From the general subject of Canadian mineral resources, and the need for their development, Prof. Roberts-Austen passes to a particular metal-nickel. The splash of a falling marble which is dropped into milk, and of a gold bullet dropping into molten gold, is shown, by means of reproductions of photographs, to bear a resemblance to the splash produced upon armour plates by projectiles. To prevent the marble from entering the milk, the surface of the liquid might be hardened by freezing it. Using this illustration, Prof. RobertsAusten ingeniously explains that in a similar way an armour plate should have a face of rigid steel to break up a projectile, and a tough back to save the plate from fracture. These conditions are obtained by the addition of 4 or 5 per cent. of nickel to steel.

There are many curious points connected with the relations of iron and nickel, and several of scientific interest are described in the present volume. Every one interested in the properties of metals, or desirous of obtaining a concise and trustworthy account of Canada's mineral riches, should read what Prof. Roberts-Austen has to say upon these subjects.

Hann, Hochstetter, Pokorny-Allgemeine Erdkunde, Fünfte, neu-bearbeitete Auflage. II. Abtheilung Die feste Erdrinde und ihre Formen. Von Ed. Brückner. Pp. xii + 368. (Wien: F. Tempsky, 1898).

IN undertaking to produce a new edition of Hochstetter's share in the Allgemeine Erdkunde, Prof. Brückner very wisely determined to rewrite the whole section, and so to bring it into line with contemporary methods and results. The scope of this treatise on the crust of the earth and its forms includes a sketch of petrography, geological structure, stratigraphy, the agencies which work on the earth's surface (classed as endogenous and exogenous), the forms of the crust, and the morphology of the landsurface.

Prof. Brückner follows Richthofen and Penck for the most part; but his range is wide, and he pays due regard to the work of British and American geologists. It is particularly noteworthy that an authority who knows the Alps so well should refrain from making them the main source of his illustrative examples. In speaking of the interior of the earth the author leans to the view of the central part being in a gaseous state, the gaseous rock being reduced by intense pressure to a higher density than any liquid known on the surface; but he quotes and very impartially discusses the more generally accepted view of a solid earth due to the raised melting-point of rocks under pressure. Earthquakes are treated at some length; but the work of Milne is not referred to, Rebeur-Paschwitz being the principal modern authority cited. In discussing the origin of land-forms, more weight is given than in most text-books with which we are familiar to the importance of tilted or vertically displaced blocks of crust, and relatively less importance is attributed to folded structures. In treating of the régime of rivers and the classification of land-forms, Prof. Brückner follows Penck closely.

A number of useful references are given to special works treating on the special departments under notice; and it is gratifying to find a fair proportion of English books amongst those cited. In speaking of caverns, however, the author fails to mention M. Martel's important researches, or to refer to the Speleological Society. The revision of the work is very thorough; the only serious misprint of proper names we have noticed is the citation of the author of the Mundus Subterraneus as "Kirchner" in place of "Kircher."

This important work, so well-written by a master of his subject, is simply one amongst many German books on physical geography, a class still very poorly represented in the English language. H. R. M.

Elementary Botany. By Percy Groom, M.A., F.L.S. Pp. x + 252. (London: G. Bell and Sons, 1898.) IN his preface the author explains that his object has been "to place the subject before elementary students in such a way as to exercise to the full their powers of observation, and to enable them to make accurate deductions for themselves from the facts which they observe." The book is written on the assumption that a compound microscope is not employed; and in the section on physiology no knowledge of the histology of plants is assumed. There are already numerous books more or less suitable as guides to the student of elementary botany, some of them so excellent as to leave little, if anything, to be desired in their special fields. But they either omit a good deal that might readily enough be examined and verified even by beginners, or they require such a use of the compound microscope as is scarcely practicable in the teaching of botany in schools. A book on the lines indicated by Mr. Groom should prove very helpful alike to beginners and to teachers, and would doubtless be welcomed if felt to be the result of adequate personal experience. we cannot altogether congratulate the author on his success in carrying out his objects, despite the merits of his work, especially if it is intended as a school-book. Children can scarcely be expected to benefit as much from the study of general morphology as from the examination of selected plants, in which they could observe and gradually become familiar with the various structures and life-histories.

