124 



THE POPULAR SCIENCE MONTHLY. 



heating and efficient ventilation of the build- 

 ings. It begins with the consideration of 

 the site and the digging of the feell, and 

 closes with the elevations and finishings of 

 the schoolhouses. An article on log school- 

 houses is added. Circular Xo. 6 is a state- 

 ment of the working of the English educa- 

 tion act of ISVO in districts outside of cities, 

 prepared for the department, by Mr. Henry 

 W. Hulbert. 



Electric Lighting by Incandescence. By 

 W. E. Sawyer. New York: D. Van 

 Nostrand. 1881. Pp.189. Price, $2.50. 



In these chapters Mr. Sawyer has given 

 a resume of the present condition of electric 

 lighting by incandescence, describing the 

 chief apparatus that has been so far de- 

 vised. He begins his exposition with a con- 

 sideration of the various electric generators, 

 as these necessarily are at the foundation of 

 any system of electric lighting. Of these 

 the two important classes are those of the 

 Gramme type, in which he includes those of 

 Maxim and Brush ; and those of the new 

 Siemens type, in which he places his own 

 and Edison's. The Wilde,. De Meritens, 

 and Lontin machines are also described, 

 the first being characterized as the " germ 

 of a perfect generator," in that in it the in- 

 tensity of the magnetic field is uninfluenced 

 by the resistance of the external circuit, 

 and a larger part of the entire current can 

 therefore be used than in accumulative ma- 

 chines. The review of incandescent lamps 

 includes those of Starr and King, Lody- 

 guine, Konn and Kosloff, Bouliguine, Fon- 

 taine, Farmer, Sawyer, Edison, and Maxim, in 

 which the carbon is protected from the at- 

 mosphere, and those of Reynicr and Wer. 

 dermann, in which it bums in the air. Of 

 the former, only the last three are regarded 

 as practicable lamps, and of these the Max- 

 im is considered as, in all essential particu- 

 lars, a duplication of that of Edison. With 

 regard to the duration of the carbon, Mr. 

 Sawyer holds that the hope of making it 

 permanent is chimerical, as no material will 

 stand the strain to which an incandescent 

 conductor is subjected, and that the part of 

 wisdom, therefore, is to provide for its re- 

 newal. In treating of the division of the 

 current, four systems are considered the 

 series, the multiple, the multiple-series, and 

 the series-multiple system. In the first, the 



lamps are strung one after the other upon 

 one wire ; in the second, each lamp is hung 

 on a branch between two parallel wires ; in 

 the third, several lamps are placed upon a 

 branch ; and, in the last, groups or bunches 

 of lamps are strung upon one wire. For 

 a large number of lamps, Mr. Sawyer con- 

 siders the first arrangement impracticable, 

 and the last, which he has adopted, the 

 most desirable. Regarding the cost of in- 

 candescent lighting, the conclusion is reached 

 that it is not more than one seventh of that 

 of gas for equal light, while the cost of 

 plant, repairs, etc., will be much less. As to 

 the future of incandescent lighting, and its 

 relations to other forms of illumination, 

 Mr. Sawyer expresses himself as follows : 

 " The application of electricity to public and 

 private illumination is a realization of the 

 near future no longer to be questioned. It 

 is not probable, however, that electricity 

 will ever entirely supersede gas ; indeed, it 

 does not appear that illuminating gas has 

 materially affected the consumption of illu- 

 minating oils. There is room, and will doubt- 

 less continue to be room, for all methods 

 of artificial lighting, and it is not likely 

 that, for many years to come, we shall wit- 

 ness anything more than the extensive use 

 of electricity public buildings and private 

 residences, streets, and squares better illu- 

 minated than at present, and the new form 

 of light keeping pace with the progress of 

 older and well-tried institutions." 



The Cause or Color among Races and the 

 Evolution of Physical Beauty. By 

 William Sharpe, D. D. New edition, re- 

 vised and enlarged. New York : G. P. 

 Putnam's Sons. 1881. Pp. 36. Price, 

 75 cents. 



The author's views are partly based on 

 observations made among the different races 

 of India. Ho supposes that lighter-colored 

 peoples are developed from darker colored 

 ones by a process of evolution which cor-r 

 responds with the advance of civilization, 

 and is promoted by the increasing habit of 

 wearing clothing. The qualities which give 

 a dark color to the skin are those which 

 are necessary to preserve it against the in- 

 clemency of the elements. As clothing be- 

 comes more general, fuller, and more regu- 

 larly worn, they become less important for 

 protection, and are finally nearly obliterated. 



