66 



NA TURE 



[July 15. 1909 



PHYSICS FOR THE LECTURE ROOM AND 

 LABORATORY. 



{i) The Elements of Electricity and Magnetism. A 

 Text-book for Colleges and Technical Schools. By 

 Prof. W. S. Franklin and Barry Macnutt. Pp. 

 viii + 351. (New York: The Macmillan Co.; 

 London: Macmillan and Co., Ltd., 190S.) Price 

 ~s. net. 



(2) .4 Short University Course in Electricity, Sound 

 and Light. By Dr. Robert A. MiUikan and J. 

 Mills. Pp. v + 389. (Boston and London : Ginn 

 and Co., n.d.) Price Ss. 6d. 



(3) Naturlehre fiir hohere Lehranstalten auf Schuler- 

 iibungen gegrundet. By Dr. Friedrich Danneman. 

 Teil ii. Physik. Pp. vii + 204. (Hanover and 

 Leipzig: : Hahnsche Buchhandlung, 1908.) Price 

 3. So marks. 



(4) The Elementary Theory of Direct Current Dynamo 

 Electric Machinery. By C. E. Ashford and E. \V. E. 

 Kempson. Pp. vii+120. (Cambridge: University 

 Press, 1908.) Price 3s. net. 



(5) Electrical Laboratory Course for Junior Students. 

 By R. D. Archibald and R. Rankin. Pp. vi + 9s. 

 (London : Blackie and Son, Ltd., 1908.) Price 

 Ii". bd. net. 



(O'T'HE order in which the elements of electricity and 

 -L magnetism are presented in the first volume 

 under notice is :— (a) Electric current; (b) magnetism; 

 (c) electrostatics; (d) electric waves. This order is one 

 which does not make the exposition perfectly happy. 

 Thus it does not seem natural when it is found neces- 

 sary to refer provisionally to the measurement of cur- 

 rents by their magnetic effect (p. 7) prior to any state- 

 ment as to how magnetic effects themselves are 

 measured. Surely the natural order is to take mag- 

 netism before considering the electric current, even 

 though it may be preferred to deal with both before 

 considering the phenomena of electrostatics. The 

 author passes naturally and easily to the exposition 

 of the last-named phenomena, and as many prefer 

 this order this portion may certainly be commended to 

 them. 



The author is convinced that " elementary science 

 instruction must be made to touch upon the things 

 of everyday life if it is to be effective." This sentence 

 may be taken as the keynote to the entire book. Thus 

 electric resistances are usually represented as electric 

 lamps. Those who are accustomed to abstract think- 

 ing may smile at these concrete representations; but 

 it must be remembered that this is only an elementary 

 book, and it must be admitted thai much of the diffi- 

 culty which many junior students feel is connected 

 with the unreality of the subject as it appears to them. 

 We commend the book for endeavouring, in this and 

 other ways, to make the subject more real than it 

 usually is. 



More attention is given than is customary in an 

 elementary course to phenomena connected with recent 

 discoveries, such as kathode rays, radio-activity, electric 

 waves, &c. We conclude that in America a junior 

 course is in some respects more advanced than with 

 MS. This remark applies most to the chapter on elec- 

 NO. 2072, VOL. 81] 



trie waves, and to the appendix on ship's magnetism. 

 Both these portions are very well done, though we 

 would have thought them fairly strong meat for those 

 who are making a " first systematic study of the 

 subject." However, whether a student takes them 

 in completely in his first study or not, he will be very 

 glad to find them here ready to hand when required. 



(2) The second of the volumes under review " repre- 

 sents primarily an attempt to secure a satisfactory 

 articulation of the laboratory and class-room phases 

 of instruction in physics." Expressed otherwise, it 

 consists of a description of laboratory work, each 

 experiment being preceded by as much theory as is 

 necessary to make a complete logical exposition of the 

 subject under study. We think that this plan is an 

 excellent one ; and it has been very satisfactorily 

 carried out. Of course, it will be understood that the 

 theoretical part is not sufficient to replace a text-book 

 dealing specially with the theory. 



Although electrostatics is introduced in the first 

 chapter, electric capacity is not defined until later, 

 when it can be measured by means of a ballistic gal- 

 vanometer. There may be something to be said for 

 this, but we think that the course of experiments 

 would be considerably improved and the student would 

 get a more vivid idea of what capacity is if experi- 

 ments were added on parallel plate condensers used 

 along with a gold-leaf electroscope or an electrostatic 

 voltmeter. 



In sound, a series of experiments on diffraction is 

 included. The experiments on light begin with 

 diffraction, a fact which prepares us for the exclusive 

 use of the wave-method in proving the general 

 phenomena of reflection and refraction. The final 

 chapter is on radio-activity, and contains some simple 

 experiments on uranium and thorium salts. The book 

 is altogether a most excellent manual. 



(3) We find in our third volume a well-selected series 

 of very elementary experiments in the whole round 

 of phvsics suitable particularly for school use. Though 

 the subject is dealt with satisfactorily as a rule, it is 

 not beyond criticism. The diagram of the paths of 

 rays in a microscope would be improved if the rays 

 represented as passing through the eyepiece were the 

 same as those transmitted through the objective. The 

 experiment on the " velocity of electricity " would be 

 best left out of such an elementary book ; the state- 

 ment that electricity travels with the velocity of light 

 is, of course, absurd. 



(4) We are in entire agreement with the authors of 

 this book, that in the training of an electrical engineer 

 there should be included a knowledge of the theory 

 of the subject built up logically from first principles, 

 each step being illustrated with the help of some piece 

 of machinery or practical appliance of a general and 

 simple rather than an elaborate or necessarily up-to- 

 date type. The present volume is intended to be used 

 only as a note-book accompanying a course of experi- 

 mental lectures. The authors are to be congratulated 

 on the excellence of their little manual. The diagrams 

 in particular are very carefully designed. 



(5) The last of this group of text-books covers an 

 elementary first year's evening course and part of a 



