C & I continued Superconducting magnet for Air Force
dynamic generators for airborne applications. These generators can produce 1-2 MW for periods of 1-20 rain. By using a superconducting magnet, the weight of the generator system will be reduced from several hundred tons to a few thousand pounds. The illustration shows a superconducting solenoid being prepared for testing.
Ferranti-Packard Ltd of Toronto, Ontario, Canada, has won a $250 000 order to develop and construct a large transverse field superconducting magnet for a Defence Research Sharing project, jointly sponsored by the Canadian Defence Research Board and the USAF Aeropropulsion Laboratory at the Wright Patterson Air Force Base. The magnet to be supplied, a dipole magnet measuring 36 in. with a 12 in. bore, will produce a field of 75 000 Oe at - 2 6 9 C. An unusual feature is that this field is generated transverse to the bore of the magnet rather than parallel, as in the case of solenoid magnets. Solenoid magnets are normally easier to produce than dipole magnets, since the winding of the conductors in to coils is much less complex. However, the FerrantiPackard Superconductivity Research Group have developed new techniques for winding in dipole magnets and these will be used in the magnet. The magnet will be used to develop magneto-hydro-
BOOKREVIEWS Superconductivity E. A. Lynton THIS handy little book in its new edition remains as appealing as ever. With its combination of compactness and cheapness, coupled with broadness of survey, it has no equal. Its primary function continues to be that of introducing the subject of superconductivity to physicists who are of about first degree standard, but the inclusion of as many as 500 references adds to it the role of an elementary source book. Naturally, a certain shallowness of coverage is apparent in a book which is only 200 pages in length, but the treatment is well balanced and does nevertheless possess the cardinal virtues of easy readability and reasonable accuracy. Doubtless those readers who are familiar with the 1964 edition will not be surprised to learn that rather fuller accounts of the Ginzburg-Landau theory and type II superconductivity are now provided. Some other obvious additions include a couple of pages on the Josephson effect and macroscopic interference effects. But besides this, the entire monograph has been revised wherever it was required in the text. The only exception is Table I which contains some minor errors and several graver omissions. This table claims to list 'all presently known superconducting elements and their characteristic /4o and T,.'. Yet it omits Be, Mo, 7-U, and the admittedly dubious HI', and overlooks the high pressure metallic forms of Bi, Ge, P, Sb, Se, Si, Te, and Ce). Published by Methuen, London, England; 3rd edn. CRYOGENICS
In conclusion, I heartily recommend this introduction to the complexities and marvels of superconductivity to all newcomers to the field, but it is doubtful whether many, if any, owners of the 1964 edition will wish to replace it with this latest one. G. T. MEADEN
Theorie der elektromagnetischen Wellen nach Vortr gen im Nachrichtentechnischen Kolloquium der Universit t Bern G. Epprecht, H. Carnal, E. Schanda, H. Severin, H. Bremmer, and D. J. R. Stock THIS is a very remarkable little book, because it combines in one slim volume, an introduction to vector analysis and electromagnetic theory, with an authoritative and informative treatment of a number of subjects of great current interest. These include surface waves, propagation in anisotropic media, for example, plasmas, amplification in periodic structures, wave propagation in the ionosphere and exosphere, and topics on aerials. The mathematical treatment is as simple as possible and emphasizes intuitive insight. H. MOTZ Published by Birkh&user Verlag, Basle, Switzerland (1969); 128 pages. 223