But

The definitions of terms are at times scarcely in keeping with general usage; for example, those of compound leaves, astivation and vernation, and compound fruits. It may be questioned whether the statement-"that portion of a single flower which persists after fertilisation until the seeds are ripe is termed the fruit "-rs preferable to the usual definition. The classification of fruits also is unsatisfactory.

Such a statement as that "a root can only produce as lateral members branches like itself" is misleading, and indicates want of care. The production of buds by roots can easily be verified; indeed, the author refers to their growth on roots under "adventitious shoots."

a

In the physiology a knowledge of chemistry is assumed to an extent beyond what is to be looked for in many schools. In consequence a good deal of this section could be little more than words to those for whom the book seems to be intended. The plants treated of all belong to the flowering plants, though there seems nogood reason why representatives of the larger cryptogams should not find a place in such a work. But the task of censor is unpleasant; and although it has been necessary to criticise what must impair the usefulness of the book, we gladly recognise that it should often be found suggestive by teachers and others possessed of sufficient knowledge to avoid being misled where the risk exists. The book is well printed, and is of very convenient size, and the illustrations are good and numerous; but it would have made them more useful had some of them been repeated where more than once particularly referred to and explained. References to figures, sometimes many pages back, are apt to be irritating.

Alembic Club Reprints. No. 13. The Early History of Chlorine. No. 14. Researches on Molecular Asymmetry. Pp. 46 and 48. (Edinburgh: W. F. Clay, 1897.) THE first of these reprints contains translations of papers by Carl Wilhelm Scheele (1774), C. L. Berthollet (1785), Guyton de Morveau (1787), and J. L. Gay-Lussac and L. J. Thenard (1809). This volume, together with the earlier reprint in this series (No. 9), containing Davy's researches, completes the history of chlorine from its discovery by Scheele to the proof of its elementary nature by Davy. The importance of this discussion upon the

development of chemistry is obvious, but it is somewhat difficult to step back from what is now common-place knowledge, to the standpoint of these early pioneers. The paper of Scheele, although worded in terms of the theory of phlogiston, is remarkable for its terseness and lucidity, and for the clear and correct ideas expressed upon the nature of the new gas. Indeed, if the word hydrogen be substituted for phlogiston, Scheele's explanation of the action of hydrochloric acid upon the black oxide of manganese almost represents our present knowledge. Berthollet, on the other hand, writes very voluminously upon a very slender experimental basis, and as an ardent exponent of the views of Lavoisier, concludes that chlorine gas is the oxide of an unknown radical, and this fixed idea leads to quite erroneous interpretations of observed facts.

That the effect of a preconceived idea, however, is not always prejudicial, is shown in the two lectures by Pasteur on Molecular Asymmetry, which form the contents of the second of the reprints under notice. Here Pasteur distinctly states that but for his preconceived idea as to the inter-relation of hemihedry and rotatory phenomena, he would not have discovered the opposite hemihedry of the paratartrate and tartrate of soda and ammonia; a difference missed by so careful an observer as Mitscherlich.

The English translation of these famous lectures possesses all the charm of the original. In them we have a complete account of Pasteur's work on optically active compounds, and, as the editor states in the preface, it is remarkable that the three ways of separating optical isomers here described are still the only ones known, and that there is scarcely a statement which would be changed if the whole were to be written to-day. Practical Toxicology for Physicians and Students. By Prof. Dr. Rudolf Kobert, late Director of the Pharmacological Institute, Dorpat, Russia. Translated and edited by L. H. Friedburg, Ph.D. Pp. xiii + 201. (New York: William R. Jenkins, 1897.) THE work before us is a translation of a book by Prof. Kobert, the second edition of which was issued in 1887. While the author was engaged upon his "Lehrbuch der Intoxicationen," by which he is for the most part known in this country, and with which the present work must not be confused, he allowed the latter to run out of print. In 1894 he wrote the third German edition, and it is this which Dr. Friedburg has now translated and edited, three years after its issue. As we have not had the opportunity of seeing the third German edition of the original, we are unable to measure either the quality or extent of Dr. Friedburg's editing. With regard to his translating, it is the worst which has ever come under our notice. In fact the English language, in Dr. Friedburg's hands, is extremely difficult to understand. As this is a very strong statement it behoves to give an instance, which, by the way, is not the worst we could find. Dr. Friedburg is speaking of a rise of blood pressure of peripheral origin. "If this is the case, the rise must obtain after the injection of the poison into the blood of an animal even if the marrow of the neck has been cut through and whose spinal marrow has been drilled out." We quote this instance, since it shows that the author is not only deplorably ignorant of the English language, but has no knowledge of the English equivalents of German physiological expressions. Dr. Friedburg's Latin is no better than his English; the plural of vagus is always written "vagii," and so polymorphic is the declension of this noun that we find the nominative singular written "vagis."

