MR. EDWARD ARNOLD'S NEW BOOKS. THE EVOLUTION THEORY. Professor of Zoology in the University of Freiburg. Professor J. ARTHUR THOMSON and MARGARET THOMSON. SPECTATOR.-"These two massive volumes are in themselves a monument of research and speculation that will out-live much of the perennial brass of the nineteenth century." Verlag von WILHELM ENGELMANN in LEIPZIG. VOR KURZEM ERSCHIEN: NEWCOMB-ENGELMANNS POPULÄRE ASTRONOMIE. DRITTE AUFLAGE. Herausgegeben von Dr. H. C. VOGEL, Direktor des Astrophysikalischen Observatoriums zu Potsdam. MIT 198 ABBILDUNGEN IM TEXT UND AUF 12 TAFELN. GR. 8". 1905. GEHEFTET M 15.-; IN LEINEN GEB. M 16.-. STANDARD FORKS. The illustration shows one of our Standard Forks, mounted so that its vibration can be electrically maintained. The position of the electro-magnet can be adjusted lengthwise of the fork, as well as laterally and vertically. The height of the mercury in the contact cup can also be finely adjusted. Complete with 1 Standard Fork, £8. (The forks are supplied making 50, 100 and 200 vibrations per second, as desired.) Stand without Fork, £4. THE CAMBRIDGE SCIENTIFIC INSTRUMENT COMPANY, LTD., THURSDAY, AUGUST 24, 1905. SCHOOL MATHEMATICS. Easy Graphs. By H. S. Hall, M.A. Pp. vii+64. (London: Macmillan and Co., Ltd., 1905.) Price IS. under review it can be studied and developed with the completeness which its importance demands, arithmetically, algebraically, and geometrically. Students are taught the use of logarithms, and also sufficient trigonometry to enable them to solve rightangled triangles; they use compasses and setsquares, draw simple plans and elevations, and make dimensioned free-hand sketches in pictorial or other proPp.jection, and they are introduced to the notion of a The Rudiments of Practical Mathematics. By A. 2s. 6d. Elementary Practical Mathematics. By H. A. Stern, A First Algebra. By W. M. Baker, M.A., and A. A. Algebraical Grounding. By D. E. Shorto, M.A. Pp. 46. (London: Rivington, 1905.) Price 18. net. Examples in Algebra. By Charles M. Clay. Pp. vii+372. (New York: The Macmillan Co.; London: Macmillan and Co., Ltd., 1905.) Price 48. net. Geometrical Conics. By G. W. Caunt, M.A., and vector by means of displacement and velocity dia- The The "First Algebra," by Messrs. Baker and Bourne, is adapted from the first part of the authors' larger work, and, proceeding in the customary order, carries the subject up to quadratic equations and fractional and negative indices. Arithmetical and graphical illustrations are freely introduced, and a special feature of the work is its very easy graduation and the large number of examples, some oral, provided at every stage, so that students using the book properly cannot fail to obtain a full knowledge of the subject. The answers are completely given, and themselves extend to thirty-five pages. The book gives an admirable first course in algebra. The "Rudiments of Practical Mathematics," by Messrs. Consterdine and Barnes, is a very excellent treatise, intended more particularly for students above twelve years of age who are preparing for industrial pursuits. The heuristic method is in the main followed, and the material for exercises is largely drawn from the students' own measurements, suitable objects of a simple kind being provided for this purpose, with appliances for measuring lengths, areas, volumes, weights, and times. Thus every rule and process is definitely associated with some direct quan-gressions, and the binomial theorem. titative application, and the subject assumes a real and living interest and cannot fail to be assimilated. The subject-matter is purposely confined to that which is in daily use in industrial occupations, so that there is time for this to be dealt with in a very thorough manner. In this volume arithmetic, algebra, and geometry are so interwoven that any attempt at separation would appear quite unnatural. Thus when an important principle, say that of proportion, is Mr. Shorto's Algebraical Grounding" is a collection of the definitions, axioms, laws, rules, and proofs belonging to the subject, without examples, and arranged in logical sequence. It is intended as a summary of the oral teaching usually imparted, and could well be used in conjunction with a collection of examples. It includes logarithms, the pro The collection of eight thousand "Examples in Algebra," by Mr. Clay, has been accumulating for the last twenty years, during which time the author has been engaged in teaching the subject in America, and has found that the examples provided in the ordinary text-books are deficient in both quantity and variety, and not regularly graded. The teacher will here find examples in superabundance, increasing in difficulty by almost insensible steps from the simpler and also the time required for the completion of the exercises in the use of symbols to the difficult problems