account of the two-stream theory, based mainly on Prof. Eddington's own researches, is given. The mathematical foundation of this theory and of Schwarzschild's ellipsoidal hypothesis is placed in a separate chapter, an excellent arrangement from the point of view of the general reader. The unmathematical reader must also pass over much of the statistical investigations in chapter x., though to the mathematician the application of the theory of integral equations to statistics will be particularly interesting. Except in these two sections the general reader should have no great difficulty in following the main line of the argument. Other chapters deal with those remarkable phenomena which are associated with the spectral classification of the stars, and which constitute the most significant discoveries in recent astronomy; the difficult problem of counting the stars in the sky according to magnitude, based largely on recent work at Greenwich, but paying perhaps an exaggerated respect to a well-known memoir of Kapteyn; and finally, the attempts which have been made to explain the stellar system in dynamical terms, attempts which seem rather premature in view of our still imperfect knowledge of the kinematical relations.

In conformity with the editorial scheme of the series to which it belongs, the book conveys throughout a strongly personal view, from which at some points the reader may be tempted to differ. But it is on the whole an eminently sane view, and this means much when in the nature of the case provisional judgments alone are possible. Ideas are in a state of flux, and gratitude is due to Prof. Eddington for fixing the phase of the moment in a permanent, accessible form. H. C. P.

THE ENAMELLING INDUSTRY. The Raw Materials for the Enamel Industry and their Chemical Technology. By Dr. J. Grunwald. Translated by Dr. H. H. Hodgson. Pp. viii+225. (London: C. Griffin and Co., Ltd., 1914.) Price 8s. 6d. net.

THE

HE preparation of enamels for the purposes of ornament dates from a very remote period; we find them in use in ancient Egypt and Babylon, although in the earliest known specimens they were used as inlays in the metal objects they adorned, and not melted on them until somewhat later times It is not, however, until the beginning of the nineteenth century that the coating with enamels of iron hollow wares, saucepans, and the like for domestic use was practised, a process that many years afterwards was applied to the enamelling of iron in sheets and plates. The materials dealt with by the author are those

employed in the manufacture of enamels for these purposes on a commercial scale.

The economic importance of the industry on the Continent is evident, if we consider that it gives employment in Germany to 25,000, and in Austria-Hungary to 19,000, persons; and a large part of the output finds a market in England.

The appearance of a translation of Dr. Grunwald's book is opportune at the present time, when methods are being discussed for the satisfactory organisation of our industries and the equipment of works, with the object of producing articles which hitherto have largely or entirely been made in other countries.

Its perusal brings forcibly to our notice the part which science has played, and is playing, in the management and control of the processes of the enamelling industry, and that complete success can only be attained by the co-operation of science and practical skill. Much scientific investigation, however, is still needed before certain hindrances to the success of many of the operations of the enameller can be successfully grappled with.

The object of the book is to supply those engaged in enamelling works with an account of the composition, properties, and limitations of use of the various materials employed and of their practical application on a large scale. An exact knowledge of these, it is scarcely necessary to point out, is absolutely essential in order to overcome the difficulties which often arise in works' procedure.

SO

Much of the information contained in the book, it may be said, can be found in works on mineralogy and applied chemistry, but it is scattered that, for purposes of reference, it is practically inaccessible to the busy worker.

The chief materials dealt with are the felspars, quartz, fluorspar, borax, cryolite, the alkalies, and the various agents for colouring and for giving opacity. The composition and properties of each are given at some length, and the nature of the impurities liable to be present and their effects on the character of the enamels are clearly set forth.

A point of practical importance is emphasised as regards the felspars that, as a rule, it is inadvisable to replace felspar silica by quartz or clay, even although the equivalent proportions are observed. In this connection it is well known that in enamels, as in many other substances, identity in chemical composition is often accompanied by considerable divergence in physical properties.

The author has evidently had considerable practical experience in enamelling, and the remarks appended to the description of each of the materials on their rôle and application in works'

The accounts given, however, of the preparation of the materials are in a few cases of doubtful value, and in the case of the metallurgy of tin even inexact. It is, too, not obvious what useful purpose can be served by the introduction of the graphic formulæ of the felspars.

These are, however, minor defects. The book is a good one, and the appearance of a translation into English has rendered the industry in this country a valuable service. It should be in the hands of everyone connected with enamelling works. W. G.

NEW BOOKS ON CHEMISTRY. (1) Van Nostrand's Chemical Annual, 1913. Edited by Prof. J. C. Olsen. Pp. xiv+669. (London: Constable and Co., Ltd., 1914.) Price 12s. 6d. net.