us

To turn from the manner of the book to the matter, it is undoubtedly full of information, and, if properly translated by some one acquainted with pharmacological method and the English language, would be valuable to both the pharmacologist and toxicologist. F. W. T.

Pp.

What is Life? or, Where are we? What are we? Whence did we come? and Whither do we go? By Frederick Hovenden, F.L.S., F.G.S., F.R.M.S xiv 290. (London: Chapman and Hall, 1897.) MANY matters are dealt with in this book, ranging from the stellar universe to cell structure. About half the text is made up of quotations from the writings and utterances of men of science, distinguished and otherwise, and the remainder consists of perplexing conclusions which the extracts are held to support. Excessive zeal is shown in establishing fundamental truths, but that may be forgiven. It is when the author expands into the ether, so as to embrace in his comprehensive idea such diverse subjects as the Pentateuch and the currency question, that we lose the connections of the argument. The chief conclusions arrived at are stated in the following words :

"From the combining power of the strongest species of atoms under the influence of Ether, arises the formation of cells.

"Cells under the influence of the strongest cell group themselves to form highly complex structures or organisms, hence the most complex of all organisms-Man. The activity of cells forms that activity we call Human Life. Thus Life is the sum of the activity or energy of molecules formed of atoms.

"The power of the regeneration of molecules causes regeneration of cells, and this causes regeneration of

Life. Life is eternal."

La Tuberculose et son Traitement hygiénique. Par Prosper Merklen, Interne des hôpitaux de Paris. Edited by Felix Alcan. Pp. 190. (Paris: Ancienne Librairie Germer, Baillière et Cie.)

THIS little book forms No. cxix. of the "Bibliothèque Utile" series, and is certainly calculated to serve a useful purpose. It addresses the public, and not the medical profession. The nature of tubercular disease is very clearly and accurately set forth in plain language, together with its chief manifestations in man, and the principles underlying its prophylaxis and treatment. It is indisputably true that in the case of a preventable disease like tuberculosis, which constitutes one of the main scourges of civilised man, a dissemination of sound knowledge on the subject is the first necessary step in educating public opinion up to the hygienic requirements and sanitary restrictions which are demanded to check its spread. The present brochure is a creditable effort in this direction: the author has succeeded in placing home truths on the subject in a very clear light, and his remarks cannot fail to be of direct benefit to the public.

Marriage Customs in Many Lands. By the Rev. H. N. Hutchinson, B.A., F.G.S. Pp. xii + 348. (London: Seeley and Co., Ltd., 1897.)

The

MR. HUTCHINSON, forsaking geological subjects for a time, presents in this volume a purely popular account of the quaint customs connected with marriage in many parts of the world. He has not attempted to discuss the scientific questions relating to the history and origin of human marriage, but has merely aimed at providing the general public with readable descriptions of curious nuptial ceremonies of various peoples and races. readers for whom the volume is intended will find much to interest and amuse them in it; and the excellent illustrations-among the best of their kind-give the book additional attraction. Authorities may not agree with all Mr. Hutchinson says; but, as the book is a compilation, the mistakes are usually the mistakes of the sources from which the information has been derived, and the only criticism that can be offered is whether the author has exercised sufficient discrimination in the collection of material.