in surds, theory of exponents, quadratics, and in arith-❘ canal. Eventually, after the failure of the first metical and geometrical progressions. The work shows no trace of having been influenced by the reform movement going on in this country, but teachers will receive valuable hints and much useful matter by consulting this thorough and extensive compilation. The Geometrical Conics" by Messrs. Caunt and Jessop is a preliminary deductive course for students about to enter on a systematic study of analytical geometry. Only the leading properties of conics are dealt with, and these are established when possible from corresponding properties of the circle by the aid of the modern methods of projection. The book is well suited to its purpose. PANAMA CANAL. Problems of the Panama Canal. By Brig.-General THE company, a New Panama Company was formed in 1894 (given by a misprint as 1904 in the introduction); and the works for a canal with locks were slowly proceeded with as funds permitted, until at length, last year, the United States Government purchased the undertaking with the view of carrying it out as a national work. Early this year an engineering committee of the Panama Commission recommended a sea-level canal again, with a bottom-width of 150 feet and a minimum depth of 35 feet, and the necessary duplicate tidal locks near the Panama end, capable of accommodating vessels up to 1000 feet in length and 100 feet in width. The principal objections to the formation of a canal across the isthmus at sea-level throughout, are the time, difficulties, and cost involved in making a cutting, reaching a depth of 317 feet, in unfavourable strata exposed to tropical rains, and the efficient control of the River Chagres, which crosses the line of the canal on the Atlantic slope in several places, and the floods of which will become a more serious peril to the maintenance of the canal in proportion as the water-level of the canal is lowered. The objection of siderably less importance in a national than in a private undertaking; but the floods of the Chagres appear liable to prove a standing menace to the safety of a tide-level canal. The Isthmian Canal Commis sion of 1899-1901 expressed its disapproval of a sealevel project in the following words : HE author of this book acquired distinction in hydraulics in early life by the publication, in conjunction with Captain Humphreys, of their well-cost, and, to some extent, that of time, are of conknown “" Report on the Physics and Hydraulics of the Mississippi River" in 1861; and, accordingly, this statement of the problems of the Panama Canal, in which hydraulics are so largely involved, by such a high authority, who, as a member of the technical committee of the New Panama Company, devoted seven years to their study, deserves the most careful consideration of the American nation, for whose guidance this volume has been published. It appears at a very opportune time, when the United States Government has undertaken the completion of the works, but has entrusted to a commission of engineers the consideration of the precise designs for the canal. The chapters on the "New Panama Company,' with which the author was connected, "The Rival Routes" of Panama and Nicaragua, the "Physical | "The cost of such a canal, including a dam at Alha juela, and a tide lock at Miraflores near the Pacific end, is estimated at not less than 240,000,000 dollars. Its construction would probably take at least twenty years. This Commission concurs with the various French Commissions which have preceded it, since the failure of the Old Company, in rejecting the sealevel plan. While such a plan would be physically practicable, and might be adopted if no other solution were available, the difficulties of all kinds, and especi ally those of time and cost, would be so great that a canal with a summit level reached by locks is to be preferred." The author regards these remaining difficulties as very important; and, after discussing them, and particularly the problems concerning the control of the Chagres, he concludes his book with the following expression of his opinions :- "It is the unanimous opinion of all the engineers who have had practical experience in canal work, and time to thoroughly study the problem, that no sealevel projet without locks, and no sea-level canal even with a tidal lock, is practicable that would be comparable in ease and safety of transit to one equipped with modern locks, and planned to take advantage of all the desirable elements which the natural conditions offer. Why, then, waste an extra ten or a dozen years, and untold millions of dollars, to execute a scheme which the investigations of thirtyfive years have demonstrated to possess only a sentimental merit due to the imagination of M. de Lesseps ; Congress and the American people are impatient for the opening of the