LES ORAGES. Application des ondes hertziennes leur observation. Julien Loisel, docteur-s-sciences, mtorologiste l'observatoire de Juvisy. Prface par Camille Flammarion. Paris: G. Thomas, 1912, 8vo.; pp. vii, 120. This is destined to be regarded as a standard work on thunderstorms; and as no such work exists in English, it is commended to the attention of American students and readers. The book is not difficult reading, as it involves but little mathematics, but on the other hand it is a serious treatise, not written to divert the multitude. Thunderstorms are just now occupying the European mind to an unprecedented extent, mainly for two reasons: (1) Great efforts are being made in the Old World to avert or mitigate the destructive effects ot hail, whether by hail-shooting,' hail-rods, hail insurance, or protective measures contingent on timely warnings, and hail is the accompaniment of thunderstorms. In France alone hailstorms cost the country anywhere from $8,000,000 to $27,000,000 a year in ruined crops. (2) Thunderstorms constitute a grave danger to the aeronaut. Dr, Loisels book is a handy digest of the recent literature of his subject, fortified throughout with references to original sources of information, including many memoirs published in the scientific journals during 1911 and 1912. Thus we find the very latest attempts to explain the electrical field of the atmosphere, which take into account big and little ions, ultra-violet light, radioactive discharges from the sun and the earth, and the other novel agencies belonging to twentieth century electrical science. In the chapter on the electrification of clouds, the author presents not only the Wilson-Gerdien and Simpson hypotheses, but some objections to the latter put forth by J. Key in a university thesis published in 1912, which has hardly yet found its way into the scientific libraries. The description of lightning phenomena might well have given more emphasis to the epoch-making researches of Walter, and might have been a little more positive as to the cause of black lightning, but is, on the whole, adequate. Here, as elsewhere in the book, we find a well-chosen collection of excellent photographs, lacking only the moving-camera pictures which Dr. Walter and others have made so familiar to the readers of the scientific journals, and which should certainly be included in any modern work on thunderstorms. The relation of thunderstorms to the general barometric conditions is brought out in a chapter of text and charts. The author avoids giving too much prominence to the line-squall type of thunderstorm, with which M. Durand-Greville's name is inseparably connected, and quotes the opinion of Angot that this type of storm is not so general as has been assumed in recent meteorological literature. A chapter is devoted to the question of predicting the movements of thunder storms from> the ordinary weather map, and from the reports of a dense network of observing stations especially installed for this purpose; and points out how successfully such predictions have been made in Germany for the benefit of aeronauts. This subject leads up to a long final chapter on ceraunographs, or thunderstorm recorders. THE ROMANCE OF SUBMARINE ENGINEERING. Containing Interesting Descriptions in Non-technical Language of the Construction of Submarine Boats, the Salving of Great Ships, the Recovery of Sunken Treasures, the Building of Breakwaters, Docks, and Many Other Feats of Engineering Beneath the Surface of the Water. By T. W. Corbin. With 54 illustrations and diagrams. London: Seeley, Service & Co., Ltd., 1913. The only serious omission that we can call attention to in this book is the failure to discuss the use of compressed air in the raising of sunken ships, a method that was used with conspicuous success in raising the Barbarian and other vessels. The book on the whole may be commended for presenting a very readable account of diving apparatus, submarine boats, caisson work, and submarine apparatus in general. SAW FILING AND MANAGEMENT OF SAWS. By Robert Grimshaw. New York: Norman W. Henley Publishing Company, 1912. 16mo. Price, $1. This is a book which is designed as a practical aid to those who use saws lor any purpose. While, as its title implies, it treats principally of saw-filing, it also goes into the questions of gumming spring-setting, and swaging. WIRELESS TELEGRAPHY AND TELEPHONY SIMPLY EXPLAINED. A Practical Treatise by Alfred P. .Morgan. New York: The Norman W. Henley Publishing Company, 1913. Price, $1. This book embraces a complete and detailed explanation of the theory and practice of modern radio apparatus and its present-day applications, and contains a chapter on the possibilities of its future development For those who wish an accurate, simply-worded book, suitable for a novice, Mr. Morgan'3 volume can be heartily recommended. THE CINEMATOGRAPH AND NATURAL SCIENCE. By Leonard Donaldson. London: Danes, Ltd., 1912. 12mo. Price, 2s. 6d. net. In this excellent handbook Mr Donaldson has most interestingly revealed the part that the motion picture has played in science during the J last few years. He has described for the benefit ?? tha public, whose knowledge of motion photography is more or less limited to the amusement phase, an exposition ol the scientific achievements ol the cinematograph, coupled with various suggestions as to its possibilities ol further utility in scientific research. He therefore discusses the motion picture as an educator, and shows how successfully motion pictures have been used in \ schools. That the motion picture is an aid to operative surgery is revealed in a chapter which includes, among other things, the views of Dr. Doyen, which have been rather widely quoted in medical periodicals. 