throughout the country; in promoting technical education; in reference to national musical training; in regard to postal reforms; in the institution of public examinations for various purposes, and numerous other subjects of public interest.

In later years the "Cantor" and other lectures by eminent scientific men on all manner of subjects have more and more become one of the chief elements of the society's well-known usefulness.

This is made evident by the author, who also gives accounts of other of the society's manifold activities in various directions, which cannot here be mentioned for want of space.

THE

HE author of this book is professor of physics in the Macdonald College, an affiliated college of the McGill University, Montreal, where a school of household science is one of the branches of the institution, and it is for students of household science that the book is written. It presents the subject of physics in close relation to its domestic applications, and abounds in illustrations and examples of household appliances and processes. It should be of great use to science teachers, especially those who have to teach girls, in reminding them of the range of familiar things and topics of physical interest that lie in the home environment, and that often lie unheeded and unexplained.

The suitability of the book for students themselves is, perhaps, more open to discussion, and it is more than likely that it will come under the censure of teachers who are wedded to the conventional form of text-book. The chief ground of attack would no doubt be that so far as the general principles of physical science are concerned, the elucidation is cramped and obscured by the weight of illustrations of their practical application. To treat the subjects of mechanics, heat, electricity and magnetism, light and sound and their applications in three hundred pages has led to a certain breathlessness of style, and some topics are treated very vaguely.

The gaps in the knowledge of those in control of the household that are the most conspicuous and seem to call most loudly for repair, do not relate so much to the design and principles of construction of appliances, as to the conduct

of operations. An increased apprehension of the application of the lever principle or of the construction and modus operandi of an electric bell is all to the good, but it is not to be compared with a real live knowledge of the laws of heat and the capability of thinking and acting within them in the great field of household operations to which they apply. It is extraordinary to see the woodenness with which a woman armed with the conventional "heat" of the school or college textbook will face simple problems of heating or cooling as they arise in the household. This defect is not to be repaired merely by a rational account of the principles on which heating appliances are constructed. To instil real activity of mind it is necessary to teach in terms of problems with a wide range of experimental exercises.

For the reasons indicated above, it is fair to say that the value of Prof. Lynde's book to students must depend very largely on the laboratory work that accompanies it, and on the constant raising of questions and corollaries by the teacher. This, however, is true of most textbooks, and it must not lead us to undervalue one that has so large an element of originality and is so likely to be useful. A. S.

(1) WHA

THAT fox-hunting is to England, pigsticking is to India, with the difference that the latter has that spice of personal danger from attacks on the part of the quarry which, to the regret of many sportsmen, is entirely lacking in the former. Both, too, have nowadays this in common, namely, that in their headquarters they depend to a greater or less degree on protection for their quarry—a fact which may come as a surprise to those unacquainted with India at the present day, and the great diminution in the numbers of its big game which has taken place in many districts. The headquarters of pig-sticking are the "khadirs," or river-valleys, of the Ganges and Jumna in the respective districts of Meerut and Muttra; and to old Anglo-Indians who have ridden or shot in the khadir, Major Wardrop's gossipy book will come as a delightful reminiscence of bygone days. To the newcomer in India it will serve as an incentive to rival the deeds of his predecessors in one of the most noble and exciting of all field-sports.

How well qualified is the author (aided by contributions from other hog-hunters) for his task may be inferred from the statement that he has been present, to the best of his belief, at the death of between seven hundred and eight hundred boars.

To stay-at-home people such numbers. may savour somewhat of exaggeration, but any such misgivings may be dispelled by reference to the final chapter of the book, where he will learn that the average annual bag of the Muttra tent-club alone is 210 head.

Major Wardrop gives his readers a glimpse of early pig-sticking by recalling the almost forgotten fact that for the first quarter of last century the universal weapon was the long throwing spear, and that the modern short "jobbing" spear did not come into use until 1830. In the penultimate chapter he discusses the paraphernalia and technique of the sport. For the contents of the intermediate chapters the reader must be referred to the book itself, which he will probably not leave until he has read it from cover to cover.

