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defined above. The question cannot be discussed with a male quagga, when compared with the results on the present. occasion, but it is well to bear in of Prof. Cossar Ewart's researches, prepare us for the mind that however completely the causes of evolu- belief that many a general impression which has been tion in the past may evade our attempts at demon- produced as evidence will collapse when it has become strative proof, the history of evolution is a subject the subject of searching and critical investigation. which can be brought to the test. For many years it In the preface the author speaks with some diffihas seemed to the writer that palæontology can settle dence of the prominence given to his own researches. decisively whether evolution has been continuous or Investigations such as those into the effect upon olldiscontinuous. Those who desire to bring conclusive spring of the relative freshness or staleness of the evidence to bear upon this important controversy parental germ-cells would, in any circumstances, be would do well to follow the example of Prof. W. B. an unfortunate omission from a book on variation. Scott, of Princeton, who told us at Cambridge that They are, moreover, described in the publications of he was “just crazy” over the fossil mammals of scientific societies not always freely accessible to the Patagonia.

general reader. For another reason also the book In the last chapter, on adaptive variations, the would have suffered if these researches had been treated author would have done well to place in the forefront less fully. When the author of a general work is not the warning that a superficially apparent example “ of altogether wanting in the sense of fitness and propordirect adaptation to surroundings in the ordinary tion, the account of his own contributions to science acceptation of the term ... may be the calling up, will probably be the salt of his book. These subjects in response to one of two stimuli, of one of two groups stirred his own enthusiasm for research, and in writing of characters long since acquired by the plant proto- of them he is likely to stir the enthusiasm of others. plasm.” The principle contained in these words

E. B. P. should be prominently before the mind of the naturalist who attempts to investigate the response of an organism to its environment. He should remember

MATHEMATICAL THEORY OF ECLIPSES. that the species which he investigates are “heirs of The Mathematical Theory of Eclipses, according to all the ages," thoroughly inured to experimental re- Chauvenet's Transformation of Bessel's Method. search, past masters in the art of meeting by adaptive Explained and illustrated by Roberdeau Buchanan, response the infinite variety of stimulus provided by

S.B. Pp. +247. (Philadelphia and London : the environment. If he remember this he will always J. B. Lippincott Co., 1904.) Price 315. net. be on his guard against a too hasty interpretation WHEN a practical man devotes himself to the


of The discussion of the question, are acquired any specialised subject on which he has been engaged characters inherited ? (pp. 351 et seq.) is a particularly for many years, the result is likely to be satisfactory. interesting and suggestive introduction to the subject. There is always the chance that the prolonged study A few well chosen examples of the evidence chiefly of one particular subject has had the effect of unduly appealed to in support of such transmission exalting its importance, with the consequent loss of followed by a brief but well balanced discussion. The a proper perspective, and when one sees a compara. author supports the conclusion that the soma, and tively narrow branch of astronomical inquiry, like through the soma the environment, exert a chemical eclipses, occupying a rather ponderous volume, he may influence upon the germ-cells, and he makes effective be led to think that the subject has been indiscreetly use of the “ internal secretions ” which have marked expanded. We therefore hasten to say that there is an epoch in physiological research.

no evidence of disproportionate treatment in Mr. Several examples, generally believed to supply | Buchanan's book. He himself has been employed for evidence of the “cumulative action of conditions of twenty-three years in the office of the “ American life” (pp. 352 et seq.), would be more satisfactory Ephemeris and Nautical Almanac," and during that and convincing they were re-investigated as a piece time has been responsible for the accurate preparation of special research. Too often they bear the impress of the necessary information connected with eclipse of 'an off-hand opinion without any secure foundation prediction. His practical acquaintance with the subupon specially directed inquiry. Thus, in the trans-ject eminently fits him for the task he has undertaken, port of adult sheep or dogs to a different climate, it and his book is a success. The moon's nodes have may be expected that leśś change will be manifest in made more than one complete revolution since he the hairy covering of the parent than in that of the off- began his work, and an entire series of eclipses has spring which has been born and passed the whole of its revealed to him their peculiarities and oddities. life in the new conditions. Thus the appearance, but The theory of eclipses has been well explained by by no meanis necessarily the reality, of an accumulated various astronomers, and practical rules given by effect may be produced. In order to test the hypo

