480 Scientific Intelligence. 



were — 0-71^, — 0-15-", + 0-24<", and 4-0-44'" respectively, The 

 curve representing these data passes through a minimum at about 

 — 80° C. and is perfectly "smooth " at higher and lower temper- 

 atures. The equation of the curve is given as " l t = l [l + 0-362 

 X lO -6 . t + 0-001813 X 10" 6 . t 2 — 0-00000340 X lO" 6 . Z 3 ]." The 

 investigators point out the danger associated with the assumption, 

 often made, that the expansion of fused silica is negligible. In 

 particular, this assumption caused certain data given by Linde- 

 mann to deviate from the correct values by as much as 30 per 

 cent. Since the work on quartz glass was carried out at the 

 Bureau of Standards at Charlottenburg it is doubtless very trust- 

 worthy. — Verh. d. deutsch. physik. Gesellsch., No. 1, p. 1, 1914. 



h. s. u. 



10. Physics for Technical Students. Mechanics and Heat ; 

 by William Ballantyne Andekson. Pp. xi, 349; 153 figures. 

 New York, 1914 (McGraw-Hill Book Co.).— This book empha- 

 sizes the practical applications of the subjects discussed because 

 it is designed primarily to meet the needs of classes in Agricul- 

 ture and Engineering. With this end in view special care has 

 been given to the text figures, which are, without exception, well- 

 drawn and clearly printed. The author says: " Wherever pos- 

 sible, every principle involved in the text is brought up again in 

 a problem; so that in working all of the problems a review of 

 practically the entire book is obtained." " For a complete course, 

 the text should be accompanied by lectures and laboratory work." 



The subject-matter is divided into three Parts treating respec- 

 tively of Mechanics (133 pages, 124 problems), Properties of 

 Matter (78 pages, 43 problems), and Heat (116 pages, 36 prob- 

 lems). (Answers to the problems are not given.) 



The author's style is clear, logical and attractive. The topics 

 discussed are presented in a thoroughly scientific manner so that 

 the usefulness of the volume should not be restricted to purely 

 technical classes. "More space than usual has been devoted to 

 the treatment of Force, Torque, Translatory Motion, and Rotary 

 Motion." On the other hand, the text is enhanced by not being 

 encyclopedic. Unusual care has been taken to minimize errors 

 of all kinds and the book makes such a pleasing impression that 

 it merits a successful future. u. s. tr. 



11. Natural Sources of Energy ; by A. H. Gibson. Pp. viii, 

 131; 17 figures. Cambridge, 1913 (University Press). — This 

 little book is devoted to a discussion of the world's energy prob- 

 lem and the possibilities of its solution. A short chapter on the 

 transformation of energy is followed by three chapters on the 

 utilization of fossil fuels, of solar heat, and of vegetation for 

 power purposes respectively. Attention is then turned to a con- 

 sideration of the internal heat of the earth and of various natural 

 sources of power, such as water, tidal, and wind power. It is 

 thus seen that the author wisely avoids entering the highly specu- 

 lative field afforded to the fertile imagination by the recent dis- 

 coveries in the domain of molecular physics. The maps showing 

 the distribution over the surface of the earth of regions of intense 