(2) An equally delightful volume is the second on our list, although it has to be confessed that its contents include more "philandering" than "fishing"; but since it teems with anecdotes which can scarcely fail to raise a hearty laugh, its appearance in these troublous times should be very welcome. Like the first, this volume will prove of interest to Anglo-Indians, as it comtains a chapter of mahsir-fishing, coupled with the author's experiences among what he is pleased to denominate Indian trout. As regards the remainder of the book, perhaps the most valuable chapter to the practical angler is that dealing with the use of shrimps as a bait, as practised in Ireland, a considerable portion of which originally appeared in the Field. Like most anglers who have tried their hands on fish of many kinds, Mr. Mainwaring unhesitatingly awards the palm, from the point of view of sport, to the lordly salmon, although he confesses to be no adherent to the "dry fly" mode of catching his fish. The general scope of the volume is well indicated by its title, and the author does not even touch upon the natural history side of the subject. R. L.

MATHEMATICAL TEXT-BOOKS.

(1) Elements of Algebra. By G. St. L. Carson and Prof. D. E. Smith. Part i., pp. v+346. (London and Boston: Ginn and Co., 1914.) Price 35.

(2) John Napier and the Invention of Logarithms, 1614. A lecture by Prof. E. W. Hobson. Pp. 48. (Cambridge University Press, 1914.) Price Is. 6d. net.

(3) An Elementary Treatise on the Calculus for Engineering Students. With numerous examples and problems worked out. By J. Graham. Fourth Edition. Pp. xi+355. (London: E. and F. N. Spon, Ltd., 1914.) Price

5s. net.

(4) Constructive Text-book of Practical Mathematics. By H. W. Marsh. Vol. iv.: Technical Trigonometry. Pp. x+232. (New York: J. Wiley and Sons. Inc.; London: Chapman and Hall, Ltd., 1914.) Price 6s. 6d. net.

(5) Arithmetische Selbstständigkeit der europäischen Kultur. Ein Beitrag zur Kulturgeschichte von Prof. N. Bubnow. Aus dem Russischen übersetzt von Prof. J. Lezius. Pp. viii+285. (Berlin: R. Friedländer und Sohn 1914.) Price 10s.

(1)

THE

HE teaching of algebra is still in the experimental stage, and is likely so to remain for many years to come. There are extremists in each camp. There are those who feel that no real progress can be made until considerable manipulative skill has been acquired, and those who hold that the real educational value consists in the absorption of certain general ideas which are largely independent of algebraic drill. The authors of this volume claim to steer a middle course. How far they have succeeded in solving the puzzling problem with which educationists are faced to-day can only be decided by trial. Certainly there are many good features in their book, which is based on the formula rather than the problem. But until an actual trial is made of their methods, it is impossible to pronounce with any certainty on the merits of their scheme, for the ramifications, affecting as they do the whole scheme of education of the nonspecialist, are particularly intricate. We shall look forward with interest to the second volume.

(2) In view of the tercentenary celebration of the publication of John Napier's "Mirifici Logarithmorum Canonis Descriptio," under the auspices of the Royal Society of Edinburgh, the issue of this small volume comes at an opportune moment. Most schoolboys have heard of logarithms and realise their practical utility; but few of them are acquainted with their history, and fewer still with the form in which they originated. Dr. Hobson gives in a simple and very readable manner a comprehensive account of their discovery and evolution; an engraving of Napier and a reproduction in facsimile of a page of the Descriptio add to the attraction of a book that should find its way into every school library.

(3) The opening chapters of this text-book contain in outline such parts of algebra, trigono

(3) This little book, while forming a useful guide to the clinical examination of the blood, contains little that cannot be found in several well-known manuals on this subject. The only novelty, in fact, which we notice in it is the particular technique employed by Prof. Pappenheim. In some respects, indeed, it is lacking. Thus we find no mention of a common method of enumerating the leucocytes by an examination of microscopic fields in the preparation employed for a red-cell count, and there is no connected account of the blood-picture of pernicious anæmia and of the leukæmias. The nomenclature of the bloodcells and their variations is also unusual and difficult to follow by those accustomed to British nomenclature. In some respects the book is interesting reading, e.g. Prof. Pappenheim's views on the derivation of the leucocytic cells. The book contains two beautiful coloured plates of the bloodcells and numerous figures in the text.

