Journalof Atmospheric and Terrestrial Phgsinr,1909,Vol. 31,p, 889. Pergemon Preae.Printedin NorthernIreland
BOOK REVIEWS Von Dr. rer. nat. Hans Volland. 232 S&en, 66 Bilder. Efalin DM 36, (Best. -Nr. 7505)
Die Ausbreitung langer Wellen.
THIS little book gives an account in German of the theory of the propagation of waves of frequency 10~~than 300 kHz with particular reference to those of frequency less than 30 kHz and as low as 1 Hz. At the low frequency end of the spectrum naturally occurring v.1.f. and u.1.f. radiations are discussed. Propagation within the earth-ionosphere wave-guide is considered and allowance is made for its curved nature. Reflection and conversion coefficients are calculated for some model ionospheres and for a range of frequencies and angles of incidence, but the results are not compared with experimental observations. Indeed, experimental results and interpretation of measurements are discussed only when they illustrate the theory. J. A. RATCLIFFE
The Radiation Belt and Magnetosphere.
WILMOT N. HESS.
Blaisdell Publishing Company,
1968, 548pp, $16.50. TEE DISCOVERY of particles trapped in the “Van Allen” belts wa8 made in 1958: since then they have been extensively studied experimentally and theoretically so that now there are more than 2,500 papers about them. When an important new discovery is made, and followed up as rapidly as this one, it is unusually difficult for workers in allied subjects to follow what has been done. An authoritative and readable guide is required. This book provides, in ideal form, just what is wanted. Experimental details, of the kind that frequently make papers on the subject difficult to read, are excluded: the theory is dealt with simply, and with full explanation in physical terms. The approach is logical and direct; although a full understanding of physical principles is assumed it is not supposed that the reader has previously studied this particular subject in any detail. After a particularly lucid introduction the book deals in succession with how particles move in magnetic fields, where they might come from and go to, those trapped in the inner zone either naturally or as the result of atomic explosion, those in the outer zone, and the behaviour of the outer edge of the magnetosphere. Chapters on the aurora, synchrotron radiation, and low energy particles follow. The chapter dealing with the confusing topic of the magnetospheric boundary is particularly helpful, especially because it contains a full account of what is known about the geomagnetic tail. For many readers of this Journal the flnal chapter on low energy electrons will have especial interest, since it concerns those parts of the magnetosphere adjacent to the ionosphere. It discusses magnetic storms, optical emissions, VLF radiation, and electric fields. An appendix describes, in some detail, the proton and electron environments in which satellites in the inner zone, the outer zone, and in synchronous orbits will find themselves. Another appendix l&3 all the experiments that have been made in space vehicles to measure energetic particles near the Earth, the Moon, Mars and Venus. The book has been planned and written with the reader always in mind, it is a delight to read: Dr Hess must be an eminently successful teacher. J. A. RATCLIFFE 889