Hallaschka, in his “ Elementa Eclipsium," thesis of accumulation, it would be necessary to neglect following the method of orthographic projection, has the generation which has been subjected to two very worked out an example in full. Woolhouse, in the different environments and to determine quantitatively appendix to the “ Nautical Almanac" for 1836, not with all possible accuracy the characters of those only discussed the subject with great fulness, but which follow. The often repeated statements about gave practical rules for the determination of the the telegonic effect of mating “ Lord Moreton's mare phenomena, which for many years were followed in





the preparation of the English ephemeris, and perhaps Downing, quoted by the author, we gather that the are so still. Bessel gave a more thoroughly con- occultation diameter of the moon, as used in the presecutive discussion, which Chauvenet followed in his paration of the English “ Nautical Almanac," differs treatise, and this last forms the basis of Mr. 2".36 from that employed in eclipse calculations. But Buchanan's work. The practical part of the arrange- we find a little difficulty in following the author in ment does not seem to be easily systematised. A his reference to authorities. In the matter of lunar computer finds some difficulty in translating the parallax, Adams is not quoted, and Lardner's “ Handformulæ into numbers. There are to the uninitiated book of Astronomy,” or Proctor on " The Moon," continual ambiguities about the quadrants; and the can scarcely be considered original and trustworthy manner in which angles are to be reckoned is fre

W. E. P. quently a stumbling block to the unwary. Perhaps these little difficulties are more noticeable in Woolhouse's method than in Bessel's, but it is with the view

ENGLISH FIELD-BOTANY. of limiting these troubles and of giving a convenient arrangement to the whole of the work that Mr. Flora of Hampshire, including the Isle of Wight. By Buchanan has written his book. In his time he must

Frederick Townsend, M.A., F.L.S. Second edition. have met with all the difficulties with which a young

Pp. xxxviii +658. (London : Lovell Reeve and Co., computer has to contend, and must have removed these Ltd., 1904.) Price 215. net. out of the path of many. Knowing these pitfalls, he has done his best to get rid of them by suitable explan

the British flora has not yet received the careful ations, and probably with success. But those who critical attention which has been lavished on Conhave conducted pupils through carefully worked tinental floras. To a certain extent this is doubtless examples know only too well that a fresh set of diffi

We have no manual that for thoroughness of culties is apt to reappear with a new case.

treatment and wealth of reserence to original descripThe author has divided his book into two parts. tions and type-specimens can compare with Rouy and In the first he treats of solar eclipses and the method Foucault's “ Flore de France"; at the same time there of deriving the various curves which are necessary for is an abundance of valuable information scattered the exhibition of the whole circumstances of the through our numerous natural history journals only phenomenon on a map. Here we get the north and waiting for some energetic and widely experienced south limits of total and partial eclipses, the position systematist to collate and bring together in a really where the eclipse begins and ends with the sun in the satisfactory British flora. There are several botanists horizon, and one can follow the method by which eminently fitted for such an undertaking, and it is are drawn those weird curves on the eclipse maps that urgently to be desired that one or more of them should accompany every nautical ephemeris. By way of take the matter in hand. Meanwhile, our numerous adding a little lightness to a rather dreary subject, we and rapidly accumulating county floras are paving the may notice some curiosities the explanation of which way to a complete botanical survey of the British is not very readily seen without the assistance of a Isles. competent guide, such as the occurrence of a north In Mr. Townsend's “ Flora of Hampshire and the limiting curve of totality falling south of the south Isle of Wight” we have one of the best books of its limiting curve. Ingenuity might construct class, and the work and careful attention expended further troublesome problems of this nature when the upon its production must have been very considerable. clue is furnished, and one can imagine an examiner | The volume opens with a chapter on topography and exulting over the discovery of such oddities, affording climate. This is followed by an account of the geoas they do opportunity for worrying unhappy candi- | logical structure of the district, including a summary dates who fall into his hands.

of Mr. Clement Reid's researches on the fossil seeds In the second part of the book we have detailed of the Stone and Silchester beds of the newer Tertiary the method of computing the circumstances of lunar formation. In his list it is particularly interesting to eclipses, occultations of stars by the moon, and of the notice the names of several plants usually regarded transits of Venus and Mercury. These are practically as weeds of cultivation, or as colonists, such as particular cases of the same problem as that treated Brassica alba, Boiss., Thlaspi arvense, L., Linum in the first part, simplified by certain conditions. In usitatissimum, Linn., and also damson and plum. the case of the lunar eclipse, the absolute position of The now generally approved method of dividing a the moon and shadow are independent of the position of district into botanical areas according to its riverthe observer on the earth, and therefore the effects of systems is here in the main followed, and a useful map parallax can be treated much more simply.