25s. net. THE most valuable contribution to this issue of the annual is the report by Messrs. R. M. Dawkins and M. L. W. Laistner on the famous Kamares Cave in Crete. This has been known for more than twenty years as a prehistoric sanctuary, but its complete investigation was carried out only in 1913 under the auspices of the British School at Athens. The early fame of the cave was due to the discovery in the early 'nineties of a number of vases and a few figurines. The work has now been successfully accomplished under considerable difficulties. The general result is that the votive objects which form so striking a feature of other caves and mountain sanctuaries in Crete -the libation tables of Psychro, the shields and bronzes of the Idæan cave, and the figurines of Petsofá are conspicuously absent. The question then arises whether the Kamares Cave was really a sanctuary or only a shelter. The writers conclude that its position renders its use as a shelter improbable; the finds themselves, if they do not positively suggest a sanctuary, equally negative the idea of a dwelling, because houses of the Bronze Age in Crete invariably yield obsidian, while not a single flake was found in this cave. The pottery, again, does not suggest domestic uses. On the other hand, the restricted range of the pottery shapes suggests a sanctuary in which votive vessels were deposited. The cave, in short, was probably a sanctuary of the tutelary divinity of the mountain.

Another side of the subject is illustrated by a report in the same issue of the Journal by Dr. J.

Hazzidakis, of an early Minoan sacred cave at Arkalokhori. Here some interesting vases were unearthed with remarkable bronze swords or daggers. Double axes, undoubtedly symbols of the deity worshipped by the Cretans in the prehistoric period, lead to the conclusion that during the whole of the long period of the Bronze Age, the Minoan periods of Sir A. Evans, the Cretans practised one and the same cult, and this is as much as to say that they were, all through, one and the same people.

The Fauna of British India, including Ceylon and Burma. Edited by Dr. A. E. Shipley, assisted by G. A. K. Marshall. Orthoptera (Acridiida). By W. F. Kirby. Pp. ix +276. (London: Taylor and Francis, 1914.) Price 10s. THE lamented death of Mr. W. F. Kirby left his memoir on the locusts of British India not quite completed. So far as completion was possible it has been effected by the kind offices of Mr. C. O. Waterhouse, who has compiled many of the diagnostic keys. The memoir, which is an admirable piece of systematic work, deals with no fewer than 329 species of Acridiidæ.

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 No notice is this or any other part of NATURE. taken of anonymous communications.]

For

Wet Bulb Temperature and Climatology. It is rather disappointing to find, according to your report of the proceedings of the Section of Physiology of the British Association, the discussion upon climate had to be abandoned because no one was prepared to follow up Prof. Osborne's contribution to it. the points raised by Prof. Osborne, according to what we gather from your short report (p. 322), are of great and vital interest. He emphasises the importance of the readings of the wet-bulb thermometer as indications of what one might call the evaporative quality of the atmosphere as it affects the economy of the human body. Unfortunately the wet-bulb thermometer is untrustworthy for several reasons, and it is well known that physicists treat it with scant respect. Its indications depend in an uncertain way on the physical condition of the air surrounding it, and no one has been able to give a satisfactory method of deducing from its readings the value of the vapour pressure of the atmosphere. Recent experiments of ours with the Kata thermometer prove beyond question that the rate of evaporation from the skin depends directly on the defect of the actual vapour pressure in the surrounding air from the vapour pressure in contact with the skin, and the value of the air vapour pressure can be determined very easily by means of a couple of readings of the dry and wet Kata thermometer.

In order to investigate fully the relation between the climatological condition obtaining in different parts of the United Kingdom and the cooling and evaporative power of the air as measured by the Kata thermometer, we would welcome the help of

volunteers in town and country districts, who would take daily readings with the Kata thermometer, according to directions accompanying each instrument, which we would supply. The time for taking an observation need not be more than five or six minutes. Full details of the Kata thermometer, its construction and use appear in Dr. Hill's Report of Ventilation recently published by the Local Government Board. If any of your readers are interested enough in the matter to take these readings we should be glad if they would communicate with us.

LEONARD HILL.
MARTIN FLACK.
O. W. GRIFFITH.

London Hospital Medical College, London, E.

December 7.

Forests and Floods.

IN the issue of July 16 NATURE published a letter on the above subject in which I showed that pulverised soil holds more of the rainfall than the same soil after it is consolidated by time and rainfall, and it was pointed out that trees by the growth of their roots prevented the consolidation of the soil, and so enabled forest lands to retain more of the rainfall than undisturbed ground.

