REVIEWS 137

As an example of the ' rules,' one may be quoted (taken from a different part of the work) : Rule 15 : Given the following conditions during the summer half-year in the middle latitudes of the

northern hemisphere on the continents in areas which are not too markedly affected by orographic disturbances: (a) a drop in the daily mean temperature of at least 4°C is followed for two successive days by a simultaneous

rise of the daily mean temperature and of the atmospheric pressure, from evening to evening, and (b) the pressure rise is concurrent with overcast skies for at least 12 hours in succession.

We can expect with a high degree of probability that mainly dry weather will prevail during the following 5 days, provided that the temperature lies below its normal value on the last day of the temperature drop, that the pressure, reduced to sea level, amounts to at least 1020.0 mb on the second evening of the simultaneous pressure and temperature rise, and that no sharp pressure changes of either sign have occurred immediately before these last two days.

These examples of the method and the results should enable the reader to decide how far the work will repay his attention.

J.M.C.

Hundbuch der Geophysik, Bd. VIII : Physik der Atmosphare I , Chapters 12, 13, 14. Edited by F. Linke and Pp. 174; 65 Figs.; 31 Tables, 1 colour plate.

These three chapters of the Hundbuch form a coherent group describing all the physical processes of atmospheric refraction, reflection, scattering and absorption in the optical region of the spectrum. With the exception of a brief mention of the ' green flash ' by R. Meyer in Chapter 13 and passing reference to the colour of the sky and the ' purple light ' by F. Volz in Chapter 14, the chapters are almost entirely concerned with principles and it is to be assumed that there will be further detailed chapters, of similar standard, on the actual atmospheric optical phenomena. If this is so, then this new edition of the Handbuch will be a document of exceptional value, for this particular sample is exhaustive, systematic and (as far as the reviewer's German allows him to judge) well written.

F. Lauscher writes on ' Optik der Gewiisser ' and treats, very fully, problems of refraction and reflection at flat, curved, and wavy water surfaces, and also the complicated question of internal scattering in water. Brief mention is made of instruments for measuring in natural waters and some results are given. The theory is excellent as far as it goes, but when faced with the results of field measurements one finds that it does not go very far and the treatment becomes empirical.

Chapter 13 is a long chapter (52 pp.) by R. Meyer, entitled ' AtmosphZrische Strahlenbrechung ' which deals essentially with three problems : refraction of stellar images by a stratified atmosphere with a uniform temperature gradient (the problem of accurate astronomical positional measurements) ; effects of irregular density changes (the problem of astronomical ' seeing '); the height of the horizon and mirages. This con- centration on the optical region means that only refractive index changes due to temperature changes are considered. An opportunity is certainly missed of presenting a unified treatment embracing the effect of water vapour on refraction of very high frequency radio and the effect of the ionosphere on medium and low frequency radio. These problems are entirely analogous and, for example, the recent resurgence of interest in problems of atmospheric ' seeing ' is, in this country at any rate, directly connected with the development of ionospheric measurements on winds and turbulence.

Chapter 14 is by F. Volz and is entitled ' Optik der Tropfen; Abschnitt I : Optik des Dunstes.' The whole section on optics of droplets is going to be a remarkable compilation, for this part alone contains 75 pp. and has about 160 references. As a sign of the extent to which this small part of physical meteorology has grown, it may be pointed out that Dr. Volz scarcely touches on the theory of scattering and goes almost straight to the results, missing out all the work on this theory beautifully presented in his Doctoral Thesis by Van der Hulst. From the point of view of a specialist this is perhaps a pity, but Dr. Volz is probably quite correct in his choice of presentation. All the references are given and the descriptive matter is easily readable. Further excursions into theory would have resulted in a most unwieldy article.

Apart from the lack of detailed theoretical treatment Dr. Volz's article embraces the subject in all its aspects both theoretical and observational. Considerable use has to be made of diagrams which are com- plicated and at first sight confusing, although careful study shows that their meaning is in fact quite clear. It is a very surprising thing that publishers of the reputation of Gebruder Borntraeger should be content with a wide variety of printing in the diagrams, and including some examples of most unprofessional free-hand.

All criticisms however are unimportant when compared with the completeness and authoritative nature of the articles. The completed volumes will undoubtedly be a necessity for all institutions and many research workers.

F. Moller. Berlin (Gebruder Borntraeger), 1955-56. NP.

Chapter 12 is perhaps the least important of the three.

This is a rather typical geophysical topic.

R.M.G.

The sun. The solar system, Volume 1. Edited by Gerard P. Kuiper. University of Chicago Press, 1953. Pp. xix, 745. $12.50 (Cambridge University Press, 94s.).

This book on the sun is the first result of the great enterprise of Professor Kuiper and the Chicago University Press to give a systematic and comprehensive account of the solar system. The series of 4 volumes