LETTERS TO THE EDITOR [The Editor does not hold himself responsible for opinions expressed by his correspondents. Neither can he undertake to return, or to correspond with the writers of, rejected manuscripts intended for this or any other part of NATURE. No notice is taken of anonymous communications.] Misleading Applications of Familiar Scientific Terms. MAY I, not as an expert in science, but as one who has made some research into the conditions of lucidity, venture to thank you for the protest which appears in your current number against a misleading application of the familiar term "Light"? This is not of course the only instance of the kind; but it seems especially regrettable as tending, by the very success and popularity of the Lectures reviewed, to introduce gratuitous confusion into youthful minds.

66

I may perhaps be pardoned for adding that I was fortunate enough in my little book, "Grains of Sense," published last year, to anticipate the verdict of your reviewer, and to point out how much, in this and similar cases, such modes of expression on the part of scientific men tend on the one hand to diminish our precious and too slender store of clearness of thought, and on the other to hinder the progress of science itself. V. WELBY.

April 1.

The Kinetic Theory and Radiant Energy. IN the course of the discussion which took place in your columns during the winter of 1894-5 on the kinetic theory of gas es, emphasis was rightly laid on the difficulty of reconciling the law of partition of energy among the different degrees of freedom of molecules of gases with the large number of such degrees of freedom indicated by their spectra, and, generally, of explaining, on the kinetic theory, the relations between matter and the ether required to account for radiation. It was even suggested, by one writer, that the ether, with its vastly larger number of degrees cf freedom, must ultimately absorb all the energy of the molecules. I instanced the case of a sphere moving in an infinite mass of perfect liquid as exemplifying a system where no such ultimate absorption of energy would take place, and pointed out that everything depended on the laws according to which transference of energy took place between the molecules and the ether.

The object of this letter is to show that the subsequent discovery of the Röntgen rays has suggested a theory of the radiation of heat which may possibly throw considerable light on the difficulties referred to by affording an answer to the question, "If the temperature of a gas is proportional to the mean translational kinetic energy of the molecules, how comes it that this kinetic energy can be transferred from one set of molecules to another by radiation through the ether?"

Consider the Röntgen rays: we know, firstly, that they are produced by the impact of the kathodic rays on the Crookes' tube, these latter consisting not improbably of streams of bombarding molecules; secondly, that they not only have the power of discharging electrified bodies, but also of modifying the electrical state of gases in such a way as to enable these to discharge bodies. In this modified air, to which Villari has applied the somewhat barbarous name of "aria Xata" "xd. air," some kind of dissociation of the electrons must necessarily have taken place.

or

Arguing from analogy the idea suggests itself that the encounters between molecules of a gas, no less than the kathodic bombardments, may give rise to radiations, and these, too, when falling on another mass of gas may modify the electrical state of its molecules in such a way that their original electrical state is only restored by encounters between them.

Now taking, as a simple illustration, two oppositely electrified perfectly elastic conducting spheres; as these approach one another, they acquire kinetic energy in virtue of their attraction. On coming into contact they are discharged and the attraction ceases, so that their kinetic energy of separation is greater than that which they had previously to coming within each other's influence. Again, when a charged and an uncharged body impinge, the charge is distributed between them; they repel one another as they separate, and again acquire an increase of kinetic energy-as in the ordinargy pith-ball experiment.

It follows that the incidence of rays possessing the property suggested above will tend to increase the temperature of a gas. The discharge which takes place at an encounter will, however, be an oscillatory one, and will lead, therefore, to further generation of undulatory rays.

Considering two masses of gas at unequal temperature, the impacts in the hotter gas, being the more frequent and violent, will give rise to the more copious emission of rays, and these falling on the cooler gas, will produce the greater electric dissociation resulting in the greater acquisition of kinetic energy in collisions between the molecules. The feebler rays from the colder gas will have less effect on the molecules of the hotter and the kinetic energy supplied in this way will not compensate for that lost by radiation. Thus the theory of exchanges" will hold good.

one,

A still more important consequence of such a theory is that no interaction will take place between the ether and molecules except where there are encounters between the latter, and, moreover, the interactions which occur in an isolated mass of gas will not affect the translational velocity of its centre of mass, nor the angular momenta about axes through its centre of mass. Thus it results that the celestial bodies go on in their course experiencing no resistance whatever from the ether.