80, too, the author takes up the subject of the X-ray and the cinematograph. He shows the value of the moving picture in biological experiments and in photographing the pulsations of the heart, as well as in recording the flight of insects. A whole chapter is devoted to micro-cinematography and bacteriology. Interesting is his account of the manner in which natural phenomena are recorded on the moving film. How the motion picture has been used in astronomy, exploration, physiological botany, wireless telephony, aerial navigation, etc., is also taken up. LE TEMPS QTJ'IL FAIT; LE TEMPS QU'IL FEKA. Notions de meteorologie a l'usage des aeronautes et des aviateurs. A. Berget. Paris: Librairie Ch. Dela-grave, 1912. 8vo.; 261 pp.; illustrated. For some years to come every new publication on the new science of aeronautical meteorology will inevitably be compared with the pioneer work in this field, Linke's Aeronautische Meteorologie (Frankfurt, 1911). Few books will not suffer by the comparison, and Dr. Berget's is not one of the few. Only the fact that the literature of this important subject is still meager, and that many aeronauts who are able to read French are, to their infinite disadvantage, unable to read German, makes it desirable to call attention in these columns to the first attempt on the part of a Frenchman to cover the subject in some detail. The limits of aeronautical meteorology are not sharply defined, but Linke set a commendable example in confining his work very closely to matters of practical importance to the aeronaut, and not duplicating more than was necessary of the information found in ordinary works on meteorology. If Berget had followed the same plan his book would have been about one tenth its actual size. The aeronautical information is diluted to the last degree, though occasionally it is valuable, and even includes a few facts that Linke overlooked. Berget's meteorology is not always sound. The most remarkable blunder in his book is found on page 54, where it is stated that the isothermal layer is only three or four kilometers thick, and that the fall of temperature with increase of altitude (the vertical temperature gradient) is resumed above it. This statement bears eloquent testimony to the author's unfamiliarity with almost everything that has been written about upper-air meteorology (a whole library in itself) during the past eight years. The author also has faith in the efficacy of reforestation and inland seas to increase the rainfall, and in cannonading to avert hailstorms, doctrines that only the dilettante proclaims without, at least, a pace to the authorities. Why is hail-shooting mentioned at all in a work on aeronautical meteorology? Because, of course, aeronauts must be warned to keep out of range when this kind of bombardment is in progress! True, the hail-cannon discharges no projectile; but think of the eddies"! The present reviewer diffidently suggests a comparison between the violence of these artificially-produced eddies at an altitude of 400 to 500 meters and that of the natural atmospheric billows and whirlpools which are negotiated with ease by every airman. For readers already well grounded in meteorology there are some useful and suggestive things in Berget's book. On pages 19 to 26 there is a clear exposition of the relations between actual and relative velocity in the air, and of the limits imposed by the winds upon the actual dirigibility of dirigibles. Elsewhere there is enough grain scattered through the chaff to render the book well worth reading. However, the amount of pertinent information omitted considerably exceeds what is included Not to multiply examples, although whole chapters are devoted to various methods of weather forecasting, not a word is said about the special storm warning services for aeronauts which have grown up in Germany in the last few years, and are beginning to be imitated in other countries. As the book is French it contains no index, of course. But, strange to say, neither does Linke's, which is German! AN EXTENSION OP THE DEWET DECIMAL SYSTEM OP CLASSIFICATION APPLIED TO THE ENGINEERING INDUSTRIES. By L. P. Breekenridge and G. A. Goodenough. Originally issued as Bulletin No. 9 of the Engineering Experiment Station in 1906. The filing and classification of engineering data has become a matter of much importance, and this bulletin was prepared for use as a guide in carrying out such work. The original edition of Bulletin No. 9 was subject to the usual gratuitous distribution, and the subsequent demands were such that a second edition was printed and ultimately distributed. Altogether 20,000 copies were sent out. The demand having continued, it was finally decided again to revise and to print a limited edition. This has now been accomplished and the revised bulletin, much extended as compared with the original edition, is ready for distribution. It presents subdivisions of subjects in such detail as to constitute a complete classification for most engineering industries, even though they are highly specialized. The revision has been made in accordance with the 1911 edition ol Decimal Classification by Melvil Dewey.