and T. I. Shaw indicates that cirri of the ACu type, in the form of waves, may form as a consequence of a decrease of pressure in the substratosphere.

Privatdozent S. Bastamov.

Rozhdestveno.
August 1918.

Calculation and Measurement of Self-Induction and Capacitance

(W. H. Nottage. The calculation and measurement of inductance and capacity. London, 1917).

The enormous theoretical and experimental material on the calculation and measurement of self-inductions and capacitances, accumulated over many years in physical and technical journals and very heterogeneous in quality, has long needed critical treatment and systematic compilation. Nottage’s book satisfies this need to a considerable extent, being a fairly complete collection of the formulas and circuits proposed up to recent times (1916).

Unfortunately, the author has confined himself only to comparing final results, without giving derivations and, what is especially regrettable, without always indicating the degree of accuracy of the formulas. There is also no critical comparison of the methods of measurement. In this respect the book falls considerably short of the corresponding surveys in the books of Henning and Eccles. The tables and graphs necessary for practical use of the formulas are not always provided; instead, references are given to the corresponding journal literature. This circumstance considerably deprives the book of practical independence.

Quite a few pages are devoted purely to radiotelegraphic measurements and calculations: there is given, for example, a series of noteworthy formulas for calculating the capacitance of radiotelegraphic networks, proposed recently by Howe. In the last chapter various standards and instruments necessary for precise measurements are described: Duddell’s alternator, the alternating-current “megohaemeter” of Fleming and Dyke, galvanometers, electrometers, telephones, etc.

There are some regrettable omissions; for example, one of the most general and exact formulas for calculating the self-induction of Rayleigh’s concentric coil is absent.

In any case, however, the book fills a substantial gap in the series of reference books needed by every physical and electrical-engineering laboratory.

S. Vavilov.