On the other hand, the fact that light from distant stars is not absorbed before it reaches the earth, no longer implies the complete absence of matter in interstellar space. Isolated molecules will absorb no energy from the ether; and so long as the molecules moving about in interstellar space are assumed to be so few and far between that collisions practically never occur, there will be nothing to impede the passage of light or heat rays. It is only when such rays fall on assemblages of molecules sufficiently dense to possess the attributes of what we call matter-as, for example, when they reach our atmosphere— that absorption of energy will take place.

The phenomena of irreversibility and of degradation of energy would thus, so far as the present view goes, be restricted to material bodies, and hence the conditions necessary for the existence of life on our earth may have been brought about without the enormous waste of energy which would be required in the absence of some such theory.

A photo-voltaic theory of photographic action formed the subject of exhaustive experimental investigation at the hands of Herr Luggin last year, and photo-voltaic theories of vision have also been proposed. It would thus seem that the analogy between the action of heat rays, visible-light rays, ultra-violet rays and Röntgen rays may be complete. The question still remains, how are ethereal waves able to affect the electric state of assemblages of molecules? But since Röntgen-ray physicists have proved that they do this, the question has to be faced in any case. It is now rendered no more difficult, and, on the other hand, our theories of the relations between ether and matter are simplified by referring radiation of heat to the same phenomenon. G. H. BRYAN.

Note on Mr. Wood's Method of Illustrating Planetary Orbits.

I FEAR that Mr. Wood's beautiful method of illustrating planetary orbits by means of a bicycle ball rolling on a glass plate about the pole of an electro-magnet (NATURE, April 29, 1897), has rather fallen into disrepute in the minds of many physicists since its criticism by Mr. Anderson in NATURE, May 13, 1897. Mr. Anderson there states that the law of attraction in such a case would be that of the inverse fifth power of the distance. This could only be true if the ball were of very soft iron. A bicycle ball is far from this, and becomes strongly magnetised after brief use in the experiment, behaving like a permanent magnet of great coercive force. Under these conditions the attraction between the pole and the ball will vary approximately as the inverse third power. There is also another factor to be considered. If the true pole lies below the glass plate, only a certain component of the total force is active in producing the attraction towards the centre of motion. To determine what the law of variation of this component will be, I have had one of my students take a number of series of observations on the attraction of a bicycle ball along a plane perpendicular to the axis of a magnet.

In the experiments the magnet was horizontal, and the bicycle ball with its magnetic axis vertical was fastened to one end of a strip of spring brass, the other end of which was clamped fast in

a sliding clamp so as to be raised and lowered. The bending of the brass strip under the attraction of the magnet on the ball was measured by means of a telescope and scale, the mirror being fastened to the end of the strip. As the motion of the ball was entirely in a plane perpendicular to the axis of the magnet, the law of variation of force must have been very nearly the same as in the orbit experiments.

When the ball was directly over the true pole, which lay about 1 cm. from the end of the conical pole-piece, the law was nearly that of the inverse cube, the observations being taken between the limits of 3 cm. and 14 cm. from the axis of the magnet. Other series were taken with the plane of motion of the ball at different distances from the pole, and it was found that with the plane of motion at 2.8 cm. from the true pole the law of the inverse square was very closely obeyed between 4 cm. and 14 cm. from the axis. These limits cover the region in which the orbits would in most cases be formed. The exact law of force as determined by least squares from seven observations between the above limits was that of the 21 power of the distance. LOUIS W. AUSTIN. The University of Wisconsin, Madison, Wis., March 16.

An Extraordinary Heron's Nest.