(2) A Text-book of Chemistry. By W. A. Noyes. Pp. xv+602. (London: G. Bell and Sons, Ltd., n.d.) Price 8s. 6d. net.

(3) The Electrical Conductivity and Ionisation Constants of Organic Compounds. By Dr. H. Scudder. Pp. 568. (London: Constable and Co., Ltd., 1914.) Price 12s. 6d. net.

(1)

1) "VANO AN NOSTRAND'S Chemical Annual

for 1913" is arranged on much the same lines as the well-known German "Chemiker Kalendar" of Biedermann. It contains a great number of tables of constants and a vast amount of other information useful to chemists. It is, in short, the kind of reference book which no practical chemist can afford to be without; for the amount of time it must save will soon repay him for its rather high price.

Seeing that the bulk of each annual issue is a mere copy of a former one, it seems as if something could be devised whereby the small amount of new matter and corrections might be published separately without the expense of repurchasing the whole volume. The present issue is embellished with an excellent portrait and a short obituary notice of Prof. Henri Moissan.

(2) A text-book written for beginners is always difficult to appraise at its true value unless one has some notion of the character and extent of the oral and practical teaching which necessarily accompany it. As it stands there is little to find fault with in this volume, either in regard to the arrangement of subjects, the descriptive portion, or the facts, yet unless there is a great deal of amplification we have grave doubts if it could be recommended unreservedly as a satisfactory first text-book. The matter is condensed into short

We find, for example, in the first hundred pages or thereabouts, in addition to much experimental information, accounts of the ionic theory, equilibrium, reversible reactions, catalysis, valence, the phase rule, the atomic theory, the van 't Hoff-Le Chatelier law, molecular volumes, etc. Even the "quantum theory" is introduced later in a paragraph of fifteen lines, and we have no hesitation in saying that, in so far as it attempts to convey any information, it is so much wasted space.

The book is, in short, a multum in parvo, no doubt excellent as a summary of many and divers facts and theories.

We would ask again, as we have frequently done in reviewing other elementary text-books, whether any object is served by introducing at the beginning definitions and generalisations of the nature of which the student has as yet only vague ideas? Is anything substantial to be gained by stating (p. 5) that matter is anything which has mass, or that matter is anything which requires energy to set it in motion, when, on the next page, energy is defined as anything which may set matter in motion?

A great difference is often observed in the attitude of students towards physics and chemistry, and the reason probably is that in the one he is taught to reason logically, because he is made to think logically; in the other he is confronted with phenomena about the nature of which he is rarely encouraged to express his opinion, because he is provided, often unconsciously, with the explanation. The paragraph on elements and compounds (p. 9) affords an illustration. "If the red oxide of mercury is heated in a small tube, metallic mercury will distil, whilst a glowing splinter held at the mouth of the tube will burst into flame. The heat causes the decomposition of the oxide of mercury into mercury and a gas which is called oxygen."

It is a gratuitous assertion that the phenomenon is one of decomposition; why not say with the old phlogistonists that the red powder has combined with something in the air to form the metal and left the oxygen? Until the loss of weight is recognised this explanation is equally logical; but then, of course, if we begin by calling the substance oxide of mercury we merely end by proving what we have tacitly assumed at the outset.

(3) Dr. Scudder's book is a complete bibliography of the ionisation constants of all the organic compounds which have appeared from 1889 to 1910 inclusive, with corrections down to 1913. That the work involved in compiling these tables must have been enormous may be estimated from the author's statement that 78 journals and

OUR BOOKSHELF. Boilers, Economisers, and Superheaters: Their Heating Power and Efficiency. By Prof. R. H. Smith. Pp. viii+128. (London: Crosby Lockwood and Son, 1915.) Price 7s. 6d. net. THE author's purpose in this book is to provide material whereby the designer of steam boilers may take account of the transmission of heat by radiation from the incandescent fuel and the incandescent parts of the flame in as full and scientific a manner as the data at present available makes possible. It is assumed that combustion is completed within, or close to the surface, of the mass of coal, and that the heat so produced is divided between heating the solid coal and heating the generated gases. This assumption enables the furnace gas temperature to be calculated for various ratios of air actually admitted to the furnace to the air required by chemical theory, and for various heating values of the fuel. The result indicates that the temperature depends almost solely upon the air ratio, and to a minute degree only upon the heating value of the coal. The heat given up by the gases passing along the flues is then dealt with and similar calculations are given for economisers; applications to superheaters form the subject of a separate chapter. The laws of heat transmission in boilers are too complex for ready use in engineering drawing offices, and the author has reduced these laws to the form of diagrams. It is unfortunate that these diagrams, while showing the way in which the quantities involved vary, are reproduced to a scale too small to be read accurately; the reader interested in boiler design is invited to purchase copies of the original large-scale diagrams. There is a great deal of interesting and useful matter in the book, but it is not presented in a very readable form, and the practical designer is likely to consult the diagrams much more frequently than he will refer to the text.

