376 Scientific Intelligence. 



mountains, which are composed of Pre-Cambrian rocks. Sloping 

 from this center are sedimentary strata made up largely of 

 Ordovician limestones, which were capped by a shale. The lime- 

 stones, lying between two impervious formations, formed an 

 artesian basin. It is believed that the metal content of the ore 

 bodies originally existed in a disseminated state throughout the 

 limestones and was gradually dissolved by the underground waters 

 and transported by them to the open ground which lay at the 

 base of the overlying shale formation and there deposited again 

 in the ore bodies. w. e. f. 



11. Meteorites: Their structure, composition and terrestrial 

 relations; by Oliver Cummings Farrington. Pp. x, 233; 65 

 figs, and frontispiece. Chicago, 111., 1915 (Published by the 

 author). — The subject of meteorites has been one which has 

 excited great interest, both on the popular and scientific side, 

 ever since the nature and origin of the " falling stones " was first 

 determined. This is explained by the general uncertainty as to 

 their source, the rarity of their fall and the unexpected and. often 

 spectacular phenomena attending it; further, the specimens of 

 every fall have their own peculiarities, while they give the only 

 opportunity available for the actual contact-study of materials of 

 extra-terrestrial origin. The author is particularly fitted for the 

 preparation of a general volume on this unique subject, since he 

 has contributed much himself to our general knowledge of mete- 

 orites, both as to a description of new occurrences and from a 

 more comprehensive standpoint. An exhaustive study of the 

 North American meteorites by him was noticed in a recent num- 

 ber of this Journal (February, 1916, p. 223). It is also interest- 

 ing to remark that the Field Museum at Chicago contains the 

 largest collection of meteorites in the world. This collection, 

 which is under the care of Dr. Farrington, was inaugurated in 

 1894, and in 1912 the private collection of Henry A. Ward, 

 which alone included upwards of six hundred falls, was added to 

 it. Although a volume of only 220 pages, the present work 

 covers well, and concisely, the entire subject, from the discus- 

 sion of the phenomena of fall and geographical distribution, to 

 that of the structure and composition of meteorites, their classifi- 

 cation and origin, as well as their relation to terrestrial rocks. 

 This volume will at once interest the intelligent amateur and be 

 of value also to the trained specialist. 



12. The Data of Geochemistry; by Frank Wiggles worth 

 Clarke. Third edition. Pp.821. Washington, 1916. Bulletin 

 616 of the U. S. Geological Survey. — All interested in the rela- 

 tions existing between chemistry and the problems of the earth's 

 substance, history, and structure are much indebted to Professor 

 Clarke for his work on Geochemistry, which has now reached a 

 third edition. It appeared first in 1908 (U. S. G. S., Bulletin 

 330) and again as a second edition in 1911 (Bulletin 491). The 

 many workers who have used the volume do not need to have its 

 general scope explained (see this Journal, vol. xxv, p. 458); it is 