We of the county is appended. Turning to the systematic notice that the semi-diameter of the shadow is in- section-by far the larger portion of the book--so creased by the fiftieth part of its amount, in preference many points call for attention that it is quite impossible to the older estimate of 1/60, but the whole question within the limits of a short notice to mention more of semi-diameters is a troublesome one, which will than a few of them. In the section devoted to son have to be treated with great rigour. The Ranunculus, what appears to be a satisfactory occultation semi-diameter is not altogether satis- | account of the forms of R. acris is given; this will be factory, and some international convention is needed appreciated by many collectors. The name Nymphaea to secure uniformity. From a

letter from Dr. alba, Linn., is retained instead of (astalia speciosa,





Salisb., which found favour in the eyes of the editors of and working of small destructors,: The aim has been the London Catalogue (ninth edition). Viola to make clear the fact that high temperature working calcaria, Bab., appears as var. B of V. hirta, Linn., is as vital in the small as in the large destructor, though the author admits an inclination to regard it In an introductory chapter Mr. Goodrich lays down as a starved or stunted form rather than a variety. No the principles which must be observed in the design mention is made of V. calcaria, Gregory, which has of small destructors, and he points out that it is been cultivated, and appears to be a good species. possible to operate at a low working cost such de

V. canina, Linn., is given as synonymous with structors when built on modern lines. The weak points V. flavicornis, Sm., non Forster, while V. ericetorum, in the design of the earlier forms were precisely those Schrader, appears as a hybrid canina x lactea. All which were found in the early forms of large municipal botanists will not find themselves in agreement with destructors, namely, low temperature system of workMr. Townsend upon this point, for V. ericetorum is ing, slow combustion, and inadequate and unsatis sometimes abundant where V. lactea is extremely factory methods of feeding the refuse into the cells;

Perhaps it may be hoped that cultivation will these difficulties, however, have all been overcome, and settle the question, especially if it be found that hybrid at the present day small destructors for use in institu. violas obey Mendel's law of segregation.

tions such as isolation hospitals, hotels, &c., can be The list of Rubi brings the number up to eighty-five, obtained as satisfactory in every respect as the large making the county, with one exception, the richest ones now so commonly employed. On account of the in brambles of any in the British Isles. Some useful unpleasant substances which have to be dealt with in notes on the genus Erythræa are given, and the variety | many of these institutional destructors, they are often sphaerocephala, Towns., of E. capitata, Willd., is neglected, and proper supervision over them is not beautifully figured; the author now considers that the maintained; this leads to the refuse being improperly plant does not merit a varietal name.

fed into the destructor; in a good modern type there Among the Monocotyledons, the Rev. E. F. Linton's is no risk of this misuse, as it is impossible to feed Orchis ericetorum is fully described. It appears to be the destructor in any other way than that originally a well marked plant, and the fact that it grows only provided by the designer. on heaths while the chalk plant is typical 0. maculata A number of typical destructors suitable for such cannot be said to militate against its claim to specific institutions are described and illustrated, the drawings rank in view of the parallel case of distribution of the being fairly complete. In thinly populated districts two plants included under the Valeriana it is often advisable to have a portable destructor, and officinalis, Linn. But here again there may be great two very successful ones of this type, namely, a virtue in cultivation. It is satisfactory to find the Horsfall and a Meldrum, are described. Such porttruth told about Ruscus aculeatus. The plant with able destructors would be invaluable during campaigns staminate flowers has narrower cladodes than the and in our home training-camps. How dangerous pistillate plant, and there is no evidence for a narrow- the waste from a large camp may become to health leaved and a broad-leaved variety.

was vividly shown during the inquiry by the Royal In an appendix appear notes on several plants, Commission into the war in South Africa. Many of amongst which are Stellaria umbrosa, Opiz, and the medical witnesses expressed the opinion that S. media, Linn. (both of which are fully diagnosed), | hundreds of lives might have been saved had the Prunus spinosa, Linn., P. fruticans, Weihe, P. necessary steps been taken to destroy camp refuse insititia, Linn., and P. domestica, Linn. An account properly and to supervise thoroughly the sanitary conof Murbeck's arrangement of the gentians is given, dition of camps. In America, which, strangely and all the forms of Euphrasia and Salicornia noted enough, has lagged behind in the adoption of muni. in the county are described. So much matter of cipal destructors, there has been a considerable degeneral interest is brought together that no field velopment in the utilisation of the smaller forms, both botanist, be he a native of the district or a worker in

for hospitals and for hotels. The latter portion of the any other part of the country, can afford to neglect book treats of the disposal of trade refuse, and the this volume.

author points out how valuable from the point of view of generation of power this trade refuse often is. Such

trade refuse can only be burnt in boilers specially de SANITARY ENGINEERING.

signed for fuel of low calorific power, and where the

boilers are properly designed there is no difficulty in Small Destructors for Institutional and Trade Waste.

utilising it. A number of different types of furnaces By W. Francis Goodrich. Pp. 127. (London :

and boilers suitable for use with trade waste are deArchibald Constable and Co., Ltd., 1904.) Price 4s.

scribed and illustrated in these chapters.

