BUBAL ENGINEERING. 591 



the gas tractor. It is the author's purpose to discuss the engineering features 

 of various constructiona only with a view of familiarizing the reader witli 

 the salient points of design so that the advantages of the various systems 

 of construction may be intelligently analyzed and the mechanism best adapted 

 to individual requirements be selected. 



The subject matter is presented under the following chapters: The scope, 

 advantages, and applications of power traction ; review of conditions on which 

 tractor design is based; design and construction of gas tractor power plants; 

 gas tractor power-plant components ; making and exploding the gas ; cooling: 

 and lubricating the power plant ; functions and construction of clutch, gear 

 set, and differential; the tractor frame, wheels, and axles; driviug and housing 

 the traction engine; traction-engine troubles and their elimination; and mis- 

 cellaneous rules and formulas. 



Plowing' by electricity in Italy, L. J. Keen a {Daily Cons. atUl Trade Rpt9^ 

 lU. S.], n (1914), No. 90, pp. S16, 317).— Data are quoted which show that 

 electrical power for plowing, when secured at 3, 4. and 5 cts. per kilowatt hour» 

 is considerably cheaper than steam or animal power. 



Electricity for country houses (Sci. Amcr. Sup., 17 (1914). Xo. 2000, pp. 

 287, 288). — The subject is discussed from the English standpoint, dealing par- 

 ticularly with the generator and accumulator aud quoting prices. 



Report of the departmental committee on the probable duration of builds 

 ings and other works for small holdings (London: Bd. Agr. and Fisheries^ 

 1912, pp. 21). — Numerous inspections made in England and Wales on buildings, 

 fences, and roads for small farms are reported. A large proportion of the 

 timber buildings and fences which have been in existence for from 20 to SO 

 years were found to be in good condition. The report favors the use of cor-, 

 rugated galvanized iron in tbe construction of farm buildings. 



The dwelling and the dampness of the dwelling, H. Steinberger (Die 

 Wohnung und die Wohnungsfeuchtigkeit. Berlin, 1914, pp. 116, figs. 17; rev^ 

 in Gsndhts. Ingen., 37 (1914), No. 12, p. 22.5).— This book, intended for tenants,, 

 house owners, architects, and engineers, treats of the sanitary aspects of house 

 location and construction, with particular reference to dampness in walls and 

 atmosphere, and the insanitary conditions resulting therefrom. Various 

 methods of preventing dampness and the growth of injurious fungi are con- 

 sidered, including a discussion on heating and ventilation. 



Homemade silos, H. Rabild, A. K. Risser. and K. E. Parks (U. 8. Dept. 

 Agr., Farmers' Bui. 589 (1914), PP- 47, figs. 37). — This discusses the general 

 considerations regarding silos, points out the es.sential features in their con- 

 struction, and gives detailed instructions for building the concrete, stave, and 

 the modified Wisconsin silo. The^ part relating to the stave silo is a revision 

 of a previous circular (E. S. R., 20, p. 6SS). It is pointed out that to make 

 the silo a profitable investment one should have at least ten cows or their 

 equivalent in other stock owing to the cost of the silo and the silo-filling ma- 

 chinery. 



The concrete silo is said to have the advantage of the other two types la 

 permanency and stability but is, as a rule, more expensive. The stave silo 

 is cheap and easily and quickly constructed, but it is a temporary structure 

 lasting only from 5 to 15 years, depending on the kind and quality of lumber- 

 used In its construction, and the climate. It is considered to be more liable 

 to blow down, fall down, or otherwise get out of repair than either of the other 

 types of silos. The modified Wisconsin silo is said to be more substantial than 

 the stave silo and is recommended for sections where it is inconvenient to 

 secure hoops or lugs for stave silos. The two objections to this type of silo 



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