Septembee 13, 1907] 



SCIENCE 



341 



of these the historical method of presenta- 

 tion is fundamental. 



S. B. Slocum 

 University of Cincinnati 



SCIENTIFIC BOOKS 

 A Student's Manual of a Laloratory Course 



in Physical Measurements. By Professor 



W. C. Sabine. Ginn & Co. 1906. 8vo, 



pp. 97. 

 A Text-hooh of Practical Physics. By W. 



Watson. London, Longmans, Green & Co. 



1906. 8vo, pp. 626. 



Elementary physical laboratory work in 

 American universities has to fulfill tvFO re- 

 quirements, namely, to complement the first 

 lecture course in general physics and to teach 

 accuracy of observation. While it is desirable 

 that the number of experiments to be per- 

 formed should not be too limited, the character- 

 istic value of physics as a culture study lies 

 in the training of accuracy of expression and 

 observation. In order to enable the student 

 to perform a sufficiently large number of ex- 

 periments — which is unfortunately often made 

 the test of ability — and to give him the neces- 

 sary training in accuracy, it has become the 

 custom to describe only those exercises which 

 he is expected to perform, and avoid a possible 

 " waste of time " by rather minute descrip- 

 tions of apparatus. 



The selection of a few out of a large num- 

 ber of instructive experiments is always a 

 difficult task and will lead to a different 

 choice, according to the tastes of the author 

 and the equipment of the school in which the 

 book is to be used. 



Sabine's well-known manual which has now 

 appeared in its second edition shows this 

 elasticity of selection in the omission of many 

 exercises found in the former edition and the 

 introduction of several new ones. Their num- 

 ber has been reduced from about seventy to 

 thirty. Mechanics has practically remained 

 unchanged. In sound a qualitative experi- 

 ment, " Quality by the manometric flame," 

 has been added. All the former experiments 

 in heat have been omitted and a single one 



substituted for them, namely, " the determina- 

 tion of the mechanical equivalent of heat." 

 Without questioning the great importance of 

 this exercise it seems to the reviewer that 

 some of the discarded experiments, as " specific 

 heat, heat of fusion, or expansion " are better 

 adapted, at least for an elementary course 

 which is expected to teach only the rudiments 

 of physical manipulations. In light also im- 

 portant changes have been made. " Equiva- 

 lent focal length of compound lenses " takes 

 the place of several exercises on radii of 

 curvature and focal length of mirrors and 

 lenses. "Wave-length of light by Newton's 

 rings and the diffraction grating," also " Eota- 

 tion of polarized light " are new. In the elec- 

 trical part a good descriptive chapter on 

 galvanometers adds much to the value of the 

 book. The work with cells (internal resist- 

 ance, different arrangement of cells, etc.) has 

 been considerably condensed and an experi- 

 ment with the dynamo added. 



On the whole the changes made for the new 

 edition are good; each exercise illustrates an 

 important principle and a repetition of the 

 same in other parts of the book has been care- 

 fully avoided. The instructions given for 

 each experiment are more specific than in the 

 first edition, but this has not been carried so 

 far as to prevent a certain independence of 

 the student and a possible variation of the 

 apparatus used in the course. 



Watson's " text-book " is of an entirely dif- 

 ferent character. It is more of the nature 

 of . Kohlrausch's " Leitf aden " and contains 

 nearly 200 experiments. An introduction of 

 forty pages treats of general methods used in 

 the reduction and discussion of the results of 

 physical measurements, and an appendix of 

 twenty pages contains short practical infor- 

 mation as to glass blowing, work with fused 

 quartz, silvering glass, mounting of cross 

 wires in telescopes and microscopes and the 

 use of manganin wire for the construction of 

 standard coils. 



The book is intended for students who 

 " have already spent a little time in the labo- 

 ratory," and for such it is an excellent refer- 



