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selves for a belter understanding of the alloys of metals which come within the scope of every-day experience.

From the engineer's point of view, as the report state*, the most interesting information which the pyrometer has yet afforded is conneeed with the measurement of the internal stresses in iron and steel. The molecular change which takes place in steel must be of vital importance when the metal is subjected at high temperature to mechanical operations such as rolling or forging. "Do the molecular changes in the iron take place at one moment throughout the mass of metal? that is, is the rate of cooling approximate throughout the mass, or does the external portion of the ingot cool so much more rapidly than the centre as to allow the molecular changes in the iron, and the relation between the carbon and the iron, to become completed near the surface long before they take place in the interior of the mass?" The pyrometer used allows some insight to be gained into this hitherto unassailable problem. A small ingot of mild steel had two holes drilled into it, one near the circumference, and the other at the centre. The ingot was heated, and a tbermo-junction was inserted in each hole. In this way curves of temperature were obtained simultaneously. With the mild steel the evidence as to molecular change was but slight. Another ingot of steel, containing 0799 per cent, of carbon, 0084 per cent, of silicon, and 0*412 per cent, of manganese, was tried in the same way. The initial temperature at the centre was 1160° C. The curve showed the molecular change at 880° C, and the carbon change at 696° C. At the circumference the carbon change took place no less than four minutes earlier than at the centre, and at the lower temperature of 665° C. This is a most important point, as the rate of cooling, as Osmond has pointed out, has a measurable effect upon the temperatures at which molecular change occurs. The great internal strain which must be set up is evident when it is borne in mind that the carbon change is accompanied by a considerable alteration of volume. It is pointed out in the report that "there can be but little question that such experiments well deserve careful attention, and, in the hands of competent observers, should be fruitful of results."

On the conclusion of the reading of the paper, the President called for a discussion, when Dr. Anderson was the first to rise. He spoke in terms of warm praise as to the value of the work done by Prof. Roberts-Austen. As an instance, he mentioned that the method described in the report, by which the temperatures of an ingot could be obtained simultaneously at the centre and the circumference, would be of the greatest use in dealing with the large pieces of steel used for gun-hoops; and he expected great help from this in the work at the Royal Arsenal.

Mr. R. Hadfield, of Sheffield, followed. He gave a summary of the effect of the most prominent alloys of iron. This table will form a useful appendix to the report when published in the Transactions of the Institution.

Prof. Howe, of Boston, gave an instance in which the Le Chatelier pyrometer had been turned to good practical account. This was in the Rodman system of gun-casting. In that process it was most desirable to know the varying temperatures of different parts of the cast, but naturally this had been hitherto impossible. By inserting a thermo couple in the mould it was possible to get this information at all times. He thought the Le Chatelier pyrometer the greatest boon that metallurgists had received for very many years.

The next speaker was Prof. Arnold, of Sheffield, who made a certainly vigorous speech. We think, however, that he was rather carried away by his enthusiasm. To say that the work done by the author of the report was "not worth a rush," is rather straining the prerogative of rhetoric; and we failed to see, when Prof. Arnold descended to facts, that he justified the florid language of his exordium. Prof. Roberts-Austen, in his reply, gave an example of forbearance and good temper which it would be well if men of science could often follow. It was satisfactory to notice that the feeling of the meeting was by no means in accordance with Prof. Arnold.

Mr. Stromeyer added to the work done a useful table in which were collated the opinions of various authorities on the effect of alloys upon iron. The table was not read, but will be published in the Proceedings. Such work as this is very acceptable. It involves a great deal of labour and brings but small return in the way of praise and glory, which of course are two things to *hich a true follower of science is profoundly indifferent.

Mr. Stead, of Middlesborough, protested against Prof. Arnold's remarks, and spoke of the value of the author's work. The testimony of Mr. Stead is valuable, as he combines the position of a practical investigator, working for commercial ends, and a man of science.

The meeting broke up after passing the usual votes of thanks.

UNIVERSITY AND EDUCATIONAL
INTELLIGENCE.