Through the Grand Canyon from Wyoming to Mexico. By E. L. Kolb. Pp. xix + 344. (New York: The Macmillan Co; London: Macmillan and Co., Ltd., 1914.) Price 8s. 6d. net. THIS is a graphic but unassuming account of one of the very few successful descents through the country of the Grand Canyon by boat from end to end. For European readers it should have contained a map, to ensure the appreciation of the

vast distances involved and the remoteness from civilisation of the plateau-heights on either hand. Anyone who has travelled along gorges, such as the Bosnian canyon of the Vrbas, will realise the effect of a sudden contact with the outer world, where some trail descends by a gentler part of the valley-side, finds a passage across the river, and climbs again to the upper air. Such episodes, leading to the visiting of ranches where pioneers and outlaws still lead unhampered lives, broke the long series of hazards which the fearless author and his brother set before themselves. No two of the cataracts are alike, and the tale is so well told that the reader feels himself limited by rock-walls 4000 ft. in height; he sees the huge fallen blocks that seem to bar the passage, the spray rising from some swift descent ahead, the fierceness of which cannot yet be adequately gauged; he feels the whirl of the water round him in the rapids, where the boat twists like a porpoise in green waves; and at the end, among the sand-bars and marshes close to Needles, after a hundred-and-one days of travel, he takes leave of his guides with a genuine and affectionate regret.

The brothers Kolb are professional photographers, as the fine illustrations in this book SO amply testify. The famous journey of J. W. Powell in 1869 is, of course, fully acknowledged, and references are given to Stanton, Galloway, Stone, and to the nameless trappers or prospectors who are known to us only by shattered boats or bleaching skeletons in the gorge. geological study of the district has aptly influenced Mr. Kolb's descriptions, and seldom has a great adventure, carried out with skilled endurance, been told so simply and with so fine an absence of self-regard. GRENVILLE A. J. Cole.

Pumping by Compressed Air. By E. M. Ivens. Pp. vi+244. (New York: J. Wiley and Sons, Inc.; London: Chapman and Hall, Ltd., 1914.) Price 12s. 6d. net.

IN compiling this book the author has had the advantage of being able to draw on considerable practical experience derived from installing and testing air lifts operating under a wide range of conditions. Very good and clear descriptions are given of various types of displacement pumps, return air systems, air lifts, and pumping systems generally. Of particular interest are the sections dealing with the air lift. In this system a long vertical pipe is led down the well, and has an open mouth near the bottom and under the waterlevel, so that normally the water stands at a considerable height inside the pipe. Compressed air is led down the well by a separate pipe, and is discharged through suitably shaped orifices into the first-mentioned pipe at a point well below normal water-level. The ascending bubbles of air cause an upward flow of water, which is finally discharged into a tank at or above ground-level. The theories of Harris and of Lorenz regarding the action in air lifts will be found in the book, together with much matter of practical interest. The practical treatment is good, and forms a

useful addition to a subject the literature of which is not extensive.

In dealing with the more theoretical matters concerning the laws of expansion and compression of gases the author is not so fortunate, and there

are a number of loose and careless statements. Thus on p. 160 we find Boyle's law stated as follows: At constant temperature the volume of gas is proportional to the absolute pressure. The author is not unaware of the fact that the volume is inversely proportional to the absolute pressure, but this and other similar careless statements of facts mar an otherwise good and useful volume, and call for a thorough revision for the second edition.

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.]

Electrical Notation.

SIR JOSEPH LARMOR's letter in NATURE of January 21 (p. 561) reminds me that I have long wished to protest against the misuse of alphabetical symbols to designate the names of units. The word ohm, for instance, ought not to be abbreviated to ; and the apparently authoritative suggestion now made that other names shall be written in the same sort of unreadable and worrying shorthand is essentially, though not superficially, illiterate as well as utterly unmathematical.

The naming of units has been conspicuously useful; the consumption of much-needed and already overworked symbols as substitutes for names is a wasteful practice which should be resisted among physicists, and be only tolerated in microscopy for purely biological use.

OLIVER LOdge.

