80 Scientific Intelligence. 



6. Gravity Research: Determinations of Gravity with half- 

 second Pendulums on the Pacific Coast, in Alaska and at 

 Washington, D. C, and Hobohen, JV. J.; by T. C. Mendenhall. 

 57 pp. Washington, 1892, (U. S. Coast and Geodetic Survey), 

 Appendix no. 15. Report for 1891. — Professor Mendenhall dis- 

 cusses here the new half-second pendulum and describes the use 

 at several stations, showing the high degree of accuracy obtain- 

 able with it. It is also shown that the free pendulum has a very 

 important use as a time standard. 



7. The Colors of Cloudy Condensation, by Prof. Carl Barus. 

 pp. 488-521. Reprinted from the American Meteorological Jour- 

 nal, March, 1893.— This interesting article is a full discussion of a 

 subject which the author presented briefly in the February num- 

 ber of this Journal (page 150.) 



8. Outlines of Forestry ; or the elementary principles under- 

 lying the Science of Forestry. Being a series of Primers of 

 Forestry; by Edwin J. Houston. 254 pp., Philadelphia, 1893. 

 (J. B. Lippincott Co.). — There is certainly a most urgent call for 

 enlightenment throughout this country in regard to the preserva- 

 tion and wise use of our forests, and a little book like the one in 

 hand, which presents the whole subject in so popular a form as to 

 appeal to all readers, should not fail to accomplish much good. 



9. Naples Zoological Station. — Attention is called to the 

 announcement in the advertising sheet, by Prof. Agassiz, that 

 applications will be received from candidates who desire to 

 occupy the table at the Naples Zoologieal station, placed at the 

 disposal of the faculty of the Museum of Comparative Zoology 

 at Cambridge from October, 1893. 



10. Krantz's Catalogue of PocJcs.—Dr. Krantz of Bonn has 

 recently issued an extended catalogue containing: first a system- 

 atic list of rocks arranged by Dr. W. Bonhus and Dr. Pohlig with 

 literature references; also lists of special collections arranged 

 according to particular subjects, and finally a catalogue of thin 

 sections of authentic specimens in large numbers. 



11. A Manual of Machine Drawing and Design, by David 

 Allan Low and Alfred William Bevis. 367 pp. 1893, London 

 and New York, (Longmans, Green & Co.). — Students in mechan- 

 ical engineering will find this Manual of great assistance. The 

 various parts of machines of many kinds are described here with 

 great fullness of illustration and exactness of statement, from the 

 simplest form to the triple-expansion engine. Whether the sub- 

 ject is screws, bolts and nuts or the most complex boilers, the 

 treatment is throughout admirably thorough and practical. 



12. The Hawks and Owls of the United States in their Relation 

 to Agriculture. Prepared under the direction of Dr. C. Hart 

 Merriam, Ornithologist, by A. K. Fisher, M.D. 210 pp. Wash- 

 ington, 1893, (Government Printing Office.) — A handsomely 

 illustrated work giving descriptions of the various hawks and 

 owls known in the United States. Particular attention i s given 

 to the examination of the stomachs of many of the birds as show- 

 ing the part they play in destroying insects, rodents, etc. 