Oxford.—The Junior Scientific Club held their first meeting this term in the Physiological Laboratory at the Museum, under the presidency of Mr. R. S. Gunther, of Magdalen.

Mr. W. Pullinger, of Balliol, read a paper on volatile platinum compounds, and exhibited prepared specimens.

Mr. A. F. S. Kent, of Magdalen, indicated improvements in the manipulation of photo-micrography whereby the eflVct of tremcrs was excluded, and passed through the lantern some very excellent slides which he had taken from negatives obtained by his new method.

Mr. G. E. C. Pritchard, of Hertford, exhibited specimens of Bacteria, and described the method whereby they had been obtained and prepared for microscopic exhibition.

Dr. Collier read a paper of a very interesting character on the physiology of muscular exercise with special reference to training, in the course of which he traversed some statements recently made by Sir Morell Mackenzie, to the effect that fatigue was due to the cessation of blood flowing to the muscles. Dr. Collier would rather attribute fatigue to the development of waste-products in the muscle, formed too rapidly for the blood to remove them, and quoted experiments carried out on frogs which seemed to support this view.

Cambridge.—The Agricultural Education Syndicate, in view of a grant of ^400 a year from the Cambridgeshire County Council, recommend that a lecturer in agricultural science, who shall also be director of agricultural studies, should be appointed at a stipend of ,£500. They also propose that a second lecturer be appointed at a stipend of £$co. These two lecturers would take between them the subjects of agricultural botany and agricultural chemistry.

The degree of M.A. honoris causa) has been conferred on the distinguished entomologist Mr. D. Sharp, F.R.S., Curator in Zoology at the University Museums.

Dr. Sir A. Geikie and Dr. T. G. Bonney have been appointed adjudicators of the Sedgwick Prize of 1895.

At St. John's College, on November 2, the following were elected to the vacant Fellowships: William McFadden Orr, B.A., Senior Wrangler, 1888; Edward Ernest Sikes, B.A., First Class (Division 1), Classical Tripos, 1889, Newton Student in Archaeology; Percival Horton-Smith, B. A., First Class Natural Sciences Tripos, 1889-90 (distinguished in physiology), late Hutchinson Student in Physiology.

SOCIETIES AND ACADEMIES. Paris. Academy of Sciences, October 26.—M. Duchartre in the chair.—On the theory of Hertz-oscillations, by M. H. Poincare. —On a new mineral—boleile. by MM. Mallard and E. Cumenge. The new mineral occurs with copper in volcanic luff and conglomerate found near Santa Rosalia, Lower California. It crystallizes in the cubic system, and its composition is represented by the expression PbClj + CuO. H?6 + 3AgCl. Its density is a li!tie greater than that of calcite; cleavage easy parallel to the faces of cube, much less easy parallel to faces of octahedrons. Approximate index of refraction, 2'07.—Vasomotor action of bacteria, by M. Ch. Bouchard.—Contribution to the botanical history of the truffle (fourth note): Kama of Bagdad (Terftzia Hafizi and Terfezia metaxasi) and of Smyrna (Terfezia Leonis), by M. Ad. Chatin.—On a storm observed at the Canary Islands. This is an extract from a memoir by M. de la Monneraye.—On the original causes of cyclones, and on their precursory signs: extract from a memoir by M. Le Goarant de Tromelin.—On the theory of the voltaic pile, by M. P. Duhem.—Experimental researches on a category of capillary phenomena, with an application to the analysis of alcoholic liquids and others, by M. l'.mile Gossan.—On bromo