University of Birmingham, January 23.

Mendelism in the Seventeenth Century. THE Mendelian revival of breeding has brought to light many interesting facts concerning the inheritance of coat-colour in rabbits. From the work of Hurst, Castle, Punnett, and others, it is now known that when the

66

wild "grey or agouti " rabbit is mated with white, black, or blue" specimens, the offspring produced all display the colour of their wild parent. Although this is doubtless well known at the present day, it is, I believe, not generally known that these facts had been ascertained by rabbit-fanciers in Holland in the seventeenth century, and were put on record by the illustrious Leeuwenhoek in 1683.

In a letter from Leeuwenhoek to the Royal Society, addressed to Sir Christopher Wren, and dated July 26, 1683, the following remarkable passage occurs :

Multi nostratium civium alunt cuniculos, cum ad voluptatem, tum ob lucrum: suntque hi cuniculi plerumque magni atque albi, auribus praelongis donati, quod pulchritudinis loco ducunt. Ut vero hi cuniculi in lucem edant pullos grisei sive cinerei coloris, qualis est sylvestrium, utque pro his possint verno tempore vendi, foemellae albae marem griseum ac sylvestrem ex tumulis arenarum petitum, ubi grisei coloris sunt, sociant: atque tales masculos intense griseos committunt non tantum cum

omnes

albis, sed & versicoloribus, nigris, caeruleis foemellis: Ex quibus tamen quicquid procreatur, colorem patris refert; ut nunquam etiam observatus sit ullus ex tali jugatione productus cuniculus, qui fuerit capillo albo, aut alio quam griseo. Praeterea tales nunquam attingunt magnitudinem matris, neque aures acquirunt praelongas, neque pro matris natura plane cicurantur ac mansuefiunt, sed retinent semper aliquid ferocioris ferinaeque naturae ac indolis."

The letter will be found in the so-called “ Opera Omnia" of Leeuwenhoek (Lugd. Batav., 4 vols., 1722). Owing to the confusing arrangement and pagination in this work-which consists of a number of separate sections, published at different dates, each with its own pagination-it is not easy to give an exact reference to a particular passage. In the copy of the Opera Omnia which I have consulted, the letter occurs on p. 49 (first pagination) of vol i. ("Anatomia et Contemplationes"), under the title, "De generatione Ranarum," etc. The passage in question begins at the foot of the following p. 53.

46

I may add that the letter is not to be found in Samuel Hoole's English edition of Leeuwenhoek's Select Works" (London, 2 vols., 1798, 1807). This translator expurgated all Leeuwenhoek's letters dealing with spermatozoa. He calls them "Disquisitions of a peculiar kind, which to many Readers might be offensive."

Feeling some doubt as to the colour or marking which versicolor " is intended to denote, I compared the Latin letter with an English version which was published under the title, "An Abstract of a Letter from Mr. Anthony Leeuwenhoeck of Delft about Generation by an Animalcule of the Male Seed, etc.," in the Philosophical Transactions of the Royal Society, vol. xiii. (xii.), p. 347, 1683. Both Latin and English versions are translations from the Dutch for Leeuwenhoek could write no language but his own. In the English version, which is somewhat differently worded from the Latin, the words "versicoloribus, nigris, caeruleis" are rendered "Blew, Black, and Pyed." "Versicolor" evidently denotes some kind of piebald marking; though it probably does not meanas one might perhaps conclude the modern "Dutch" pattern. This, Prof. Punnett tells me, is of comparatively recent introduction, and has superseded an earlier or "original Dutch" marking which "has less white and has practically dropped out of the fancy." It is clear from Leeuwenhoek's words that the Dutch rabbit-fanciers had, as early as 1683, discovered that the offspring produced by mating wild "grey buck rabbits with tame long-eared white, black, blue, or piebald does, are always exclusively grey in colour; and that they are sufficiently like the wild rabbit in other respects also for them to be marketable as such.

Leeuwenhoek's statement that the hybrids produced by crossing piebald with wild rabbits are invariably grey " in colour-without any white-seems open to question. Recent experiments have not yet solved the problems of the inheritance of pied patterns in rabbits. Prof. Punnett, who has been studying the matter for some years, tells me that when wild rabbits are crossed with modern Dutch, "the F, animals may be, though rarely, completely self-coloured. Generally they have a little white. The amount of this varies. but never approaches the amount found in the Dutch." The statement that the progeny of long-eared tame doe-rabbits and wild males never possess such long ears as their mothers, appears to have been confirmed by Castle. "He crossed the long-eared lop rabbit with ordinary short-eared individuals. F, had ears of intermediate length" (Bateson, "Mendel's Principles of Heredity," 1909, p. 251). I do not know of any confirmation or contradiction of Leeuwenhoek's final

assertion that the offspring of wild males and tame females tend to manifest the wild temper of their fathers.

