extraction.

The crisp and concise language which characterises the book, together with the judgment displayed in its compilation, show that the author possesses, not only a full grasp of his subject, but is also highly skilled in the art of communicating it to others.

GRACE C. FRANKLAND.

THE ORDNANCE SURVEY.

A DEPARTMENTAL committee was appointed by

the Board of Agriculture in April, 1892, to inquire into the condition of the Ordnance Survey. The committee consisted of Sir John E. Dorington, M.P. (chairman), Sir Archibald Geikie, F.R.S., Mr. Henry W. Primrose, Mr. William Mather, M.P., Mr. H. J. Roby, M.P., and Mr. Charles Fortescue Brickdale, with Major

Duncan A. Johnston, R. E., as secretary. The matters referred to then were:

1. What steps should be taken to expedite the completion and publication of the new or revised one-inch map (with or without hill-shading) of the British Isles? 2. What permanent arrangements should be made for the continuous revision and speedy publication of the maps-1 in 500 (towns), 25 in., 6 in., and I in. scales? 3. Whether the maps as at present issued satisfy the reasonable requirements of the public in regard to the style of execution, form, information conveyed, and price, and whether any improvement can be made in the catalogue and indexes?

After the appointment of the committee Mr. T. Ellis, M.P., asked in the House of Commons a question which showed that there was dissatisfaction with regard to the inaccuracy and incompleteness of the names of places in the map of Wales; and this question was also referred to the committee.

The report of the committee has just been issued, and includes the following recommendations :

:

1. That the I in. map be produced in the following forms :(a) An engraved outline map, with contours in black. (b) A black engraved map, with hill-shading either in black or in colour.

(c) A coloured map on thin paper, adapted to military purposes, but also on sale to the public.

(d) A cheap map by transfer to zinc or stone.

2. That the character of the roads on the 1 in. map be shown in four classes with distinct characteristics.

3. That parish boundaries be omitted from the I in. map. 4. That the contours of the sea bottom round the coast line and the depths of inland waters be shown.

heliogravure, and that, if results not inferior to 5. That experiments be made in the practical application of an Austrian specimen map which we have seen he produced, that process be substituted for the existing method of engraving hills, and for so much of the country as is then uncompleted in its hill engraving.

6. That special arrangements be made to revise the I in. map within the next four years independently of the maps on the larger scales, and that subsequently this map be constantly revised within periods of fifteen years.

7. That the cadastral maps be revised and brought up to date in the next ten years, and that subsequently they be kept revised within periods of fifteen years.

8. That the publication of these revised maps be carried out by contract, if necessary.

9. That detail, such as single trees, footpaths in gardens, &c., be omitted.

10. That the skeleton and coloured forms of the 25 in. and town maps be abandoned, and the uses of both be combined in one edition having the houses cross-hatched.

II. That the reference numbers to parcels of land on the 25 344 in. plans be abandoned on revision.

12. That to a limited extent additional contour lines be added to the 6 in. map.

13. That on the 6 in. map the contours be always in black. 14. That certain of the engraved plates of the 6 in. map which are not now filled up beyond the county boundary be as soon as possible filled up to the margin of the plate with the detail of the adjoining county.

15. That the cost of the engraved sheets of the 6 in. map and that of the quarter-sheets of the photo-zincographed 6 in. map be equalised by a change of their respective selling prices. 16. That the Welsh names be gone over and corrected before the first revision of that map.

17. That the cadastral maps on the town scales be no longer entirely made or revised at the cost of the State, but that the town authorities be required by statute to maintain these maps.

18. That around towns and in tourist districts the existing sheets of the Ordnance Survey on the 6 in. and I in. scales be united so as to form special maps of such districts, and that cartography that may be thought desirable, as these maps are advantage be taken of these maps to introduce any novelties in Kingdom. not required to be joined to the general maps of the United

19. That certain authorities be placed under statutable

obligation to supply information to the Ordnance Survey Department in order to enable current revision to be better carried on.

20. That in future the term "revision" should be confined to

the bringing up to date on its existing scale of a map already published, and that the term "resurvey" be applied to the operations necessary for the production of maps on a scale larger than that on which they were originally published.

21. That the Ordnance Survey Department be allowed to control its own supply of paper and printing material.

22. That the map on the scale of four miles to an inch be revised as soon as the I in. map is out of hand, and be completed with hill-shading.

23. That great freedom be allowed to private publishers desirous of bringing out other classes of maps than those specially published by the Survey Department, and that trans. fers of the maps on the I in. and smaller scales be supplied to publishers at cost price, a small sum being paid as an acknowledgment, and that all other reproduction of Ordnance Survey maps be prohibited.