stannates, by M. I.eteur. The auihor has prepared the following bromoslannates, the general method consisting in mixing concentrated solutions of the two bromides, and evaporating the mixture in a vacuun or dry air: SnBr4NH4Br, SnBr4NaBr + 6H..O, MgBr2 . Snlir4 + toHsO.—On a new crystalline ferric oxychloride, by M. G. Rousseau. Concentrated solutions containing more than 80 per cent, of FejCI,,, if kept for some time at a temperature between 160' and 220° C, give rise to crystalline ferric oxychloride, 2Fe203. Fe2Cl2. 3H.O. The author has studied the decomposition of solutions of ferric chloride at temperatures higher than 220°. Between 225' and 280° anhydrous oxychloride (2Fe203 Fe2Cl6) was obtained. At temperatures between 300° and 340° a new oxychloride was formed.'having the composition 3Ke303Fe2.C]|j.—On the estimation of thallium, by M. H. Baubigny.—On the solution of bismuth chloride in saturated solutions of sodium chloride, and on the basic salicylate of bismuth, by M. H. Causse.—On a characteristic difference between the alcoholic radicles substituted in place of carbon and nitrogen, by M. C. Matignon. From a thermo-chemical investigation the author finds that the substitution of an alcoholic radicle for nitrogen increases the heat of combustion more than the substitution of the same radicle for carbon.—Action of benzoic acid on essence of turpentine, by MM. G. Bouchardat and J. Lafont.—On the formation of quaternary iodides of ammonium by the action of trimethylamine, in concentrated aqueous solutions, or the hydriodic ethers of several primary and one secondary alcohol, by MM. H. and A. Malbot. —On a new albuminoid substance in the blood serum of man, by M. C. Chabrie.—The soluble substances of the pyocyanic bacillus producing fever, by M. A. Charrin.—Experimental progressive muscular atrophy, by M. Roger.—Some anatomical characteristics of Hyperoedon rostratus, by M. E. L. Bouvier.— Apropos the chromatophores of Cephalopods, by M. Raphael Blanchard.—Physiology of the nerve which enables us to localize sounds, by M. Pierre Bonnier.—On a method for destroying insects injurious to the beetroot and cereals, by M. Decaux.

DIARY OF SOCIETIES.

London.
THURSDAY, November 5.

Linnhan Society, at 8.—A Theory of Heredity based on Force instead of
Matter: Rev. Prof. Henslow,

Chemical Society, at 8.—The Disociation of Liquid Nitrogen Peroxide: I. Tudor Cundall.—The Magnetic R nation of the Ammonium and Sodium Salts of Fatty Acids: Dr. Perkin, F.R.S.— The Vapour-Pressures and Molecular Volumes of Acetic Acid and of Carbon and Tin Tetrachlorides: Prof. S. Young.—The Ortho- and Para-nitro Derivatives of Orthotoluidine: A. G. Green and T. A- Lawson.—Researches on the Gums of ArabinGroup, Partll.: C. O'Sullivan, F.R.S.

Camera Club, at 8.30.—The Action of Light and Heat upon the Haloid Silver Salts: Dr. J. J. Acworih.

FRIDAY, November 6.
Physical Society, at 5.—On Corresponding Temperatures, Pressures, and

Volumes: Prof. Sydney Young.
Geologists* Association, at 8.—Conversazione.

SATURDAY, November 7.
Essex Field Club, at 7.—Notes concerning the Distribution of Mollusca
in the Thames Estuary: A. J. Jenkins.—Sonic Remarks upon the
Aquatic Plants and Algae of the Thames Marshes: A. J. Jenkins.—
On the Occurrence of Westleton Beds in part of North-Western Essex:
J. French.

SUNDAY, November 8 Sunday Lecture Society, at 4 —The Personal Life of Shakespeare: \V. E. Church.

MONDAY, November ). Camera Club, at 8.30.—Lenses, II. : Lyonel Clark. TUESDAY, November 10. Mineralogical Society, at 8.—Anniversary Meeting. Institution Of Civil Engineers, at 8.—President's Address: George

Berkley.—Presentation of Medals, Premiums, and Prizes. Photographic Society, at 8.

WEDNESDAY, November Ii. Geological Society, at 8.—On Dacrytherium ovinum from the Isle of Wight and Quercy: R. Lydekker.—Supplementary Remarks on Glen Roy: Thos. F. Jamieson.

THURSDA Y, November i2.