best possible canal." OUR BOOK SHELF. The American Thoroughbred. By C. E. Trevathan. (American Sportsman's Library.) Pp. ix + 495; illustrated. (New York: The Macmillan Company; London: Macmillan and Co., Ltd., 1905.) Price 8s. 6d. net. FROM the point of view of the naturalist, the interest of this volume (which is no doubt an admirable guide to everything connected with racing on the other side of the Atlantic) is concentrated on the author's remarks with regard to the origin and development of the American thoroughbred. As a matter of fact, the racehorse in America has been produced mainly from an English ancestry, and is thus essentially of the English type; and the one matter for regret in his treatment of the subject is that the author does not appear to point out any features by which the American breed may be distinguished from its European prototype, as it is difficult to believe that minor differences between the two do not exist. The first thoroughbred imported into America seems to have been Bulle Rock, a horse foaled in England in 1718 and landed in Virginia in 1730. He was a scion of the Darley Arabian, and had also the blood of the Byerly Turk on the maternal side. The product of native-bred mares (that is to say, mainly the descendants of horses imported by the Spanish conquerors, which were themselves largely of Barb blood) by Bulle Rock formed the first foundation of the modern American racing stock. Diomed was another famous English stallion imported into Virginia in the old days; but long after the definite establishment of an American thoroughbred stock, considerable improvement was effected therein by the importation in 1836 of Glencoe, at that time a renowned English horse. Glencoe was by Sultan, and while in England sired Pocahontas, the dam of Stockwell, Rataplan, and King Tom, the three greatest sires the English turf has ever seen, and to one of which almost every living English racehorse can trace descent. With such a sire the future of the American thoroughbred was assured. In conclusion, we may congratulate the author on having added a valuable volume to a valuable library, as well as on having made an important contribution to our knowledge of the ancestry of the American racehorse. R. L. speculations concerning some of the extinct forms, and there are more misprints than ought to be. The book also lacks adequate illustrations. It is, however, a worthy sequel to Mr. Pycraft's earlier "stories" of birds and fishes, and we hope he may soon complete the series by a final volume on the mammals. Digest of the Evidence given before the Royal Commission on Coal Supplies (1901-1905). Vol. i. Pp. xiv +474. (London: The Colliery Guardian Co., Ltd.) Price 218. THE Colliery Guardian has done useful work in preparing this digest of the evidence given before the Royal Commission on Coal Supplies. The 25,662 questions and answers contained in the official minutes of evidence do not constitute an attractive form of technical literature; but with the matter rearranged and classified under separate heads, and the interrogative converted into the narrative form, it is surprising to find what an enormous amount of valuable information has been got together. With the exception of a brief historical introduction, no comment is made on the evidence, and such additions as the witnesses have found desirable when revising their evidence have been printed as footnotes. The work will be completed in three volumes, the subjects dealt with in the first being the working of thin seams, the limit of depth in mining, waste in working and coal-cutting machinery. There is a good index and a useful bibliography of the subjects discussed. Printed in large type, with the illustrations admirably reproduced, the work forms a valuable companion to the official Blue-books, and, indeed, from the point of view of the mining student, may replace them altogether. Wasps, Social and Solitary. By George W. Peckham and Elizabeth G. Peckham. With an introduction by John Burroughs. Pp. XV+311; illustrated. (London: Constable and Co., Ltd., 1905.) Price 6s. net. THIS book is founded on a series of papers published some years ago by the Wisconsin Biological Survey under the title of "Instincts and Habits of the Solitary Wasps," with much new matter added. It is a record of very patient field observations on the lines with which Fabre's well-known "Souvenirs Ento The Story of Reptile Life. By W. P. Pycraft.mologiques" (constantly referred to, and compared by This is a valuable addition to the "Newnes' Library of Useful Stories. Mr. Pycraft not only writes in a readable and entertaining style, but also has the happy faculty of selecting precisely those facts which enable him to expound general principles. The "Story of Reptile Life" is not an elementary book of natural history in the ordinary sense, but the outline of a