International Monographs Research Articles

Comparison of the Modified Method of Averaging and the Two Variable Expansion Procedure

Comparison of the Modified Method of Averaging and the Two Variable Expansion Procedure

Book Reviews : Nutritional Factors and Enzymological Dis turbances in Animals, by C. H. Gallagher, D.V.SC., PH.D. International Monographs: aspects of animal and human nutrition, consultant editor André Voisin. 181 pp. CROSBY LOCKWOOD & SON LTD. London, 1964. £2 [U/1964

Book Reviews : Nutritional Factors and Enzymological Dis turbances in Animals, by C. H. Gallagher, D.V.SC., PH.D. International Monographs: aspects of animal and human nutrition, consultant editor André Voisin. 181 pp. CROSBY LOCKWOOD & SON LTD. London, 1964. £2 [U/1964

International collaboration in the study of varieties of lettuce

A team of lettuce specialists from England, France, Germany and Holland studied the world's lettuce varieties in 1954 and 1955. The number of real varieties was found to be about 130. (For these more than 500 names are in use.) In addition to colour photographs of the 130 varieties, detailed descriptions of their characters and cultural possibilities were made. It is intended to publish the compiled material in the form of an international monograph of lettuce varieties.

Radio Transmission Lines and Wave Guides

THE problem associated with the applications of radio waves to communication, location or navigation is to generate high-frequency alternating currents and convey them from the source to an antenna system which radiates the waves into space. The connecting link between the source and the radiator is termed a transmission line, and for moderately high radio frequencies may comprise a system of two parallel wires, or a coaxial cable or some elaboration of these. At the very high frequencies corresponding to wave-lengths less than a few centimetres in length, this transmission line system takes the form of hollow conductor of circular or rectangular cross-section termed a wave guide. The two books under review deal respectively with transmission lines and wave guides as used in modern radio frequency technique. Electrical Transmissions in Steady State By Paul J. Selgin. (Radio Communication Series.) Pp. ix + 427. (New York and London: McGraw-Hill Book Co., Inc., 1946.) 25s. The Physical Principles of Wave Guide Transmission and Antenna Systems By Prof. W. H. Watson. (International Monographs on Radio.) Pp. xiv + 208. (Oxford: Clarendon Press; London: Oxford University Press, 1947.) 20s. net.