Mathematical Society, at 8.—On the Classification of Binodal Quartic

Curves: H. M. JetTery, F.R.S.—On Selective and Metallic Reflection:

A. B. Basset. F.R.S.—On a Class of Automorphic Functions: Prof. W.

Burnside.—The Contacts of Systems of Circles: A. Larmor.—Note on the

Identity 4 (_r/ - I)/(j- - 1) = Y-±/Z-: Prof. G. B. Mathews—Note on Finding the G Points of a given Circle with respect to a given Triangle of Ktfercncc : J. Griffiths.

Institution Op Electrical Engineers, at 8.—Description of the Standard Volt and Ampere Meter used at the Ferry Works, Thames Ditton: Captain H. R. Sankey ('ate R.E.)and F. V. Andersen.

Camera Club, at 8.30.—A New Method of Photography by Artificia Light: E.J. Humphery.

FRIDAY, November 13.
Royal Astronomical Society, at 8.

Institution or Civil Enginrrhs, at ?• 30.—Description of the Works on
the Barking and Pitsea Extension Railway : Henry E, Stilgoe.—Rail Pile
Bridges in Ceylon: Harry Bucknall.
Camera Club, at S.—Retouching : Redmond Barrett.
SATURDAY, November 14.
Royal Botanic Sojikty, at 3.45.

BOOKS, PAMPHLETS, and SERIALS RECEIVED.

Natural Theology : Sir G. G. Stokes (Black).—Elementary Trigonometry t J. M. Dyer and Rev. R. H. Whitcombe (Bell).—Fundamental Problems; Dr. P Cams, 2nd edition (Chicago). — L' Amateur d'Oiseaux de Vollere: HMoreau (Paris. Baillicre).—Les Coquilles Marines: A. Locard (Paris, Bailli&re).—Colour-Blindness and Colour-Perception: Dr. F. W. EdridgeGreen (Paul).—Handleiding tot de Kennis der Flora van Nederlandsch Indie: Dr. J G. Boerlage, Tweede Deel, Eerste Stuk (Leiden, Brill).—Star Groups: J. E. Gore (Lock wood).—Elementary Thermodynamics: J. Parker (Cambridge University Press).—Report on the Meteorology of India in 1889: J. Eliot (Calcutta).—Copernic et la De'couverte du Systtme du Monde: C. Flammarion (Paris, Marpon and Flammarion).— Moral Teachings of Science: A. B. Buckley (Stanford). —Further Reliques of Constance Naden: edited by G. M. McCrie (Bickers).—The Wire and the Wave: J. Munro (R.T.S.). —Ytterligare r>m Gadolinit-Jordens Molekylarvigi: A. E. Nordenskiold (Stockholm).—Notes on the Recent Geometry of the Triangle: J. Griffiths (Simpkin).—Journal of the Royal Microscopical Society, October (Williams and Norgate).—Illustrations of the Flora of Japan. vo'. i. No*. 7- R. g fTokyo).

CONTENTS. Page Electricity and Magnetism. By Prof. A. Gray ... t Biology of Seaside Plants. By W. Botting Hemsley, F.R.S 3

Ricardo's "Political Economy." By W. E. J. . . . 4 Our Book Shelf:—

Schnauss: '' Photographic Pastimes : a Hand-book for

Amateurs" 5

"On Surrey Hills" 5

Munro: "Heroes of the Telegraph" 5

Letters to the Editor:—

The Koh-i-Nur. (Illustrated.)—Prof. N. Story

Maskelyne, F.R.S 5

A Rare Phenomenon.—Dr. M. A. Veeder; Prof.

J. G. MacGregor; R. N. Hudspeth 7

Apparent Size of Objects near the Horizon.—T. W.

Backhouse 7

Proper Motions of the Stars.—W. H. S. Monck . . 8

California Foxes. —Prof. Edward S. Holden ... 8

A Plague of Small Frogs. —R. Haig Thomas ... 8 Botany of the Emin Relief Expedition. By W. T. Thiselton Dyer, C.M.G., F.R.S.; Major I. A. M.

