642 



NA TURE 



[May 20, 1922 



of inspiration. Broad outlines should first be pre- 

 sented in an elementary but scientific manner. Part i 

 of this book, which is intended to be used in conjunction 

 with a theoretical text-book, aims at giving such a 

 general sketch in which new knowledge is incorporated 

 as an essential part of the course. Part 2 comprises 

 a course of laboratory work suitable for general pur- 

 poses. In an interesting preface Mr. Southerns has 

 some suggestive observations as to the methods of 

 dividing students into classes, with the view of allowing 

 the better students to undertake more advanced work. 

 Such subdivision is advocated in connexion with both 

 tutorial and practical work. The book has been well 

 thought out, and may be recommended to teachers 

 who have similar problems to solve. 



(2) In this new volume Prof. Ferry, who is known 

 as the author of a useful handbook of practical physics, 

 has placed teachers of physics under fresh obligation 

 by providing a text-book for college students " in 

 which especial emphasis is laid on the diverse relations 

 of physics to Nature, agriculture, engineering, and 

 the home. Much of the motivation and illustrative 

 material has not appeared heretofore in any text-book." 

 Even if we do not fully grasp what is impHed by the 

 term " motivation," we may admit the general accuracy 

 of this claim. A lecturer on physics in search of novel 

 or up-to-date illustrations should certainly consult this 

 volume. By studying the series of kinetoscope photo- 

 graphs of a freely falling cat and the accompanying 

 letterpress he will learn why the cat alights on its feet. 

 " The recent war has produced many highly important 

 and interesting devices, some of which are here pre- 

 sented to students for the first time." We find, for 

 example, descriptions of acoustic goniometers, based 

 on binaural hearing, for locating invisible submarines 

 and aeroplanes, and of the " radio-compass," by means 

 of which the position of a vessel at sea may be found 

 by wireless signals. 



The amount of information that has been packed 

 into these 700 pages is remarkable. But it must not 

 be supposed that this is merely a popular or descriptive 

 book ; it is a scientific treatise, and every page bears 

 evidence of the fact that it is the work of one who has 

 considered with care the theory of each subject and the 

 best method of presenting it to the student. A few 

 points of interest may be mentioned. For the familiar 

 " latent heat of fusion " the term " heat equivalent of 

 fusion " is suggested. The paragraph dealing with the 

 black-body temperature scale seems to us to make a 

 simple matter complicated by its treatment of " the 

 black-body temperature of a non-black body." There 

 seems no good reason for speaking or thinking of this 

 as the temperature of the non-black body itself ; it is 

 simply the temperature of a black body which emits 

 NO. 2742, VOL. 109] 



radiation at the same rate. Electric resistance is dis- 

 cussed before electromotive force or Ohm's law, being 

 measured by the amount of heat developed in a 

 conductor by the passage of unit current for unit 

 time. 



There are interesting chapters on the electron 

 hypothesis (including a description of the three- 

 electrode vacuum tube) and on electromagnetic waves. 

 The section on light is excellent ; the cardinal points 

 and the aberrations of lenses and lens systems are well 

 treated, as also are various optical instruments. 

 Physical optics claims attention in three interesting 

 chapters. The statement on p. 626 that it is impossible 

 to have a blue sea when the sky is overcast has been 

 contradicted recently by Prof. Raman (Nature, 

 vol. 108, p. 367). The volume contains numerous 

 solved problems in the text, and nearly 700 unsolved 

 problems with answers in an appendix ; the illustra- 

 tions deserve a special word of commendation. 



(3) Space is lacking for a full account of the high 

 ideals which have inspired the author of this manual. 

 Suffice it to say that the physics course in a modern 

 (American) high school " should proceed toward an 

 organisation of practical situations, activities, and 

 phenomena, the value of which will be recognised and 

 approved by teachers, students, parents, administrators 

 of education, and others who are responsible for the 

 work which boys and girls do in the high school " ! 

 Hence these ninety-five " projects " include the con- 

 struction of " a model of a kitchen hot- water heater " 

 {sic) ; studies of methods of heating or lighting a room ; 

 experiments on electroplating, saucepan conduction, 

 and wireless ; studies of the camera, the kerosene stove, 

 the phonograph, and the sewing machine ; and lastly 

 a section headed " automobile work " deahng with 

 carburettors, ignition systems, and the engine of a 

 Ford car. Here is a course " organised according to 

 the recognised function of education in a democratic 

 society" ! We cannot help feeling a certain amount 

 of envy of the boys and girls in the modern high school. 



(4) Messrs. Haler and Stuart have produced an intro- 

 duction to physics based on experiments which can be 

 carried out with simple apparatus. The scheme is 

 intended to cover a two-years course for technical or 

 trade schools, when two or three hours a week are 

 devoted to the subject. Questions and numerical 

 exercises are plentiful. It is scarcely logical to say that 

 the absolute zero of temperature would be reached 

 at -273°C. when the only scale of temperature that 

 has been described is that of the mercury thermometer. 



(5) Mr. S. E. Brown has prepared a useful course on 

 light to occupy two terms for pupils about fourteen 

 years of age. There are plenty of experiments and 

 illustrations, and the Barr and Stroud range-finder is 



