KEVlEWS 369

Locust Survey. The fruit of the co-operation is a rainfall map on which the isoliyets have been drawn not only to fit the mean annual totals at the comparatively sparse network of raingauges but also to take account of the detailed topography and vegetation. The use of ecological information in constructing a rainfall map represents, in the words of the authors, a major innovation in technique. It is unfortunate then, that no more than a few lines are given to this aspect of the work. The rabbit is impressive but we are not shown the inside of the hat. The authors have faced a number of difficult problems, including those of reconciling mean annual values calculated for periods varying from one to sixty years, and of incorporating information on mixed forms of vegetation, the types of which most respond in different measures to the rainfall of the past season, the past five years, or the past thirty years. Discussion of the solution or circumvention of these problems would have been welcome.

The variation from year to year in annual totals for a given station is high in the region considered. This is illustrated by statistics for individual stations and by a diagram which shows, for a given mean rainfall, the range within which the annual totals will probably lie in 2 out of 3 , 19 out of LO, and 99 out of 100 years. The assumptions underlying the diagram are not stated, but from Griffith's previous work (1 962, Tropicul meteorology in Africa, Munitalp Foundation, Nairobi) it seems likely that they include normality of the frequency distribution of annual amounts and empirical relation between mean and variance.

The map will bz invaluable to those working on problems of land utilization and water conservation who recognise the difficulty of estimating the annual rainfall in many parts of this large area, but still must have the best opinion.

D.H. J.

Thermodynamics of clouds. By L. Dufour and R. Ilefay; translated by hl. Snlyth and '2. Beer. London (Academic Press), lOG3. Pp. xiii, 2.55; 29 Figures; 47 Tables. L-C.

The data given above, which all reviewers for Quurterly journal are asked to supply in exactly this form, are what experience normally dictates to be the vital statistics of a publication. As in another field, other more revealing features may occasionally be omitted. This book contains 664 equations ! It is essentially therefore a reference book and no researcher essaying another quantitative approach to the microphysics of the growth of cloud particles from ' embryo ' to ' germ ' to cloud droplet should fail to consult it.

The authors examine meticulously, in the first six chapters, the surface properties of a substance iiicluding the concepts of surface tension and adsorption and equilibrium states between solid, liquid and vapour phases.

Chapter VII is a particularly useful chapter in that it examines closely some approximations which tend to be taken as axiomatic in cloud microphysics : that humid air can be taken as a mixture of two perfect gases, that surface tension of a droplet is independent of the diameter of the droplet and that the effects of adsorption are negligible.

Subsequent chapters apply the concepts of the first six chapters to the meteorological problems of the initiation of condensation and the subsequent growth or evaporation of droplets and ice crystals in the atmos- phere. Considerable attention is given to the problem of homogeneous nucleation of water and ice which is of great theoretical interest but of less practical value owing to the universal presence of condensation and freezing nuclei.

The book is likely to appeal to a rather limited number, even among meteorologists, but should be available for reference in scientific libraries.

K.F.J.

Keoeeit. The story of Aurora Borealis by W. Petric. Oxford (Pergamon Press), 1963. pp. xii, 131, 23 Figs., 47 Plates. 3%.

The title of this book is the Eskimo name for the aurora. The author endeavours to present, In a form suitable for the non-scientific reader, a full account of the study of the aurora, beginning with history, instru- ments and descriptions of auroral forms and leading finally to modern ideas on the interaction betwesn solar plasma and the geomagnetic field. This is a difficult task and it is doubtful if he succeeds in it.

A reader, approaching the subject for the first time, may find the early chapters diffuse and disappointing, and the later chapters rather heavy going. The best portion of the book is that concerned with the author's own subject of research, the spectrum.

The book is well produced and copiously illustrated. J.P.

Heat trutufer in the soil. By A. F. Chudnovskii, translated from Russian. Jerusalem (Israel Programme for Scientific Translations, Sivan Press) 1st Ed., 1962. Pp. iv, 164; 41 Figures; 17') References; 13 Tables. ,Q 4s. Od.

A. F. Chudnovskii is a leading Russian authority on micrometeorology and soil physics who has worked in Leningrad at the Institute for Physics and Agriculture and at the Central Geophysical Observatory. His book on soil heat transfer, originally published in 1948, was translated in 1062.

370 REVIEWS

The review copy is a second impression (1(%3) suggesting either a small first printing to sound the market, or a surprising demand for a book now 16 years old. (“ The problem of evaporation remains in a very back- ward state, both where theory and method of investigation are concerned,” p. €9). Much work on the physics of soil temperature has been published during this time and a full account of research by van Wijk‘s group at Wageningen has recently appeared in book form.

From an introductory discussion on surface heat balance and its instrumentation, the text proceeds to theoretical analyses of heat exchange in the air (after Laikhtman) and in the soil. The measurement of sod thermal properties is discussed at length. By measuring temperature after introducing an instantaneous or isothermal heat source, thermal conductivity and diffusivity can be derived theoretically. In the laboratory, determinations by seven different methods show surprisingly close agreement. The next section discusses the dependence of thermal properties on the mineral and mechanical composition of soil, on temperature, and on humidity. The variation of conductivity with moisture content is explained in terms of the relative con- ductivity of water and soil material without reference to heat transfer in the vapour phase. There is a highly mathematical attempt to predict temperature variation in a soil whose diffusivity varies exponentially with depth: and a final chapter considers practical applications with special reference to forecasting night minimum temperatures.

In the original, this may well be a valuable text for the Russian soil physicist or engineer, but two things make it difficult to read in English : a staccato style, and dull typography. Like other translations from this source, only one type face is used in the text and the equations are printed in heavy black type often verging on the illegible.

J.L.M.