1916] RURAL ENGINEERING. 687 



cylinders, well foundations, standard caissons, open caissons, pneumatic cais- 

 sons, and the effects of compressed air. 



Tables giving data on loads on foundations, skin friction, properties of ma- 

 terials, pile-bearing formula, steel sheet piling, quantities and cost for the 

 pier of the American River bridge, decompression periods, and stage decom- 

 pression are appended. 



Economy in bridge design and construction, H. W. Joyce (Calcutta: Bengal 

 Secretariat Book Depot, 1915, pp. [IV]+9S, pi. 1, figs. 55). — This is a series of 

 six lectures on the subject delivered to the students of the Sil)pur Engineering 

 College. 



Value of the high-pressure steam test of Portland cements, R. J. Wig and 

 H. A. Davis {U. S. Dept. Com., Bur. Standards TechnoL Paper 47 (1915), pp. 

 3.'/, pis. 2, figs. 4; abs. in Sci. Abs., Sect. B— Elect. Engin., 19 (1916), No. 220, 

 p. 127). — Investigations made to establish "if possible, a relationship between 

 the behavior of Portland cements in high-pressure steam and their physical 

 properties under normal conditions of use and exposure and to determine what 

 value, if any, the high-pressure steam test has as a means of detecting un- 

 soundness which might cause a weakening or disintegration of the cement 

 or concrete " are reported. 



" The qualitative high-pressure steam test used consists of subjecting an 

 ordinary soundness pat, which has been stored for 24 hours in a damp closet, 

 to a steam pressure of 300 lbs. per square inch for at least one hour, the 

 total time in the high-pressure boiler being three hours. A cement was said 

 to pass this test when it exhibited no cracking, warping, or disintegration on 

 examination after the treatment. 



" The quantitative high-pressure steam test consists of molding six briquettes 

 of neat cement at normal consistency, storing these test pieces 24 hours in a 

 damp closet, then subjecting three of them to an atmosphere of steam at 300 

 lbs. pressure for at least one hour; the total time in the high-pressure boiler 

 being three hours. The briquettes (both treated and untreated) are then 

 broken in a shot-testing machine. A cement was said to pass this test when 

 the treated briquettes exhibited greater strength than the untreated ones." 



The following conclusions are drawn from the results obtained : 



" The high-pressure steam test should be made on all cements that are in- 

 corporated in cement, mortar, or concrete products that are to be cured in 

 steam at pressures above atmospheric. The high-pressure steam test may be 

 of value as forecasting the behavior of neat cement or a very rich mortar 

 when exposed under normal conditions in dry air, but it vpill not forecast the 

 behavior of cements in concretes as normally exposed. The cement passing 

 the high-pressure steam test is not superior in cementing quality, as determined 

 from the compressive strength of concretes, to cement that fails to pass this 

 test. The cement passing the high-pressure steam test does not make more 

 permanent or durable concrete than cement which meets the requirements of 

 the standard specification, but fails to pass this test. Cement failing to pass 

 the standard specification atmos-pheric steam test, but meeting the other re- 

 quirements of the standard specification shows in some instances a normal 

 strength in concrete. For practical work under normal conditions of construc- 

 tion the results of this investigation fail to show that the high-pressure steam 

 test is of value as a means of determining the ultimate soundness of concrete." 



Testing the belt power of a tractor, E. C. Gee (Pover Parining, 25 (1916), 

 No. 6, p. 9, figs. 2). — This is a brief illustrated description of the prony brake 

 test as applied to a tractor. 

 64968°— 16 7 