66

I SEND you a photograph of probably the most extraordinary heron's nest ever discovered in this or any other country. During a gale it was blown from the top of an elm tree in the heronry on Stoke Hall estate in Notts, the seat of Sir Henry Bromley, Bart. It is of unusual size, and almost exclusively composed of wire of varying lengths and thickness; the centre, or cup,' alone being composed of fine twigs, grasses and feathers. Several other nests of the heronry, which had also been blown down, contained pieces of wire cleverly worked in with twigs in the usual way, but this was the only one entirely composed of that material, as far as the main structure is concerned. There are happily now a very flourishing heronry at Dallam Tower, Westmorland, the seat of Sir Henry Bromley's son, Mr. Maurice

166

5'2

The accepted fatality before Jenner's birth was
There were-
Cases. Deaths.
9

Re-vaccinated cases at Gloucester 173 These had all kinds of v. marks up to 8 in number, and some had been repeatedly re-vaccinated; one "often" re-vaccinated. If the same energy had been put into a critical proof of the vaccination of each one as was into avoiding condemning vaccination, there would be little to show, even in fatality, in the above for vaccination; as it is, it kills every vaccine dogma.

ALEX. WHEELER.

MR. WHEELER, it must be assumed, is wishful to prove that the fatality amongst the vaccinated is as high, or at any rate is not lower than amongst the non-vaccinated. It is surely not necessary for him to separate vaccinated cases into those "with marks" and those with "no marks," since to him it should be immaterial whether a patient be vaccinated or not.

Taking Mr. Wheeler's own classification, we find that of the unvaccinated cases, 679 in number, 287 died, giving a percentage mortality of 42'2; whilst of the vaccinated cases, 1300 in number, only 147, or 11'3 per cent., died. These figures should surely be enough to settle the question as regards percentage mortality, and the mere inclusion of the 21 cases and 10 deaths, whose description includes the word "vaccination' or "vaccinated," does not in any way invalidate the general conclusions to be drawn from these figures.

If now, however, a class for the "under-vaccinated" be included, the second class may be divided into "under-vaccinated" 89 cases with 27 deaths, or 30'3 per cent., and vaccinated 1211 with 120 deaths, giving a mortality of only 9'9 per cent. It is evident that Mr. Wheeler's table in no way conflicts with the figures given in the Report (except in one small particular, noted below), but is based on a misconception of the term

and on

for very many years, and with several other heronries in various parts of the country, I never knew of the birds using wire in the construction of their nests. I have several records of rooks using wire in large quantities in the construction of their nests. Particulars of one very remarkable instance were published in the Yorkshire Weekly Post of May 19, 1894, and of another in the same paper for June 23, 1894. Both of these freaks took place in India: one at Calcutta, the other at Ran. goon. The other curious feature of the Stoke Hall phenomenon is that there is, and never has been, any lack of ordinary building material, and that all the wire used must have been carried a great distance. G. W. MURDOCH.

Westmorland.

"The Story of Gloucester." REFERRING to your article (p. 221), I think you cannot have looked at pages 70 to 117 of the Gloucester Small-pox Epidemic Blue Book, by Dr. Coupland. I have analysed all these cases, and here is the result.

term to signify those cases of small-pox which had undergone vaccination at any time within the (generally accepted) period of incubation: i.e. fourteen days before the appearance of the rash. In the list of "unvaccinated" cases are included a few which were actually vaccinated in the invasion period. No doubt some of these should be placed in the vaccinated class; but others, again, should be grouped in the unvaccinated class. The Royal Commission reckoned the whole group, instead of a large proportion, in this latter class, which is perhaps not strictly scientific and accurate. Mr. Wheeler, however, goes far further astray in including them all in the vaccinated class, which is clearly erroneous. It may be pointed out in this connection that, in his recently published work, Dr. Cory gives some most interesting facts which tend to show that vaccinal immunity is not obtained until nine days have elapsed after inoculation. It would be easy, therefore, from the table on page 149 of the Report, to divide the total 89, there reckoned asunder vaccination," into two sections: (a) those vaccinated before, and (b) those vaccinated within eight days, of manifesting small-pox. If this were done, there would be added (a) to the

Mr. Wheeler's table.

"vaccinated" class 10 cases with 3 deaths; and (b) to the "unvaccinated" class 79 cases with 24 deaths.