It seems remarkable that nobody-so far as I am aware has hitherto directed attention to the passage which I have quoted above. It occurs incidentally in a letter which described such novelties as the spermatozoa and red blood-corpuscles of the frog, and the ciliate Protozoa parasitic in the frog's intestine. But it is perhaps even more remarkable that neither Leeuwenhoek at the time, nor anybody else for some two hundred years subsequently, perceived the importance of such observations as the rabbit-fanciers of Holland had made. Leeuwenhoek was, of course, an "animalculist": and he cites the case of the rabbits to confute "non nemo Doctorum "-evidently an "ovist "-and to "bring a sufficient proof of the fruits coming from the Male seed, and the females only contributing to the nourishment and growth of it." Leeuwenhoek's remarks evidently do not constitute the earliest known reference to rabbit breeding. For Darwin ("Animals and Plants," chapter iv.) gives earlier references to Gervaise Markham (1631), and Aldrovandi (1637), which show that several kinds of rabbit were already kept and bred at the beginning of the seventeenth century. Nevertheless, the passage which I have quoted above is, perhaps, the earliest exact account-based upon experiment-of the inheritance of any character in any animal or plant; and as such I think it is worthy of record.

I am indebted to my friend, Prof. R. C. Punnett, F.R.S., for information on certain matters mentioned in this letter; and I would refer the reader interested in the subject to his important paper, "Inheritance of Coat-Colour in Rabbits," published in the Journal of Genetics, vol. ii., No. 3, 1913, for further facts. CLIFFORD DOBELL. Imperial College of Science, South Kensington, London, S.W., January 15.

Books for Belgian Students.

or

WE are gradually building up a little Belgian University here for students who, for one reason another, cannot go to the front, and for professors who are past the age of serving. Altogether we have between one hundred and two hundred students, and some fifteen to twenty professors.

Last term we were able to establish effective teaching in four faculties, and this term we have increased the number to six. In the faculty of medicine we are in need of copies of some standard text-book on human anatomy-preferably Gray's.

This University has already found several thousand pounds to support our guests, and will have to find several thousands more to keep things going until next June. Consequently we have to husband our resources very carefully, and cannot afford to purchase such expensive text-books as Gray's "Human Anatomy."

It may be that your readers have copies of this work lying unused on their shelves. If this is so, I should be grateful if they would send them to me for the use of these students. At present ten or a dozen copies would suffice. A. E. SHIPLEY. Christ's College Lodge, Cambridge, January 25.

An Unexplained Laboratory Explosion.

I SHALL be glad if any of your readers can give me an explanation of the following occurrence.

Owing to the fact that we are somewhat out of the way here, and, in consequence, fresh bleaching

powder is difficult to obtain, I have found it necessary, when demonstrating the formation of chloroform, to find some method other than the usual treatment of alcohol with bleaching powder.

With this object, a few days ago I prepared a mixture of 60 grams of slaked lime with 400 c.c. of cold water and 40 c.c. of alcohol. The mixture was placed in a 2000 c.c. flask, through the cork of which a long tube conducted chlorine to the bottom of the liquid. Through the cork also went another short tube connected to a condenser.

Chlorine had been passing into the liquid fairly quickly for about twenty minutes, and the contents of the flask had warmed up to perhaps 50° C., when a slight smell of chlorine became evident at the end of the condenser, together with a small amount of white fumes; but inside the big flask, except for the slight rise of temperature, there was no evidence of chemical action. Suddenly, with no warning whatever, the whole apparatus blew up; I might almost say detonated, as there was not a piece bigger than a sixpence left, either of the flask, the condenser, or the small flask put to catch the distillate when it should arrive.

Owing perhaps to the violence of the explosion, I got off with a few scratches on my face. My clothes were cut by pieces of glass, however, and the fragments were scattered for at least six yards all round. There was no odour, either of chloroform or anything else, apparent; only that of the chlorine from the generating flask, which, curiously enough, had escaped injury. The whole delivery tube was intact, and also the exit tube from the big flask, the neck of which, with the cork, was left sticking in the clamp, so that I was able to be sure that the trouble was not due to a blocking up of the exit. W. F. A. ERMEN.

O. Granbery, Juiz de Fóra, Minas,
December 11, 1914.