February 27, 1885. 



SCIENCE. 



179 



the bitter injustice of the English writer and 

 the calm impersonality of the American opti- 

 cian, who was in the right, is skilfully woven 

 into a tribute to Tolles's character. There 

 follows a short appreciative memoir of Mr. 

 Tolles b}* Dr. George E. Blackham. 



The remainder of the volume is occupied by 

 the papers and proceedings, and contains ex- 

 ceedingly little original matter. There are 

 articles which repeat in detail perfectly familiar 

 modes of work, and others which deal with 

 those vague and worthless generalities of com- 

 monplace which characterize half knowledge. 

 Of the latter, the essay by Dr. J. Redding is a 

 too perfect example. It is on the extra- vas- 

 cular circulation, and is largely formed of com- 

 monplaces, the rest being half truths and total 

 errors. For example : Dr. Redding says (pp. 

 85, 86), " Bile, gastric juice, in fact all of the 

 so-called secretions, together with the worn-out 

 and effete tissue-detritus, are the result of 

 plrysical disintegration of the outermost sub- 

 stance of the cells." What can one do to 

 help the author ? Perhaps print the whole sen- 

 tence in italics, to point out the parts of it 

 which are erroneous. We find, however, 

 several articles of real interest. Some new 

 appliances for convenient work are described. 

 Gundlach's suggestion of a new method of 

 construction for objectives of low power, with 

 increased angular aperture, by changing the 

 crown glass of an achromatic lens, and adapt- 

 ing the flint glass to it, is noteworthy, and may 

 lead to a valuable improvement. Attention 

 should also be called to the very deserved 

 criticism, by Edward Bausch, of the English 

 1 society screw,' which is every thing save a 

 good standard. It is much to be regretted 

 that the volume contains so very little of results 

 of original research. 



THURSTON'S METALLIC ALLOYS. 



In this volume are brought together the re- 

 sults of the author's work 1 on metallic alloys, 

 with an introductory chapter on the history 

 and characteristics of metals and their alloys, 

 which is in the main the same as that to part 

 ii., and two chapters, one containing an enu- 

 meration of the uses of the non-ferrous metals, 

 and a statement of the location and reduction 

 of their various ores 



The materials of engineering. Part iii. Non-ferrous metals 

 and alloys. By Prof. R. H. Thurston. New York, Wiley, 1884. 

 144-575 p., illuetr. 8°. 



1 Reports of U. S. board to test iron and steel, etc., vol. i. 

 1878, and vol. ii. 1881. 



ing descriptions of the newer methods of work- 

 ing hot and cold metals. 



The scientific value of the experiments, 

 whose record and discussion constitute the 

 principal features of the book, and which were 

 confined to the mechanical properties of com- 

 mercial copper, tin, zinc, and their alloys, — 

 attention being chiefly given to the strength and 

 elasticity of these alloys when subjected to ten- 

 sile, compressive, bending, and twisting forces, 

 — is diminished by the failure to exercise due 

 care in the preparation of the alloys. The 

 need of great care in this matter is recognized 

 and emphasized by investigators, for most 

 alky's exhibit phenomena of liquation ; that is, 

 they tend, when melted and about to solidify, 

 to separate into their constituent metals, or 

 into several masses composed of different al- 

 loys. Special precautions with respect to 

 purit}^ of the metals, rate of cooling, oxida- 

 tion, temperature during melting, frequency 

 of agitation, etc., must therefore be taken, if 

 the resultant solidified mass is to be homoge- 

 neous. 



Professor Thurston is fully aware of this 

 liability to liquation; but on "assuming 

 charge of a series of experiments on the char- 

 acteristics of alloys, and an investigation of 

 the laws of combination," the duty assigned 

 him by the U. S. board, we find him holding 

 the following view of the work : — 



" The intention in the work here to be de- 

 scribed was, not to determine the character 

 of chemically pure metals, melted, cast, and 

 cooled with special precaution, but to ascer- 

 tain the practical value of commercial metals, 

 as found in the markets of the United States, 

 melted in the way that such ahVys are pre- 

 pared in eveiy foundry for business purposes, 

 and cast and otherwise treated in every respect 

 as the brass-founder usually handles his work ; 

 and to determine what is the practical value 

 to the brass-founder and to the constructor of 

 commercial metals, treated in the ordinary 

 manner, and without any special precaution 

 or any peculiar treatment." 



The book will be acceptable to the engineer- 

 ing public ; for, besides the author's own 

 work, it contains the views and results of other 

 investigators, extensive tables on the physical 

 and mechanical properties of bronzes and 

 brasses, and Bolley's compilation of the tech- 

 nically useful alloys, the author increasing this 

 rich collection still further by recipes from 

 French and American sources. The deter- 

 mination and topographical representation of 

 ' the strongest of the bronzes ' will also be 

 found of decided interest. 