really scientific treatise which is not too technical to be understood by a beginner. After some introductory remarks explaining that he has to deal with a race "whose glory has departed," the author proceeds to describe each of the groups of surviving reptiles, with some reference to their immediate ancestors as revealed by fossils. In each chapter he treats first of the most salient points in anatomy, and then proceeds to select a few of the more important living species for detailed notice. The account of the existing reptiles is followed by two chapters on domestic life and reptilian liveries. The book then concludes with chapters on the extinct flying reptiles, land reptiles, and sea reptiles. We have detected no serious errors, though it is difficult to accept all the author's our present authors with their own) have made us familiar. The wasps discussed are chiefly those which provision their nests with caterpillars and other insects, or with spiders; and the genera noticed are Vespa, Ammophila, Sphex, Rhopalum, Odynerus, Aporus, Crabro, Bembex, Cerceris, Philanthus, Trypoxylon, Pompilus, Tachytes, Chlorion, Pelopous, Astata, Oxybelus, &c., all of which (Sphex, Bembex, and Chlorion excepted) include British species. Many persons are interested in the habits of insects who have not time or opportunity to observe them for themselves, and to all such we heartily commend this important work on the manners and customs of North American wasps. W. F. K. X-Rays: their Employment in Cancer and other Diseases. By Richard J. Cowen. Pp. viii+126. (London: Henry J. Glaisher, 1904.) Price 2s. 6d. net. THE author of this work states in his preface that he has made no effort to summarise all the valuable work which has been done in radiotherapy, and he has only tried to select such part as seems to him to be most likely to assist those practitioners in the therapeutic properties of X-rays, the choice of apparatus, and the technique. In the first twenty-four pages the apparatus is considered, and the remainder of the work, with the exception of two short chapters, is devoted to brief consideration of a number of skin affections, including malignant disease. The book will certainly be of service to those for whom it is intended, and many practitioners who desire to become acquainted with this new branch of electrotherapeutics will find it a useful introduction. The work is well written and unpretentious, and Dr. Cowen has succeeded in the aim laid down in his preface. Neue Abhandlungen über den menschlichen Verstand. By G. W. v. Leibniz. Translated, with introduction, by C. Schaarschmidt. Second edition. Pp. lxviii+ 590. (Leipzig: Dürr'sche Buchhandlung, 1904.) Price 6 marks. Immanuel Kant's Logik. By G. B. Jäsche. Third edition. New edition by Dr. W. Kinkel. Pp. xxviii+171. (Leipzig: Dürr'sche Buchhandlung, 1904.) Price 2 marks. Lazarus der Begründer der Völkerpsychologie. By Dr. Alfred Leicht. Pp. 111. (Leipzig: Dürr'sche Buchhandlung, 1904.) Price 1.40 marks. THE first two of the above-mentioned works appear as parts of the excellent "Philosophische Bibliothek.' The translation of the Leibniz into the philosopher's native tongue appears to be all that could be desired, and the introduction gives an analysis of the work. We gather that some 460 explanatory notes are to be found in the succeeding volume of the series. This edition of "Kant's Logik" is intended to supersede the uncritical one of Von Kirchmann, who relied only on the second Hartenstein edition of 1868. The present editor has gone back to the original text of Jäsche, and has also compared the other important editions, the first Hartenstein and the Rosenkranz, both of 1838. The spelling is completely modernised. Prof. Moritz Lazarus was, with Steinthal, the founder of the Zeitschrift für Völkerpsychologie und Sprachwissenschaft in 1859, and his works not only contain much sound psychology, but are also permeated by a fine ethical spirit. His long life and labours are here described by a singularly appreciative disciple. 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.] British Fruit Growing. THE question of "the diversity of yield from farms in the same neighbourhood to which you referred in your article on the report of the fruit committee is, as Mr. Alfred Walker remarks, one of very great complexity. No evidence on this subject, however, was offered to the fruit committee by the numerous growers who appeared as witnesses before them, and it would certainly seem to be a subject more suited for investigation at an experimental station than one which could be dealt with by a departmental committee. Meteorological conditions are, no doubt, primarily responsible for most failures of cropping, and, in a climate such as that of our islands, we can never hope to do more than mitigate the evil effects of inopportune cold. The destruction of