The last few pages of the book are devoted to a R. GOODRICH'S book on “Refuse Disposal discussion as to the advantages of disposing of car

and Power Production,” which dealt with the cases of diseased and condemned beasts by means of problems arising in the disposal of civic waste, was suitably designed destructors. The book will be recently reviewed in these columns (May 12, 1904, vol. found, like Mr. Goodrich's other books upon this im1xx. p. 25); in the present volume the same author portant branch of sanitary engineering, extremely treats of the equally important subject of the disposal of valuable by all who are engaged in dealing with the institutional and trade refuse, that is, with the design disposal of solid refuse.

T. H. B.





with the cooperation of others interested in the growth La Statique chimique basée sur les deux Principes and utilisation of timber in every part of the globe. fondamentaux de la Thermodynamique. By E.

In all 247 different species are described, even to the Ariés. Pp. viii +251. (Paris : A. Hermann, 1904.) minutest detail. In each case the specific name and Die heterogenen Gleichgewichte vom Standpunkte der confusion, the synonyms have also been added. Then Phasenlehre. Zweites Heft, erster Teil. By H. W.

comes a list of the alternative names, or what we

It is a well known Bakhuis Roozeboom. Pp. xii + 467. (Brunswick : might call the common names. F. Vieweg and Son, 1904.) Price 12.50 marks.

fact that frequently one and the same kind of timber The two volumes under review are concerned with receives two different names, whereas two totally the application of thermodynamics to the problems of

different species may be known by the same common general chemistry, but are yet so different in material

name. The vernacular names in foreign languages, and in treatment that few points of resemblance may also been quoted. Following this comes a paragraph

so far as they are not to be found in dictionaries, have be found between them.

In the book by Lieut.-Colonel Ariès the mathe- dealing with physical characters, &c., such as recorded matical derivation of the laws of equilibrium from dry weight, hardness, taste, combustion, character of the fundamental principles of thermodynamics are

ash constituents, &c. The grain and bark are next stated in the most abstract and general form with just described. The following paragraph deals with the sufficient exemplification to indicate the bearing of the

uses to which the timber may be put. The colour is deductions on the practical work of physical chemistry. anatomical characters, as seen in transverse and longi

also given as means of identification, and the The author uses as characteristic function the thermodynamic potential at constant pressure, and it may be tudinal sections, are fully described. said in a word that his deductions are as simple and ing and authenticating the vast amount of information

The author seems to have spared no pains in collectconcise as the case will allow, the introduction of useless conceptions and formulæ being scrupulously

and details necessary for the above purpose. A very avoided. One noteworthy feature which might with valuable feature of the book are the illustrations, advantage be imitated in other works on thermo- numbering 183 photomicrographs, which represent all dynamics applied to chemistry is the postponement of illustration serves for more than one genus.

the genera mentioned in the text, except where a single

In most the discussion of the perfect gas to a point in the last

cases third of the volume. The student is only too apt in

the photographs are taken from transverse dealing with the involved formulæ of certain cases of sections, though in many cases longitudinal sections chemical equilibrium to introduce unconsciously into

are also given. It is stated that the scale of magnifihis equations some result which has its origin in a

cation is three times the actual size, and is designed consideration of perfect gases, thereby obtaining a

to show the appearance of a transverse section as seen simple result apparently general, but in reality not so.

by means of an ordinary hand lens. For those deThe temptation to do this is greatly lessened by the siring further general information about wood a very simplification of the perfect gas being delayed Also two appendices are added, which respectively

useful bibliography is given at the end of the book. until the general formulæ are well developed.

