682 SCIENCE PROGRESS 



shapeless flint chips (italics mine) discovered by Professor Commont. It is 

 clear that the author does not understand the nature of a flint-borer, which is 

 so called because it is fashioned by " reverse " flaking at its functional end. 

 The specimens described as " borers" are in reality "points." The flake 

 illustrated in Fig. 77 shows upon its bulbar surface what is certainly an 

 eraillure which is detached simultaneously with the flake itself. (This is, in 

 fact, made quite clear in the description of Fig. 75 bis, Plate XIII in 

 Mortillet's Musee Prehistorique, from which Fig. 77 is taken. Yet this 

 specimen is said to be an example with a chip crossing the bulb, as though to 

 reduce its inconvenient thickness, or to roughen the tool, and so to facilitate 

 grasping ! Finally, on p. 50, it is stated that " flint is very hard — harder than 

 steel." On p. 235 that early Chellean man " perforated flakes of flint," and on 

 p. 593 that the striae upon some Neolithic flints " might have been made 

 artificially, as ownership marks or, most probably, to roughen them, and so 

 facilitate firm grasping." Comment here is needless. 



The book is generously illustrated and can be recommended to archae- 

 ologists, so long as they remember that the\' must use their own judgment as 

 to the soundness of the opinions to which it gives expression. 



J. Reid Moir. 



A COLLECTION OF BOOKS FROM THE McGRAW-HILL 

 BOOK CO.. LONDON AND NEW YORK 



Electric Welding. By Ethan Viall, Editor American Machinist. [Pp. xii 

 + 417, with 329 figures.] (First Edition, 1921. Price 22s. net.) 



Gas Torch and Thermit Welding. By the same. [Pp. xi + 442, with 



85 figures.] (First Edition, 1921. Price 225. net.) 



Copper Refining. By Lawrence Addicks, Consulting Engineer. New 

 York City. [Pp. xii + 211, with 40 figures.] (First Edition, 192 1. 

 Price 17s. net.) 



Elements o£ Fuel Oil and Steam Engineering. By Robert Sibley, B.S,, 

 and C. H. Delany, B.S., M.M.E. [Pp xix + 466. with 248 figures.] 

 (Second Edition, 192 1. Price 28s. net.) 



Technical Methods of Analysis. Edited by Roger Castle Griffin, Director 

 of Analytical Department of the Laboratories of Arthur D. Little, 

 Cambridge, Mass. [Pp. xvi + 666, with 29 figures.] (International 

 Chemical Series. First Edition, 1921. Price 33s. net.) 



Gasoline Automobiles. By James A. Mover, Director of University Exten- 

 sion, Massachusetts Department of Education. [Pp. vii + 261, with 

 212 figures.] (First Edition, 192 1. Price lis. net.) 



The first five books in this list are of an extremely practical type, packed 

 with information of all kinds, both technical and commercial, which is likely 

 to be of use to persons actually engaged, or about to become engaged, in the 

 large-scale working of the various arts described. They are particularly 

 well illustrated with diagrams and photographs of plant, and are well indexed. 



The two books by Mr. Viall form a complete treatise covering every aspect 

 of welding ; either by oxy-hydrogen, oxy-acetylene, or by the latest process, 

 oxy-thermalene (thermalene is a gas obtained by the action of water on 

 calcium carbide in the presence of crude oil ; it is safer in use than acetylene, 

 and gives a slightly hotter flame — 6,500° F. as against 6,300° F.), by thermit, 

 by the carbon or metallic arc, or by the electrical resistance method. A 

 brief historical account of the development of each method is first given, and 

 then a description of the necessary lay-out, the procedure, and the class of 

 work for which the process is suitable. 



The book on Copper Refining is, apparently, a reprint of a series of 

 articles which originally appeared in Chemical and Metallurgical Engineering. 



