EUKAL ENGINEERIISrG. 689 



Dynamite on the farm (Ayr. Jour. Union So. Africa, 3 {1912). No. 6, pp. 

 X02-80G). — This article notes the results obtained by subsoilinLr with gelignite, 

 a high velocity explosive, and with specially prepared agricultural dynamite, 

 a low velocity explosive. In using the gelignite the charges were sunk from 

 3i to 51 ft., the best results being obtained from the shallower charges. The 

 dynamite gave much better results than gelignite, since, as a low velocity ex- 

 plosive, it pulverized the subsoil over a much larger area. The facts as noted 

 indicate that for success and safety the work must be carefully and properly 

 handled. " Rules of thumb " must be avoided and nothing but the correct 

 implements and explosive to satisfy local conditions must be used. 



Study of agricultural machinery, M. Estrada (Bol. Min. Agr. [Buenos 

 .4ires], l) {1912), No. .), pp. S.H-J '/'/). — A discussion of experimental work on 

 agricultural machinei*y in Argentina and the United States and of agricultural 

 engineering education in the Unitetl States, dealing especially with motor ma- 

 chinerj% rural architecture, sanitation, irrigation, and drainage. 



How the plow hitch afEects draft (Threshermen's Rev., 21 (1912), No. 3, 

 pp. 9, 4Jf, JiG, -}S, figs. 3). — A graphical and mathematical analysis of draft and 

 a few suggestions pertaining to the hitching of engine gang plows are given. 



The conclusions are drawn that the best results are obtaine^l by making the 

 hitch a little to the right of the center of the plow and by hitching as high 

 on the engine as possible without carrying the front end of the plow off the 

 ground, and that the larger the plow the more economical it is iu power. From 

 the gi-aphlcal analysis the formula is deduced for the desired hitch for any 



1 c 

 sized plow of D= c.f,\„ , in which D = the distance in inches from the first 



plow center to the hitch, A = distance from the center of the first plow to the 

 tenter of the last plow, measured at right angles to the furrow, B = the dis- 

 tance from the center of the first plow to the center of the last plow, measured 

 parallel to the furrow, and G = the distance in inches from the front plow 

 bottom to the engine draw bar. For practical conditions 12 in. should be added 

 to D. 



Fifth Winnipeg motor contest, P. S. Rose (Amer. Thresherman, 15 (1912), 

 No. 5, pp. 3-11, figs. 18). — This contest was primarily one of fuel economy, 

 being divided into 3 main divisions: (1) a 2-hour economy brake test during 

 which the engines were supposed to run under their most economical load and 

 have determinations made of the fuel required per horsepower hour; (2) a 

 i-hour maximum brake trial under maximum load, with a fuel and water con- 

 sumption determination; and (3) a plowing test in which each tractor was 

 given a certain amount of land to plow and accurate records were kept of fuel 

 consumption. 



The tractive efficiencies as determined were veiy high, due to the good 

 ground condition, the gas tractors giving efliciencies from 59 to 8S per cent. 

 The steam engines showed considerably lower efliciencies. The results and 

 accompanying data indicate a 25 per cent increase in average economy since 

 1910, due principally to advancement in the art of engine building, which is 

 sufficient also to counteract the advance in price of gasoline. 



The status of the motor plow question in Germany, Martiny (Kiihn Arch., 

 2 {1912), pt. 1, pp. 193-229, figs. 12). — A general discussion of the theory of 

 operation of the motor plow, presenting graphical and mathematical explana- 

 tions of the losses by sinking and slipping of drive wheels in different types, 

 the action of plowshares in different hitches, etc., followed by the results of 

 practical experiments and by discussions of the efficiency, practicability, and 

 flexibility of various types. 



