RURAL ENGINEERING. 489 



influence the success of the gas tractor in the State are the character of the 

 farming, the size and topography of the farms, the climate, the prosperity of 

 the farmer, and the present extensive use of machinery. He is of the opinion 

 that out of 225,000 farms in Iowa 50,000 could use the tractor with economic 

 success. 



The tractor situation in Indiana, A. H. Gilbert {Amer. Thresherman, 17 

 (1915), No. 11, pp. 10, 11, fig. 1). — Of 3G replies received from tractor users in 

 the State, 30 reported the tractor to be a practical investment, 2 said that it 

 paid fairly well, and 3 reported a failure. The author maintains that while 

 the present situation does not prove conclusively that the tractor is a profitable 

 investment for every farm, it can be made a paying proposition in Indiana. 



Small tractor a benefit to Kansas threshermen, R. C. Nichol {Amer. Thresh- 

 erman, 17 (1915), No. 11, pp. 7It, 75, fig. ^).— The author is of the opinion that 

 threshermen will be benefited materially from the present interest in small 

 tractors due to the increased yields brought about by the use of mechanical 

 power. 



The Minnesota view of traction engines, J. L. Mowry {Amer. Thresherman, 

 17 (1915), No. 11, pp. 18, 19, fig. 1). — In reviewing the tractor situation in the 

 State, the author states that the traction engine has not been a paying in- 

 vestment in the past, and he ia of the opinion that a 240-acre farm is the 

 smallest that can profitably use a traction engine. 



The necessary and most appropriate machines for the tillage of different 

 classes of soil, A. R. Uranga (Bol. Estac. Agr. Expt. San Juan Bautista, Ta- 

 basco, No. 9, (1913), pp. 40, figs. 61). — This bulletin describes and illustrates a 

 number of the more common tillage tools and other agricultural implements. 



Note on machines for pseudocultivation, M. Ringelmann (Ann. Inst. Nat. 

 Agron., 2. ser., 13 (1914), ^o. 1, pp. 5-Sl, figs. 10). — The author reviews a num- 

 ber of dynamometer tests of scarifiers, weeders, cultivators, and disk pul- 

 verisers in soils of different density. 



The results show that these machines, which the author terms pseudocul- 

 tivators, require a tractive effort per unit section of moved earth which is 

 equal to, and in some cases greater than, the tractive effort required per unit 

 section of moved earth for a double bottom plow in the same soil. They also 

 show the influence of the density of the soil on the required tractive effort for 

 these machines. With a soil density of 1.99, the average traction in kilograms 

 per square decimeter was for the scarifiers 45.5, weeders 72, cultivators with 

 flexible teeth 25.8, and pulverizer 31.8. The corresponding values with a soil 

 density of 2.03 were 47.9, 74.1, 42.9, and 50.3. 



It is stated that when these machines are operated on a soil which does not 

 support vegetation these results should be multiplied by a coefficient varying 

 according to the nature and state of the soil from 0.7 to 0.8. 



"With reference to a proposal that the pseudocultivators be used several times 

 in place of one passage of the deeper tilling plow, it is concluded that it is more 

 practicable to use the plow. It is further concluded that on the same work 

 under the same conditions less energy is expended on machines with flexible 

 teeth or shovels than with rigid shovels. The tests also show that the flexible 

 shovels should be fixed in groups of three to five on independent frames and 

 not on one rigid frame. 



Construction of sanitary mangers in dairy barn at Troy, Pa. (Concrete- 

 Cement Age, 6 (1915), No. 2, pp. 104-106, figs. 8). —-This article illustrates and 

 describes the method of construction of a large L-shaped dairy barn, 70 by 102 

 ft. in plan, wherein sanitaiy mangers have been installed. 



The housing of the agricultural laborer, H. D. Searles-Wood (Jour. Roy. 

 Sanit. Inst., 36 (1915), No. J, pp. 29-37, figs. 2).— The author discusses various 