In that letter it was mentioned water passed more quickly through consolidated soil than through the same soil after it is pulverised. I have recently had an opportunity of observing how this peculiarity of dry soil acts in its disposal of the rainfall. In this district we had a very dry autumn; there was only 043 of an inch of rainfall in the 37 days extending from September 18 to October 24. The soil in the part of the garden to be referred to is of a light and sandy nature, and became very dry, though the plants seemed to get enough moisture for their requirements. The soil at the surface and to a depth of at least one foot seemed to be very dry. Before the end of the drought there were some cold nights, and the surface began to look more moist; this would probably be caused by the condensation of the rising vapour in the cold surface soil. When the rain began on October 25 the surface was thus in a good condition for absorbing it, and as the rainfall was never at any time heavy, and was well distributed over the eight days, during which 1.5 inches fell, none of it would run off the surface, as even during very rapid rainfalls the water easily enters that light soil. A day or two after the rain had ceased I was putting in some bulbs in the border, and was much surprised to find that below a depth of a little more than 3 inches of damp soil all underneath was as dry as it was before the rain began; while I find from tests made with soil lifted from the border, dried and broken up, that 1.5 inches of water wetted it to a depth of 6 inches. It was shown in the previous letter that pulverised soil holds a good deal more water than thoroughly wetted consolidated soil, SO that the border was only moistened by the rainfall to one half the depth it would have been if all the rainfall had been retained by the upper layer of soil. The water evidently had not gone uniformly through the soil, but had made drainage tubes at certain places through which it had passed underground, leaving parts of the soil dry. This we might expect to happen if the soil was not easily wetted, or there were certain parts where the soil was more prepared to take water than at others. Such parts we might suppose to be those up which the water vapour rose most freely, and would therefore be damper, or the water may have escaped down the outsides of the roots of the plants.

Now in well stirred soil there are none of these preferential routes for the escape of the water.

In illustration of these preferential routes one might point to the condition of the soil on vertical cuttings which one sometimes sees where roads are cut through banks, or on any deep cutting made in soil. It will be noticed that these cuttings have no vegetation on them, and that the soil gradually weathers away, leaving an overhanging turf. It will be noticed that the soil on the face of the bank under the turf remains dry, all the summer at least, however heavy the rainfall. The water evidently does not percolate straight to the soil underneath, but takes a preferential route, backwards from the turf, and downwards behind the dry soil. The dry soil seems to reject the water, which prefers to pass through the damp soil behind it. It was noticed at the end of November this year that these banks were still dry though 6-4 inches of rain had fallen since October 25.

Some soils seem to have very little affinity for water, and act very much in the same manner as most substances do towards mercury. For instance, when one watches the seashore on a calm sunny day while the tide is rising one often sees all kinds of dry particles which are much heavier than water floating on the surface; these particles may be sand or other earthy matter. Again, when walking over bare sandy soil one sometimes sees a curious illustration of this objection of dry sand to being wetted. If the weather has previously been very drying and there comes a shower of rain, some of the little hollows in the sand will get full of water, and retaining it as well as if they were made of puddle clay. Of course these cups are very shallow, otherwise the hydrostatic pressure would be sufficient to break the water film between the grains of sand.

However, repulsion of the water by ordinary soils does not seem to explain the passage of the rainfall through the soil without wetting it equally. A small clod of soil from the border referred to was dried, after which it was placed in a shallow vessel in which was less than 1 mm. of water. The clod quickly absorbed the water, raising it to its top surface, which was fully 1 cm. above the level of the water.

It is difficult to explain this preference of the water for certain parts of the soil, where the soil wets so easily on contact with it. Is it possible that the water by sinking a little deeper at certain places comes to exert a kind of negative hydrostatic pressure, and so draw the water from the surrounding area? This, if once started, would have a gradually increasing influence owing to the increasing "head."

The border referred to was opened up at a number of places on November 23, after nearly 4 inches of rain had fallen, and even then there were parts of the soil quite dry a few inches below the surface. It is evident that something is still required to explain these preferential routes of the water in dry consolidated soil. There are none of them in pulverised soil, and this points to the probable advantage in "dry farming" of stirring the soil to a sufficient depth to retain the whole of the rainfall, in addition to the usual practice of stirring the surface soil after rainfall to form a mulch to check its loss by evaporation. JOHN AITKEN.

Ardenlea, Falkirk, December 5.

On an Apparently Distinctive Character of the Genus Bufo.

ON p. 38 of Mr. G. A. Boulenger's valuable work on the "Tailless Batrachia of Europe" it is stated of the vertebral column of the Anura that "In those forms in which the vertebræ are procœlous the eighth