24. That certain recommendations as to indices and catalogue be carried out.

25. That a book or pamphlet of information as to the Ordnance Survey be published, general in its main features and special for each county, containing the county indices or diagrams (on a reduced scale) and the information formerly contained in the parish area books, and also the table of parish areas now printed on the index of the 6 in. map, which table should in future be omitted from that map, and that copies of the small indices in this pamphlet be freely distributed for public information.

NOTES.

OWING to the large demand for tickets for the Croonian Lecture, which is to be delivered by Prof. Virchow before the Royal Society and their friends next Thursday, it has been decided to hold the meeting in the theatre of the London University, which has been lent for the occasion by the kind permission of the Senate.

THE public dinner which is to be given in honour of Prof. Virchow will be held on March 16, after the delivery of the Croonian lecture, at the Hôtel Métropole. Lord Kelvin will preside, and will be supported by the Presidents of the Royal Colleges of Physicians and Surgeons as vice-chairmen.

AT the Nottingham meeting of the British Association, over which Prof. Burdon Sanderson will preside, Lord Salisbury will be nominated president of the Association for the Oxford meeting in 1894. The following gentlemen have consented to act as presidents of sections at Nottingham :-Section A, Mathematical and Physical Science, Prof. Clifton, F.R.S.; Section B, Chemistry and Mineralogy, Prof. J. Emerson Reynolds, F.R.S.; Section C, Geology, Mr. J. J. H. Teall, F.R.S.; Section D, Biology, the Rev. Canon Tristram, F. R. S.; Section E, Geography, Mr. Henry Seebohm, Sec. R.G.S.; Section F, Economic Science and Statistics, Prof. J. S. Nicholson; Section G, Mechanical Science, Mr. Jeremiah Head; and Section H, Anthropology, Dr. Robert Munro.

AT the ordinary meeting of the Royal Meteorological Society, to be held at 25, Great George Street, Westminster, on Wednesday, the 15th instant, at 7 p.m., a lecture will be given by Mr. Shelford Bidwell, F. R. S., on some meteorological problems, which will be illustrated by experiments.

DR. R. THORNE THORNE, Medical Officer of the Local Government Board, and Mr. H. Farnall, of the Foreign Office, have gone to Dresden, the former as British delegate to the International Sanitary Conference in that city, the latter as assistant delegate.

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IN reply to a question put by Sir Henry Roscoe in the How of Commons on Friday last with regard to the proposed buildings for the Royal College of Science, Mr. Shaw Leferri

said:-"The accommodation at the Royal College of Science !. is now undoubtedly inadequate, and in my opinion new bui ings must be undertaken at some early opportunity. B plans were drawn up in 1891 by the professors of the Rry. College of Science, showing a suggested appropriation of e land on the south side of the Imperial Institute Road, for purposes both of the Royal College of Science and of the Scinc Museum, and these plans were submitted to the Office of Work but that Department pointed out that it would be premature. them to consider the plans until the Science and Art Depar ment had obtained the sanction of the Treasury to an org tion of their teaching and exhibition establishments on the contemplated in the plans. I understand that the Science Art Department are now in communication with the Trea in this sense." Sir H. Roscoe having asked when the rep from the Science and Art Department would be issued, } Shaw Lefevre said it was not in the nature of a report that c be issued to Parliament, but he should be happy to show r the hon. member.

LAST week a meeting, convened by the Duke of Weste as president of the Royal Agricultural Society, was held £ Hanover Square, to consider the best means of commemorati the completion of the first half-century of the agricultural expe ments which have been continuously carried on by Sir! Lawes at Rothamsted since the year 1843. The Prince Wales presided. On taking the chair his Royal High stated the objects of the meeting. The Rothamsted experie had from the commencement been entirely disconnected with external organisation and had been maintained at the sole of Sir John Lawes. For the continuance of the investiga after his death Sir John had recently made the munita endowment of £100,000, besides the famous laboratory certain areas of land, and had nominated some of the most

tinguished men of science of the day to administer the trust. view of all these facts, and the great national importance :f Rothamsted experiments, it was only fitting that some pi recognition should be made of the invaluable services rende to agriculture by Sir John Lawes and his distinguished colleag Dr. Gilbert. The Duke of Westminster said they all be that Sir John might live for many years to continue to carry these experiments for the benefit of agriculture. He had g pleasure in proposing the following resolution :-"That, ba regard to the great national importance of the series of expe

ments which have been carried on at Rothamsted during last fifty years, it is desirable that some public recognition sh be made of the invaluable services thus rendered to agric by Sir John Lawes, and also by Dr. Gilbert, who has ter associated with the experiments during the whole period. ?!. with this object, subscriptions, to be limited to two guiners invited from all interested in agriculture, whether scienti practical." Mr. Thiselton-Dyer, F.R. S., seconded the re tion-not as an agriculturist, but as one officially and all deeply interested in everything that was concerned with bez science. The extraordinary merit of the work carried a Rothamsted lay in the fact that those experiments had best tinuously carried on under uniform conditions for soi

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