562 Scientific Intelligence. 



tive was compounded of separate strips carefully pasted side by- 

 side on one sheet of paper. It is thus seen that Seetnann's method 

 differs from the more common arrangements in several respects. 

 For example, it is customary to endeavor to obtain good defini- 

 tion by making the distance from the plate to the " reflecting " 

 surface of the crystal equal to the distance between the slit and 

 this crystal surface. Also, the cnstal is usually rotated while a 

 photographic film, curved to the proper radius, is kept fixed with 

 respect to the bulb and slit. — Phys. Zeir.se/tr., Sept. 15, 1914, 

 p. 794. h. s. u. 



10. The Spectroscopy of the Extreme Ultra-violet ; by Theo- 

 dore Lyman. Pp. v, 135, with 15 figures and 1 plate. London, 

 1914 (Longmans, Green and Co.). — The first Part of this book 

 (pages 1 to 28) deals with the ordinary ultra-violet, which is 

 defined as comprising the region between A4000 and A/2000. The 

 rest of the text, Part II, is devoted to a detailed account of the 

 Schumann region, A.2000 to X900. The five chapters of the second 

 and main division of the volume pertain respectively to the appara- 

 tus and methods of investigation in the extreme ultra-violet, 

 absorption of solids and gases, emission spectra of gases, emission 

 spectra of solids, and to photo-electric and photo-abiotic phe- 

 nomena. 



The author has been able to present the subject-matter in a 

 very clear, concise manner because of his extensive and fruitful 

 experience in investigating the Schumann region with his specially 

 designed grating spectrograph. The style is far more satisfactory 

 than is often the case with monographs of this general character 

 in that the author discusses his own brilliant work with dignified 

 modesty, and does not neglect the historic side of the subject and 

 the results obtained by others. It is almost needless to state that 

 the text abounds in important spectroscopic data. At the end of 

 the volume, seventeen tables of wave-lengths are given. These 

 are followed by a general bibliography, a list of papers by V. 

 Schumann, an appendix on the sensitizing of plates, and subject 

 and author indices. The book is undoubtedly an important and 

 authoritative contribution to the special field to which it relates. 



h. s. u. 



11. Elementary Electricity and Magnetism; by Wm. S. 

 Franklin and Barry Macnutt. Pp. viii, 174, with 152 figures. 

 New York 1914 (The Macmillan Co.). — This little volume is 

 designed to be used as a text-book in colleges and technical 

 schools. The kind of study of electricity and magnetism contem- 

 plated by the authors may very properly be called " electro- 

 mechanics." In other words, the subject-matter is presented in 

 such a manner as to be independent of any considerations con- 

 cerning the nature either of the physical action which leads to 

 the production of electromotive force in a voltaic cell or d}-namo, 

 or of the physical action which constitutes an electric current in 

 a wire, or of the disturbance which constitutes a magnetic field, 

 or of the stress in an electric field. The first chapter deals with 