Jephson 8

Town Fogs and their Effects. (Illustrated.) By Dr.

W.J. Russell, F.R.S.; W.Watson 10

The Anatomy of the Dog. (Illustrated.) 16

Notes 18

Our Astronomical Column:

The Telluric Spectrum 21

Tempel-Swift's Periodic Comet 21

Catalogue of Rutherfurd's Photographs 21

The Institution of Mechanical Engineers 22

University and Educational Intelligence ... 23

Societies and Academies .... 23

Diary of Societies 24

Books, Pamphlets, and Serials Received .... 24

THURSDAY, NOVEMBER 12, 1891.

THE HYGIENE OF WATER-SUPPLY.

An Elementary Hand-book on Potable Water. By Floyd Davis, M.Sc, Ph.D. (Boston, U.S.: Silver, Burdett, and Co., 1891.)

THE aphorism that "history repeats itself" is being very strikingly illustrated in the matter of hygiene at the present day. Questions respecting water-supply and the public health generally, which in this country were absorbing much of scientific attention some fifteen or twenty years ago, have only within the last decade begun to be seriously dealt with even in the most civilized of Continental countries and in the United States. Indeed, although we are indebted for much of the recent progress which has been made in what may be called the theory of hygiene to our Continental neighbours, yet in matters of actual practice we still hold, undisputedly, the first place among nations. The practice of hygienic principles cannot be introduced by Act of Parliament or Imperial ukase ; it is the growth of years, or rather generations, and is quite independent of the establishment of hygienic institutes and bacteriological laboratories. In a few hours of Continental travel, it is possible to visit University towns provided with hygienic laboratories, munificently equipped, in which food-stuffs are daily submitted to elaborate analysis, whilst water and milk are searchingly interrogated as to the microorganisms which they contain ; and yet side by side with these refinements we find sanitary conditions, even in the houses of the well-to-do, which would hardly be found in the alleys and purlieus of one of our manufacturing centres. It is far from my wish or purpose to deprecate the establishment of institutions for the prosecution of hygienic inquiries on a scientific basis; on the contrary, such places are calculated to enormously accelerate the achievement of sanitary improvements, and to economize time, money, and human life, which are ruthlessly wasted when these improvements are attained as the result of empiricism and the operation of natural forces. Our position of supremacy in practical sanitation is mainly due to the long period of domestic repose and prosperity which we have enjoyed, and which has led us to turn our attention to the prevention of the unnecessary sacrifice of human beings even in civil life; but who can doubt that this position would have been much more rapidly gained if these endeavours had been always guided by scientific knowledge and systematic experimental inquiry? Even as it is, the path to our present position has been much shortened, and has been rendered less costly both as regards life and money, by the time and attention which have been bestowed upon sanitary matters by men of high scientific attainments. It is earnestly to be hoped that the recent Hygienic Congress held in our midst will have convinced those who control the purse of this country that a national effort must be made to maintain our position in the scientific as well as the practical progress of the century. We have not to