The book is well and clearly written, and those interested

describe the method and apparatus for measuring the in mathematical chemistry will be thankful for this absorption of water by a given area on any surface of

amount of resistance in timber to impact and the lucid exposition of the subject. The first part of Prof. Roozeboom's book has already

a piece of wood. been noticed in NATURE. It dealt with the equilibria

At the beginning of the book a very interesting of systems of one component. The present volume chapter, entitled “ Practical Hints,” is included, which deals with the equilibria of binary systems, though

we are sure will be read with much interest and profit such is the wealth of material that it has been found by all those who work with wood. The index is a necessary to reserve the discussion of many systems

very complete one, and will render the book invaluable presenting special features for a subsequent volume.

as a ready work of reference. In contradistinction to the work of Colonel Ariès, there Verhandlungen der deutschen zoologischen Gesellis scarcely a mathematical formula to be found in Prof. schaft, for 1904.

Pp. 252 ; illustrated. (Leipzig : Roozeboom's treatise; the graphic method is used to Engelmann.) Price uis. net. the practical exclusion of others. In the present part | This valuable publication contains the papers read at there are 150 diagrams, chiefly of curves the co- the twenty-fourth annual meeting of the society, held ordinates of which are pressure, volume, temperature, at Tübingen on May 24-26, 1904. The congress was and composition in some combination. As in the first opened by an address from Prof. Spengel, in which the part, the various equilibria are carefully classified society was congratulated on the good work it conaccording to the nature of the phases involved, and tinued to produce, and especially on recent investicach class is discussed in detail with the most pains- gations on the structure of the Protozoa and on the taking completeness, and with full reference to the relations of the nucleus to the general mass of proto original sources of the experimental work used in illus- plasm. To Prof. Blochmann was assigned the tration. In general terms the volume may be said to pleasant task of welcoming the society to Tübingen. deal with simple solutions, and no one whose interest | The published papers are sixteen in number, in addition lies in this direction can afford to dispense with the to which were numerous exhibits and demonstrations. aid of such a valuable guide to the work already Most of the former are of an extremely technical accomplished, and to the theory of the practical work character, and to a large extent.interesting chiefly to still to be performed.

J. W. specialists. Among them we may refer to Prof. A. The Timbers of Commerce and their identification. structure of the light-organs of the bony fishes, more

Brauer's account of recent investigations into the By H. Stone.' Pp. xxviii +311. . (London: William especially of the deep-sea forms, in which the question Rider and Son, Ltd., 1904.) Price 75. 6d. net.

of the relation of these structures to the lateral line This work is sure to meet with a cordial reception system is discussed at considerable length. Dr. von and to be welcomed by all branches of the timber trade. Buttel-Reepen's article on the mode in which the larvæ The information contained in its pages is such that of the honey-bee are made to assume a particular sex only an enthusiast and expert could bring together is also one of considerable importance. In the course of a discussion on the zoological system as commonly

LETTERS TO THE EDITOR. taught, Prof. H. E. Ziegler emphasises the view that (The Editor does not hold himself responsible for opinions the rhizopod and flagellate animalcules, together with

expressed by his correspondents. Neither cari he undertake the Sporozoa, form an allied assemblage, while the to return, or to correspond with the writers of, rejected ciliated animalcules, both as regards the nature of manuscripts intended for this or any other part of NATURE. the nucleus and the mode of reproduction, are No notice is taken of anonymous communications.) altogether different. In a fourth important communication Dr. Bresslau amplifies and illustrates his

Average Number of Kinsfolk in Each Degree." discovery that the marsupium of the marsupials, in May I ask you to insert yet another brief communication place of being a simple organ, is really formed by the

on the above subject, because private correspondence shows amalgamation of a number of small pouches. These

that paradoxical opinions are not yet wholly dispelled? pouchlets, which at first form solid ring-like growths The clearest way of expressing statistical problems is the of the epidermis, soon begin to degenerate, and are

familiar method of black and white balls, which I will now

adopt. merged in the wall of the marsupium.

R. L.

Plunge both hands into a dark bag partly filled with black The Optical Dictionary. Edited by Charles Hyatt- and white balls, equal in number, and well mixed, Grasp

Woolf, F.R.P.S. Pp. x+77. (London : The Guten- a handful in the right hand, to represent a family of boys berg Press.) Price 4s. net.

