170 Reviews — Stratigraphy of North America. 



earth-pressure ; but Professor F. D. Adams (Journ. Geol., 1912, 

 pp. 97-118) has sliown experimentally that empty cavities may exist 

 in a rock like granite under pressure equivalent to depths of at least 

 11 miles, and that thev" may exist at still greater depths if filled with 

 liquids. Colonel Burrard's assumption, therefore, does not appear to 

 be impossible from this point of view. 



In 1904 the Rev. 0. Fisher' partially anticipated the results now 

 obtained by the Survey of India by calculating the deflections of the 

 plumb-line in North India which would follow from his theory of 

 mountain compensation by a ' root ' extending to a depth of about 

 29 miles. The variations now observed are, however, more violent 

 than those expected by Mr. Fisher, for the northerly deflections 

 of the plumb-line decrease to zero at a distance of about 15 instead of 

 over 60 miles from the visible foot of the hills. It will be interesting 

 now to obtain a comparison of the observed deflections with those 

 calculated by Mr. Fisher, whose theory, however, does not otherwise 

 march, like that now oflPered, in consonance with the growing belief 

 in a solid earth. Thomas H. Holland. 



II. — Index to thk SruATiGRAPHr of North Ameiiica. By Bailey 



Willis. Accompanied by a Geological Map of North America, 



dated 1911. 4to ; pp. 894, with 19 text - illustrations. 



Washington : United States Geological Survey, Professional 



Paper 71, 1912. 



rpmS elaborate volume, although designed to explain the geological 



I map which accompanies it, will be a permanent and invaluable 



work of reference on the North American formations. In turning 



over the pages we are reminded of a letter by Dr. F. A. Bather on 



" Stratigrapliical Names", printed in the Geological Magazine for 



March, 1912, p. 141. Therein he calls attention to the number of 



names for formations and periods, remarking that his card-index to 



them extends to a thickness of more than two yards; and he 



comments on the inconvenience of the application of the same 



topographic names to formations of different ages in various countries. 



In the present work we find a Hastings Series of Pre-Caiubrian age ; 



and such names as Lebanon Limestone, Athens Shale, and Canaan 



Dolomite applieil to Ordovician strata in America. In that country, 



where so many British and other European names have been given 



to towns and villages, it would be difficult to avoid the application 



of some of them to local sedimentary divisions; and we find among 



' Phil. Mag., January, 1904, p. 14. According to an anonymous review 

 recently published in Nature of February 27 (p. 704), Col. Burrard is said to 

 have overlooked this paper by Mr. Fisher. He, however, answered it in the 

 same volume of the Phil. Mag. (p. 292) ; but the Editor of Nature, although 

 he is aware that Col. Burrard is in India and cannot thus reply for some weeks, 

 has refused to correct his statement on the grounds that the remark " applies 

 with perfect correctness to the memoir reviewed". In other words, the 

 reviewer is able to distinguish between the knowledge possessed by Col. Burrard 

 and that possessed by the writer of Col. Burrard's memoir ! The existence of 

 this uncanny ability suggests a clue to the origin of the legend that the Editor 

 of Nature sometimes appears to confuse himself with the Author of it. 



