78 Scientific Intelligence. 



8. Deflection* by Electrostatic and Magnetic Fields of Radium 

 B after Recoil from Radium A. — These deflections have been 

 measured — the electrostatics, by Sidney Russ and Waltbe 

 Makowkr; the magnetic by W. Makowbe and E.F.Evans, 



and estimations of the value of ' and the atomic weight of 



in & 



radium were made. The value of 194 was obtained for the latter, 



which the authors regard as good agreement with the theoretical 



value 214.— Phil. Mag., No. 15, 1910, pp. 875-886. j. t. 



9. Energy Distribution of Diffraction Gratings. — Professors 

 Augustus Trowbridge and It. W. Wood continue their investi- 

 gations on the energy of distribution irom definite forms of 

 grooves — wedge shaped — in gratings with few rulings which are 

 called echelettes. They show that these gratings give the highest 

 resolving power that has yet been brought to bear upon the 

 infra-red. — Phil. Mag., Nov. 1910, pp. 886-901. j. t. 



10. Modification in Magnetic Fields of Lines of the Light 

 emitted by the Electric Spark. — G. A. Hemsalech finds that mag- 

 netic fields modify the intensity of light. On the sun such fields 

 may produce a diminution of light, showing thus an apparent 

 absorption of light coming from the photosphere and a reinforce- 

 ment of certain lines in the solar spots. — Comptes Hendus, Nov. 

 21, 1910, pp. 938-941. J. T. 



11. Electric Motors ; by Henry M. Hobart. Pp. xxiv, 748, 

 with 798 illustrations. New York, 1910 (The Macmillan Co.). — 

 This is the second edition, entirely rewritten and enlarged, of a 

 volume which first appeared in 1904. It treats the theory and 

 construction of continuous, polyphase and single phase motors; 

 the section on the latter accounting in large part for the increased 

 size of the present edition. A useful table of the properties of 

 copper wire for standard wire gauge is given in the Appendix. 



D. A. K. 



II. Geology and Natural History. 



1. Grundzuge der Palaontologie ; by Karl A. von Zittel, 

 1. Abteilung, third edition, revised by F. Broili, 1414 text figs., 

 607 pages with an index. Munich, 1910 (Oldenbourg). — This 

 well known German text-book, the classic of Invertebrate Paleon- 

 tology by a great past master, is here revised by one of his 

 students. The reviser has added about 70 new figures and on 

 many of the old ones letters have been affixed permitting of 

 more direct descriptions of the structural parts. There are 

 about 90 pages of new matter over the first edition, and about 

 50 pages more than in the second edition. 



The revision and additions are chiefly important in matter of 

 detail and the classification adopted is practically that of the 

 former editions. Even Treptostotnata Bryozoa or the monticuli- 