deplore any shortcoming in the quality of the scientific work which emanates from us ; in originality and as pioneers in all departments of science we are second to none; but quantitatively we are lamentably deficient, and in consequence, it is only too frequently the case that we have to leave to others the cultivation of those fields which we have ourselves had a large share in discovering. This is most conspicuously the case in the matter of hygiene; and after the highly discreditable obstruction, with which the foundation of our National Institute of Preventive Medicine was recently harassed, has now happily been swept away, we trust that public if not Government support will be forthcoming in the immediate future, to render that Institution, with its tremendous potentiality for benefiting mankind, second in usefulness and dignity to none in the civilized world. The State organization of science in the New World has made great strides during recent years, and scientific men in this country cannot fail to be impressed with the immense volume of work—more especially in applied science—which annually flows from the laboratories of the United States. The appearance of the book before us is, presumably, evidence of this great activity, showing as it does that there is a considerable body of men anxious to have presented to them in a concise and handy form all the main facts which have been accumulated—and which are dispersed in innumerable reports, blue-books, journals, and other forms of literature—concerning potable water. The difficulty of access to the original sources of this information renders such a work of great importance at the present time, but one which it is extremely difficult to do justice to. The present volume, we regret, does not come up to what we could wish for in a work of the kind. The questions which have to be discussed are in many cases necessarily more or less matters of opinion, in which conflicting evidence ought to be balanced and submitted to careful and critical analysis; unfortunately, however, for the exercise of this judicial power the author exhibits but little aptitude or inclination. The pages are sometimes filled with authoritative statements made by their respective authors on insufficient data, which statements have been copied, often not even from the original sources, without a word of elucidation or criticism. Such material, placed in the hands of the unwary reader, may lead to very serious consequences. Of this character is the statement that "the power of certain samples of water to dissolve lead is directly proportional to the number of micro-organisms that the samples respectively contain," which might well have been omitted from this work; and its introduction as almost the only piece of information concerning the action of water on lead is singularly inappropriate. Again, on another page, we are categorically informed that "even milk is sometimes the agent of this disease (typhoid fever), in which case the typhoid poison remains undestroyed in passing from the polluted water from which the cows drink, to the milk-secreting glands "; whilst no mention is made of the real mode of transmission by the watering of milk and the rinsing of cans with contaminated water. In most cases the principles laid down are sound and reasonable; but the author has permitted himself to be carried somewhat too far in his advocacy of pure water, when he says that "scientific investigation also reveals the fact that, as a community is supplied with pure water, there is not only a decrease in the disease and death-rate, but often a most surprisingly rapid increase in thrift, morality, and degree of civilization." We should be glad indeed if he were correct in his statement that since the introduction of an efficient health administration in England, the prevalence of typhoid has been reduced to such an extent that "for weeks and even months not a single case now occurs in the city of London." We can readily understand that our rivers must appear insignificant enough to the inhabitants of a country containing such mighty streams as the St. Lawrence, the Mississippi, and the Ohio; and although we are fully alive to some of them being disgracefully fouled, we certainly are somewhat startled to have our watercourses, which are dear to many of us, disposed of in the following sentences :—" The pollution of English streams is carried to such an enormous extent that the waters of many, where city sewage enters them, are actually offensive, and during the summer months, owing to the stench, the passenger traffic is forced to the railroads. In some of these streams the whole surface of the water, for some distance below sewage entrance, is in a state of commotion, owing to the evolution of gas bubbles, and the water is so foul that it cannot be used in the boilers of the little steamers that ply across the rivers. Immediately below the entrance of sewage no life can exist in the water, on account of the presence of ferrous sulphate [sic), which is a disinfectant." In dealing with the much vexed subject of the apparent self-purification of streams, the author shows a very just appreciation of the matter when he points out that there " is no guarantee that running water is perfectly wholesome at any distance below a point where it is certainly polluted with the contents of sewers and privy-vaults, or the decomposition of vegetable and animal matter. The question as to what extent must impure water be diluted or oxidized to render it safe for domestic purposes, cannot be answered. Mere dilution of polluted w.iter does not render inoperative the action of living baiiet.,1. . . ." We are glad to see that the author point • out the importance of boiling all drinkingwater which 1^ open to suspicion, for it cannot be too frequently u iteiated that perhaps the two most effective measures whi< h the private individual can take in avoiding zymotic disease consist in boiling the water and milk that are used for drinking. The largely increasing consumption (if ice, which in America has assumed enormous proportions, is a matter which also calls for very careful attention, since recent experiments have shown that, although the living bacteria in ice are considerably less numerous than in the water from which the ice has been derived, still the process of freezing, even if long continued, affords no sort of guarantee that the dangerous forms originally present in the water shall have been destroyed. Thus the bacillus of typhoid fever has been foun-l still alive in ice which had remained continuously h ■/.( n for a period of 103 days.

Percy F. Frankland.

CAUSATION OF SLEEP.