Without checking Mr. Wheeler's figures by laboriously going through pages 70-117 of the Report, it is simply necessary to deduct those "under-vaccinated" from his several lists. His classes of "no marks" and "?marks" correspond with Dr. Coupland's groups of "alleged" and "doubtful" vaccination, except that Dr. Coupland's figures give one case less and one death more than Mr. Wheeler's. Although it is highly probable that many of these uncertain and doubtful cases were really unvaccinated, the Report includes them, as does Mr. Wheeler, in the "vaccinated" class (see page 153, &c.).

unvaccinated 255; this, too, in families of the same class, in the same streets, and living under similar sanitary (or unsanitary) surroundings as those in which every child was unvaccinated. May we not legitimately infer that had all the Gloucester children at these ages been vaccinated, only 1/7th of those that did suffer would have suffered, and the mortality would have been less than 1/60th of that to which it did attain? Vaccinators are said to be incapable of viewing this subject impartially, but Dr. Coupland is most judicious in the handling of his figures, and it is apparent that the evidence that he has collected from careful observation weighs with him as much or more than do the figures he has brought together; and it is certain

It is difficult to grasp Mr. Wheeler's point in presenting the figures in this way. It might be useful if these questionable cases had all been turned over to the "unvaccinated" class; but why does he detach them from the rest of the admittedly vaccinated? He could not have intended to show, as his own figures do, that post-vaccinal fatality diminishes with a rise in the presumed greater efficiency of vaccination as evidenced by the number of scars. Dr. Coupland does not enter into the question of marks. It has been done over and over again, and in both his Dewsbury and Leicester Reports Dr. Coupland makes a most valuable contribution to this question. The main object of the inquiry at Gloucester was to determine the broad question of the occurrence and fatality of small-pox in the vaccinated and unvaccinated.

Perhaps the most important point that the Gloucester epidemic illustrated is one that is passed over by Mr. Wheeler, and one which unfortunately appears as though the opponents of vaccination in their pursuit of a fad had become callous to the fate, in this instance, of the Gloucester children, but also of the children wherever there is an outbreak of smallpox.

About the effects of the vaccination or non-vaccination of children there can be no dispute. In this connection it is only necessary to refer to the figures of those attacked between one and ten years of age, and especially at the incidence rates given near the end of the Report. Indeed, if only those households are taken in which some vaccinated children are to be found, it appears that the incidence of small-pox among the vaccinated children was only 10 to 100, though amongst their unvaccinated brothers and sisters it was 10 to 14; whilst the death rate (per 1000 of those exposed to infection) was for the vaccinated less than 4, for the

that if those who deny the efficacy of vaccination could have the experience that he has had, they would cease to hold the view that he is prejudiced. Any one who considers his Report judicially must confess that he has presented the facts extremely fairly and impartially, and that he evinces far less bias than those who, on very slight and shadowy information, are undoubtedly unreasonably opposed to vaccination-the very people, in most cases, who bring the charge of partiality. Every one knows that where large numbers of statistics have to be collected, errors of fact may creep into records, and that, with fuller knowledge, slight modifications may have from time to time to be made. As regards the main facts of Dr. Coupland's records, however, the most exacting will find it difficult to trace any important inaccuracy. In respect to the records concerning children the facts are indisputable, and lead to the mournful conclusion that amongst these there would have been vastly less suffering and far fewer deaths in the Gloucester epidemic, had not infant vaccination been so widely neglected.

As regards re-vaccination it is difficult to see how Mr. Wheeler obtains the figure 173. In the table (p. 46) there are given 190 who were stated to have been re-vaccinated. Assuming that each of these was really and efficiently re-vaccinated-a large assumption

the fatality would be 4'7, or much below the general vaccination rate. There are, however, several difficulties to be sur mounted before a satisfactory demonstration of the relationship of re-vaccination to small-pox can be arrived at ; and one of these especially, that of the true interpretation of a failure "to take," is a most important one. This failure "to take" does not necessarily imply that the subject is immune. Then there is also the fallacy of recent re-vaccination which, like recent primary vaccination, may have been done too close to the date of the