and girls. Out of this unseen handful extract one ball, still This is an optical and ophthalmological glossary of

unseen, with the left hand. There will be on the average English terms, symbols, and abbreviations, together

of many similar experiments, as many white as black balls,

both in the original and in the residual handful, because with the English equivalents of some French and

the extracted ball will be as often white as black. Using German terms arranged alphabetically. The mean

my previous notation, let the number of balls in the original ings are, as a rule, very clearly given, and the book handful be ad. Consequently the number in the residual should prove of use to students (especially medical handful will be ad-1, and the average number in it either students) who suddenly come upon an unfamiliar term of white or of black balls will be half as many, or 4-5. in the course of their general reading. Of course, it It makes no difference to the average result whether the must be understood that it is practically impossible hitherto unseen ball in the left hand proves to be white or to explain properly any scientific term in a line or two, black. In other words, it makes no difference in the and this is all that is attempted; the meanings given estimate of the average number of sisters or of brothers must therefore in most cases be somewhat unsatis whether the individual from whom they are reckoned be a factory. But the book will doubtless succeed in its boy or a girl; it is in both cases d-. The reckoning may

proceed from one member of each family taken at random, aim, especially in the translation of foreign terms.

or from all its members taken in turn; the resultant average As regards accuracy—the sine quâ non of a dictionary

comes out the same. --we only notice a very few actual errors, e.g. This, briefly, is my problem. Francis GALTON. dioptrically does not mean by reflection, and in the definition of numerical aperture the words refractive index of the medium in which the object is immersed

On the State in which Helium Exists in Minerals. scarcely indicate that the medium must extend into IN 1898 I published in the Proceedings of the Royal contact with the objective. Underlant is apparently Society the results of some experiments on the evolution of a misprint for undulant, and one-third of p. 70 has

gases from minerals on heating them. I succeeded in got into its wrong place.

proving that the hydrogen and carbon monoxide in the gases But these are not very important blemishes, and we

could be accounted for quantitatively by the reduction of cordially recommend the book to those whom it may

water vapour and carbon dioxide by ferrous oxide, or by

similar substances, and that, except in cases in which concern.

cavities could be proved to exist, the evolution of a gas Practical Professional Photography, Vols. i. and ii. from a mineral implied chemical change at the moment of

By C. H. Hewitt. Pp. 126 and 114. (London : heating. In the cases in which helium was evolved on heat

Iliffe and Sons, Ltd., 1904.) Price is. net each. ing a mineral, I pointed out that by the action of beat it is These two volumes form a very useful addition to the possible to obtain only half the helium, though the evolution Photography bookshelf series, of which they form

of this gas never really ceases, but only becomes very slow,

This I took to be evidence of the existence of a chemical Nos. 17 and 18. Although the author does not profess compound of helium with some constituent of the mineral. to go into any great detail, he gives an excellent

Recently (Trans. Roy. Dublin Soc., 1904) Mr. Moss has account of the necessary requirements of the pro- shown that by grinding pitchblende in vacuo helium is fessional photographer, from the choice of business

evolved, and considers this result as certain evidence of the premises, the handling of customers, book-keeping, existence of the gas in the free state in cavities. Since, &c., down to the packing up of the finished pictures however, helium is evolved, though slowly, from the crushed and their dispatch. The chapters on portraiture, com- mineral at a temperature not above 300° C., the liberation position, and lighting are especially satisfactory, and of the gas in Mr. Moss's experiment may be attributed to many a valuable hint is contained therein.

local heating set up in the process of grinding. A great number of illustrations accompany the text,

In view of recent discoveries it appears to me that both and serve the useful purpose of illustrating the author's

of us have been on the wrong track in looking for an remarks on many lines of work.

explanation of the phenomenon. As Sir William Ramsay

and Mr. Soddy have shown, the presence of helium in the Solutions of the Exercises in Godfrey and Siddons's minerals may have resulted from the decomposition of radio

Elementary Geometry. By E. A. Price. Pp. 172. active matter, formerly present in them. Recently Dr. (Cambridge: The University Press, 1904.) Price Jaquerod, of Geneva (Comptes rendus, 1904, No. 20, p. 789). 55. net.

has found that when helium is heated in a quartz bulb to This book will be found very useful to all, both pupils

a temperature above 500° C. the gas passes out through the and teachers, who use the well known work of Messrs. quartz with a velocity which increases with the temperature. Godfrey and Siddons. The solutions, 1836 in number,

At 1100°, in a comparatively short time the pressure in contain not only the deductive, but the drawing Hydrogen appeared to behave similarly,

the bulb fell considerably below that of the atmosphere. exercises, the figures being all such as the pupil is required to construct. We cannot refrain from plead-stances of the nature of the minerals we are considering,

This experiment shows that quartz, and probably subing for a better figure of a hyperbola than that given though impermeable to helium at low temperatures, become on p. 143, which a trained eye rejects at once, although permeable at moderately high temperatures, and furnishes it is not essential to the pupil's work.

us with a solution of the second part of our problem.

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