The Intracranial Circulation and its Relation to the Physiology of the Brain. By James Cappie, M.D. (Edinburgh: James Thin, 1890.) 'PHE factors concerned in the production of sleep have ■*■ from time to time engaged the attention of physiologists, and various theories have been advanced to explain the phenomena. The author of the work now before us, so far back as 1854, published a short essay on "The Immediate Cause of Sleep," which he subsequently expanded into a volume entitled "The Causation of Sleep" (Edinburgh, 1882). In the work now under consideration, although with a different title, the author travels over much the same ground as that surveyed in his previous writings on this subject, and adds to it some additional chapters.

In his successive publications Dr. Cappie accepts the I position usually taken up by physiologists, that the state 1 of sleep is accompanied by a diminished brain circulation; but he combats the view that sleep is due to a diminution of the whole mass of blood within the cranial cavity, and that the compensation for this diminution is got by an increase in the amount of cerebro-spinal fluid in the ventricular and sub-arachnoid spaces of the brain. His objection to this opinion is based upon its not being reconcilable with either the physics or the physiology of the parts situated within the cranium. As regards the physics, he adopts the view advocated by Drs. Alexander Monro (secundus), Abercrombie, and Kellie, that, inasmuch as the brain lies within a closed cavity, which possesses rigid bony walls, the contents cannot be affected directly by the pressure of the atmosphere, which can only influence the interior of the cranium through the blood-vessels, so that a force is constantly in operation to maintain the amount of blood within the intracranial vessels. The author believes that the effect of the pressure on the blood-vessels, say of the neck and head, is opposed to the movement of the blood in the veins, and that the tendency of the pressure is to keep the blood within the veins which ramify in the vascular membrane enveloping the brain, called the pia mater. At the same time, however, the arterial stream drives the blood onwards into the capillaries and the veins, which tends to dilate the latter vessels, and, in conjunction with the backward pressure on the great veins, to retard the flow of blood through the veins of the pia mater, and consequently through the great venous sinuses of the head, into the jugular veins. In this way he infers that, whilst the brain itself becomes less vascular, the mass of blood within the cranial cavity continues the same, but its mode of distribution is altered : a less proportion iswithin the arteries and capillaries, whilst an increase takes place in the contents of the veins of the pia mater. The author acknowledges, in connection with the nutrition of the brain, that molecular actions of a subtile kind take place between the blood and blood-vessels and the nervous tissues, and that these are much less active during sleep than when awake. The lessened activity in. the nutrition of the nerve protoplasm diminishes the activity of the capillary circulation. He regards, however, the change in the balance of the circulation. between the arteries and capillaries on the one hand, and the veins on the other, as the key-stone of the theory of the causation of sleep. The altered balance of the circulation occasions a change in the balance of active pressure, which is not so much within the brain substance as on the surface. It is less expansive and more compressing, and with this compression consciousness is suspended.

In proof of his theory, the author adduces observations made by Dr. Hughlings Jackson and himself on the retina—the blood-vessels of which are so intimately connected with those of the brain—both during sleep and in a state of coma, from which it would appear that in these conditions the retina was paler, its arteries smaller, but its veins were larger, more tortuous, and distended. In another case recorded by Dr. Kennedy, where a portion of the skull and dura mater had been removed, and the pia mater consequently exposed, it was noticed that the veins in the latter were during sleep congested and assumed a dark hue.

In a concluding chapter, entitled "Some Points in Mental Physiology," which was not contained in his previous work "On the Immediate Cause of Sleep," the author considers how far the peculiarities of the encephalic circulation may affect the functional activity of the different parts of the brain. Starting from the position that the brain is a composite organ, and that distinct portions are put into a state of functional activity in connection with the discharge of their respective duties, the question of balance of the circulation has again to be considered. For the part which is more immediately concerned in the production of the particular cerebral operation must become the seat of vascular excitement, and the amount of blood flowing through its vessels will be greater than that transmitted through the vessels of those other parts of the brain which are for the time being not so functionally active. Hence a certain tension of the area or centre which is actively working must arise, and the encephalic circulation is focussed in the direction of activity. The parts which surround the operating centre would act as a background of resistance, and would afford such support as will secure the immediate liberating action in the discharging centre.

