352 Scientific Intelligence. 



deposition of parallel plane layers ; new faces are constantly 

 developed : since these succeed one another per saltum they 

 doubtless obey the law of rational indices, though not that of 

 simple rational indices. From the mutual inclinations of these 

 vicinal faces it is possible to calculate with absolute accuracy 

 the angle of the faces to which they symmetrically approximate. 

 This angle is found to be that of the regular octahedron 70° 8 if. 

 The octahedron angle of alum is not, therefore, as appeared from 

 the observations of Pfaff and Brauns, subject to any variation.- — 

 Nature, vol. 1, p. 411, August 23, 1894. 



III. ASTKONOMY. 



1. Verzeichniss der Elemente der bisher berechneten Cometen- 

 bahnen, etc., by Dr. J. G. Galls. 8°, pp. xviii, and 316. Leipzig, 

 1894. This volume is a new edition by the veteran astronomer 

 of the work published by him in 1847 and later in 1863. The 

 earlier edition was a continuation and completion of the like Cat- 

 alogue of Olbers in 1823. The first half of the present volume is 

 a tabular catalogue of all computed elements of the cometic orbits 

 up to the present year. The second half consists of historical, 

 descriptive and bibliographical notes upon the several comets. 



2. Gesammelte Werke von Heineich Hertz, Band III/ Die 

 Prinzipien der Mechanik in neuene Zusammenhange dargestellt. 

 8°, pp. xxix, 312. Leipzig, 1894, (Barth.) — This volume of the 

 collected works of the greatly lamented physicist contains in the 

 preface by von Hemholtz a generous tribute to Hertz. The 

 work consists of two books, 1st, the geometry and kinematics of 

 material systems, and 2d, the mechanics of material systems. 

 The first part was in completed form, but the second the author 

 intended to rework but was prevented by his illness which 

 proved fatal. He placed his manuscript in the hands of Ph. 

 Lenard under whose care the present volume is published. 



IV. Miscellaneous Scientific Intelligence. 



1. The American Association for the Advancement of Science. 

 — The retiring President, William Harkness, delivered the address 

 at the opening of the Brooklyn meeting in August, " On the 

 Magnitude of the Solar System," (this Journal, pp. 230-250). 

 The subjects of the vice-presidential addresses were as follows : 

 Section A, " Binary Stars," by G. C. Comstock ; section B, 

 "Obscure heat as an agent in producing expansion and contrac- 

 tion of metals under air contact," by William A. Rogers; section 

 C, "The Battle with fire," by Thomas H. Norton; section D, 

 " Paradoxes in the resistance of materials," by Mansfield Merri- 

 man ; section E, "The Niobrara Chalk," by Samuel Calvin; 

 section G, " The Evolution of the Hepatica?," by Lucien M. 

 Underwood ; section H, " Human faculty as determined by Race," 

 by Franz Boas; section I, "A stable Monetary Standard," by 

 Henry Farquhar. 



