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THURSDAY, SEPTEMBER 30, 1915. 



ENGINEERING MATERIALS. 

 (i) Materials of Construction: Their Manufacture, 

 Properties, and Uses. By Prof. A. P. Mills. 

 " Pp. xxi + 682. (New York : J. Wiley and Sons, 

 Inc.; London: Chapman and Hall, Ltd., 1915.) 

 Price 195. net. 

 (2) The Strength of Materials: A Text-book for 

 Engineers and Architects. By E. S. Andrews. 

 Pp. X + 604. (London: Chapman and Hall, 

 Ltd., 1915.) Price 105. 6d. net. 

 (i) " A yrATERIALS. of Construction," by Mr. 

 iVl A. P. Mills, is an excellent text-book 

 covering- a wide field, including- cementing mate- 

 rials, masonry, bricks and clay products, ferrous 

 and non-ferrous metals and timber. Generally 

 a short historical statement is given, a list of 

 applications in the arts, a well-illustrated descrip- 

 tion of manufacturing processes, an account of 

 chemical, physical, and mechanical properties, and 

 some statistics of American production. The in- 

 formation is based largely, but not exclusively, 

 on American experience, but is not less interesting 

 on that account. English readers will be glad to 

 liecome acquainted with the very trustworthy 

 results of tests obtained by the U.S. Bureau of 

 Standards, the Structural- Materials Laboratory of 

 the U.S. Geological Survey, and the laboratory ^ 

 of the U.S. Forest Service, as well as the inves- 

 tigations of the active American Society for 

 Testing- Materials. 



The treatise is very comprehensive. For in- 

 stance, in treating- cements, there are separate 

 chapters on gypsum plasters, quicklime, hydrated 

 and hydraulic limes, Puzzolan and slag cements, 

 natural cements, Portland cement and concrete. 

 Or again, in dealing with ferrous metals, chapters 

 on pig- iron, cast iron, malleable cast iron, wrought 

 iron, steel, and the special alloy steels. There is 

 adequate criticism of the processes, the tests, and 

 the investigations described. 



Only a few points of interest can be referred to. 

 The researches of Le Chatelier, Tornebohm, and 

 the Newberrys on the constitution of Portland 

 cement are carefully summarised, and the chemical, 

 optical, and thermal researches at the Carnegie 

 Geophysical Laboratory at Washington, which 

 on the whole confirm the results of Le Chatelier. 

 Standard American tests for cement are given 

 and the conditions influencing^ the results are dis- 

 cussed. Curiously, rather little Is said of methods 

 of testing. The diagrams of tensile strength of 

 1:2, I : 3, and i :^ cement mortars with sand 

 graded to different fineness are instructive, and a 

 •constant relation of density and strength was ob- 

 served. Diagrams of the ratio of compressive to 



NO. •t2396, VOL. g6] • 



tensile strength, based on an extensive series of 

 tests of neat cement and cement mortars made 

 for the U.S. Geological Survey, are interesting. 



It appears that charcoal is used in the produc- 

 tion of about I per cent, of pig- iron in the United 

 States. A brief account is given of electric 

 furnaces, the product of which is claimed to equal 

 in quality Swedish charcoal iron. It is stated 

 that the electric furnace used for steel-making has 

 already become a formidable rival of the crucible 

 process, because it is able to make larger tonnages 

 of tool steel of crucible quality at lower cost. It 

 has also advantages in the production of alloy 

 steels in that it need not be operated under oxy- 

 dising conditions. 



The mechanical properties of materials are 

 shown by numerous graphic diagrams, which cor^- 

 dense in small space a large mass of results. It 

 is interesting that the U.S. standard specifications 

 for iron and steel express the elongation per cent, 

 in the form constant /(ultimate tensile strength). 

 This is the adoption of the Tetmajer coeflficient of 

 quality in commercial testing. The deviation of 

 this rule from the results of. tests, which is not 

 inconsiderable, is shown in Fig. 263^ Prof. Hatt's 

 results on the ratio of elongation and work of 

 rupture in static and dynamic tests will be new to 

 most EngUsh engineers. The treatment of fatigue 

 is imperfect. • • • 



(2) " Strength of Materials " is properly under- 

 stood to relate to the methods and results of the 

 experimental investigation of the physical con- 

 stants of materials of construction and the testing 

 of the quality of supplies from different sources. 

 It touches, on one side, the mathematical theory 

 of elasticity, and on the other, applications in the 

 theories of machines and structures. In the 

 volume by Mr. Andrews all these branches of 

 applied mechanics are treated together, and 

 strength of materials in the restricted sense is 

 rather perfunctorily dealt with. Riveted joints, 

 beams, struts, shafts, flat plates, and rotating- 

 discs are discussed mainly from a purely mathe- 

 matical point of view, graphic methods being 

 largely employed. 



No doubt the book will be useful to students 

 and young engineers, especially because 'so many 

 special cases are worked out algebraically and 

 numerically in detail. * At the same time it is 

 doubtful if the author has quite digested his 

 reading. On some fundamental points he is ob- 

 scure. Discrepant solutions are placed side by 

 side, and the student left to his own resources or 

 put off with "we believe." Thus two "theories arc 

 given of the simple case of a rectangular reinforced 

 beam. In a numerical example the bending 

 moment comes out three times as great by one as 