The author applies his views on the encephalic circulation to the explanation of the phenomena of Hypnotism. The first incident in the hypnotic state is a steady prolonged effort of volition in which the attention is concentrated in a very restricted direction. The immediate consequence is fatigue of the nerve-centres concerned in keeping up the strain. Their molecular motions become enfeebled, the circulation through them is less active, and a condition approaching that of sleep is produced. If then, in the form of a "suggestion" from another, some stimulus calls into activity a part of the brain not fatigued in the effort of attention, the vascular activity in it will be increased, and its function will be intensified. An assertion boldly made to a hypnotized person may influence belief in opposition to former experience, and if it be towards an ideational centre, some particular notion may so monopolize the consciousness that discrimination and judgment may become almost as completely in abeyance as in ordinary dreaming.

OUR BOOK SHELF.

Physiography: Elementary Stage. By J. Spencer, B.Sc, F.C.S. (London: Percival and Co., 1891 )

As an introductory science, physiography is one requiring very careful treatment. Its range is undoubtedly wide, but it is correspondingly shallow, and should rather lead up to scientific thought than aim at giving an incoherent collection of facts. In the book before us, the author, who is head master of one of our most successful technical colleges, begins well by recommending that teachers should endeavour to make the subject a practical one, by the performance of experiments, excursions into the neighbouring country, and the collection of specimens of rocks, minerals, and fossils. The experimental shape which the book has consequently taken is one of its most noticeable features ; but it certainly falls short of the expectations raised. The chemical and physical parts appear to be excellent, but there is little to assist either teacher or student in gleaning information from the inspection of natural phenomena. A peat bog, for instance, is a fruitful subject for study under proper guidance; but this is not afforded by the scanty remarks on p. 89. In dealing with a wide subject, brevity is essential, but this does not necessitate the omission of the fundamental points, and looseness of expression. The book, however, shows many signs of a want of care in this respect. In the note on Foucault's pendulum (p. 210), for example, the whole point of the explanation is lost by the absence of a reference to the permanence of the plane of swing. On p. 113, it is stated that " submarine volcanoes produce new land, the erupted matter being piled up sufficiently high to form islands"; the omission of the qualifying word "sometimes" might obviously lead to a misconception. Test questions, original and selected, are given at the end of each chapter.

The book is well illustrated, and, with careful revision, should make a useful addition to existing text-books.

Mayhem's Illustrated Horse Doctor. Revised and Improved by James Irvine Lupton, F.R.C.V.S. (London: Griffith, Farran, and Co.)

The continued existence of domestic medicine, whether the subjects of its application be human beings or domesticated animals, cannot well be doubted. We may, however, be permitted to doubt whether true economy lies in this direction. Nevertheless, as residents in the colonies, and even in many rural districts of our own country, are often far removed from the qualified veterinarian, and considerable time must necessarily elapse before his services when sought can be forthcoming, it is obviously advisable that whatever measures are taken by the stock-owner to ameliorate the sufferings of the animal during this interval of time should be rational, and follow lines similar to those which the professional man would adopt. Wrong methods of procedure would serve only to handicap and hamper his efforts. The book before us can be recommended to guide the horse-owner in such emergencies; though we note with pleasure that the reviser, on p. 553, points out that "the reader will always best consult hi> interest and pocket by at once consulting a qualified vetenn.irian." Agreeing with this proposition, we cannot but consider superfluous the introduction of minute directions for the performance of such delicate and difficult opi-i.uions as the extirpation of the eye-ball, the division ol the plantar nerves (neurotomy) in some forms offoot-l..meness, and section of contracted tendons (tenotomy). We cm scarcely conceive an owner, however intelligent ,ind ourageous he may be, proceeding to cast, chloroform, and perform any of the above-mentioned operations.

Horse-owners will do well to note the stress which is laid upon the construction, ventilation, and drainage of

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