the blossoms is generally due-as in 1903to cooling by radiation, and the best safeguard against this form of cooling is a fairly elevated position, and a lie of the ground favourable to the draining away of the cold air from the plantation. Good air drainage is probably more important in fruit growing than good water drainage. Various means have been investigated for re ducing radiation by artificial means, but the results have not yet proved themselves to be successful, at any rate from an economic point of view. The destruction of blossoms, however, is caused sometimes by a low atmospheric temperature produced by means other than surface radiation. This was the case in the present year, when the destructive cooling agent was a cold wind. A warm, low situation, with plenty of shelter, will afford some safeguard against damage from such a source; and these, unfortunately, are just the conditions which will increase the danger from radiation frosts. There is no doubt, however, that the damage done by a low temperature is not always done in a direct manner. A continued spell of cold weather at the blossoming season is inimical to the activity of the various insects on which pollination mainly depends, and we are not yet in a position to say that a sluggish action of the roots and leaves may not itself be directly detrimental to the process of fertilisation. The number of apples and, still more, of pears which have been imperfectly fertilised, and have, therefore, dropped prematurely, have been very noticeable this year. What part the nature of the soil plays in modifying the action of cold on the trees is one which is very difficult to foretell or to determine. We can never have two plantations in different soils while being in exactly similar positions; and the question whether a blossom will be reduced to a lower temperature by radiation in the moist air overlying a clay soil than it would be in the dryer air overlying a gravel soil, or whether, if reduced to the same temperature in both cases, it would suffer more in the one than in the other, is a question on which we cannot dogmatise. We must not be misled by the feeling of cold experienced in two such cases by the human subject; indeed, watering the trees and ground is one of the methods suggested for obviating the effects of radiation frosts. Differences of soil, also, will act indirectly in the matter by affecting the root-action and the forwardness of the blossoms. по On one point, however, I think there can be doubt, namely, that the best safeguard against injury by frost, where frost is inevitable, is a healthy condition of the tree itself. It has been a matter of continued observation that with similarly situated plantations, and with similar trees in the same plantation, those which are most healthy will nearly always suffer least from frost. It is specially noticeable that with trees which are weakly, even when they carry (as will often happen) a great abundance of blossom, injury from frost is very severe, although the abundance of blossom should be favourable to some of these being preserved from destruction. It is in this direction-the general health of the trees and the raising of healthier and hardier varieties-that success in diminishing loss by frosts will most probably be achieved. It is hardly probable, I think, that much will be effected, at any rate in the case of apples, by raising varieties blossoming late enough to escape frets. These frosts, as we all know, often occur very late in the year, and though every day by which the blossoming is retarded must, on the average, diminish the risk of its destruction, there would appear to be but little chance of our being able to retard it sufficiently to diminish that risk to any material extent. It must be remembered, also, that though we might raise a late blossoming apple, it is a hundred chances to one that the fruit would be able to compete in the market with known varieties. The flowers of the large majority of English apples would appear to open within a period of about ten days. Observations made this year on 117 varieties gave a total range of 16 days, but 98 per cent. of these varieties opened within a range of 13 days, and 84 per cent, within a range of 9 days. The extent of the variation, therefore. is not sufficiently large to offer much promise of success in raising a variety which would escape frost by its lateness of flowering. It is noticeable, however, that our English apples appear to be rather earlier in their flowering than varieties belonging to other countries, when all are grown under the same conditions. The results obtained at Woburn this year were as follows, the dates being those of the opening of the first flowers, and the fractions of dates arising, of course, through the taking of the means. The number of varieties under observation are given, and |