86 EXPERIMENT STATTOIST EECORD. 



Modern technical building and construction methods, H. Gamann (Kul- 

 turtechnische BauJcunde. Berlin, 1912, vol. 1, pp. XIV+356, figs. 224). — This is 

 the first volume of this work and contains 4 chapters. Chapter 1, materials 

 of construction, deals with the general testing and strength of the various 

 materials entering into the construction of bridges, buildings, roads, and other 

 structures. Chapter 2, mechanics of construction, deals with those theoretical 

 and empirical parts of the mechanics of engineering which are employed in the 

 design of structures to be built of the above materials. Chapter 3, road con- 

 struction, deals with the design and construction of roads and pavements, 

 and with the construction machinery used. Chapter 4, sewage disposal, deals 

 with the design and construction of municipal, residential, and village sewage 

 purification and disposal systems. 



A large amount of tabulated working data accompanies each chapter. 



The manufacture of manila rope, C. W. Hunt (8ci. Amer. Sup., 7) (1912), 

 No. 1930, pp. 40Jt-.'f07, figs. llf). — This article describes the manufacture of 

 manila rope and gives the results of extended experiments on its use for the 

 transmission of power and for hoisting. 



These indicate in general that the amount of work that this rope will do 

 depends not only on the quality of the fiber and the method of laying up the 

 rope, but also on the kind of weather in which the rope is used, the diameter 

 and material of blocks or sheaves over which it is run, and the stress put 

 upon it. The principal source of destructive wear arises from an excessive 

 load or from defective or unsuitable sheaves. Four-strand rope is said to be 

 more serviceable than three-strand, since it is stronger for the same diameter, 

 and wears more nearly round and smoother. 



The breaking strength of manila rope in pounds, based on tests, is given 

 as 7160 X (diameter, inches)^ and the weight per linear foot in pounds as 

 0.34 X (diameter, inches)^ It is noted that pound for pound manila rope is as 

 strong as steel. 



A comparison of leather belts and manila rope for transmitting power indi- 

 cates that the rope 1 in. in diameter is equal in driving power to a double 

 leather belt 2| in. wide. Curves and tables of test data are given showing 

 the safe working loads and horsepower of manila rope of various sizes. 



Some observations and experiments on the tractive power of horses 

 {Engin. and Contract., 39 (1918), No. S, pp. 208, 209).— The results of experi- 

 ments by L. E. Conrad, as given before the Kansas Engineering Society, on 

 the tractive power of horse teams on average country earth roads with grades 

 varying from 2 to 9 per cent, indicate that instead of the usually accepted 

 amount of 25 per cent of the weight of the team being equivalent to its tractive 

 power on the level a more nearly correct index is from 35 to 40 per cent of the 

 weight of the team. 



The gasoline eng-ine on the fann, X. W. Putnam (Neio York, 1913, pp. 

 XXXI+527, figs. 179).— Thin is a practical and comprehensive treatise on the 

 construction, repair, management, and use of the internal combustion engine 

 as applied to the farmer's work indoors and out and to farm machinery. It 

 considers household, shop, and field uses of the gasoline engine, and includes 

 chapters on engine installation, power transmission, and the best arrangement 

 of the power plant with reference to the work. Because of the simple, non- 

 technical exposition of mechanical principles it is adapted for the use of those 

 without previous mechanical knowledge of the operation and care of gasoline 

 engines, tractors, and auxiliary devices. 



Experiments in motor cultivation at Bourg-es, G. Coupan (Bui. Soc. Agr. 

 France, 1913, Feb. 1, pp. 101-108, figs. //). — Several steam and internal combus- 

 tion tractors and motor plows were sub,iected to a 3-day plowing test. The 



