484 EXPERIMENT STATION RECORD. [Vol.43 



are discussed showing the complexity of the problem, particularly when it is 

 desired to substitute intelligently mechanical power for horse power. 



The present position of mechanical road traction, C. G. Conkadi {Jour. 

 Inst. Mech. Engin. [London'], No. 9 {1919), II, pp. 661-701, pis. 8, figs. 24; also 

 in Engineering [London], 108 {1919), Nos. 2813, pp. 714-718; 2814, pp. 764-768, 

 figs. 53; abs. in Electrician [London], 83 {1919), No. 24, pp. 682-687, figs. 8; Sci. 

 Abs., Sect. B— Elect. Engin., 23 {1020), No. 267, pp. 121, i22).— Descriptions are 

 given of the different kinds of vehicles used in England for mechanical trans- 

 portation, together with considerable data on operating experience. 



It is concluded that animal traction and electric vehicles are the most ap- 

 plicable for frequent-stop delivery, steam for heavy hauls at moderate speeds 

 over comparatively long distances, gas motor vehicles for work involving few 

 stops and high speeds, and electric tractors for heavy haulage. Electric vehicles 

 were found to possess a maximum degree of reliability of 95 per cent, gas motor 

 vehicles 90 per cent, and steam 85 per cent. Spur gears, especially internal 

 gears, are recommended for reduction gearing. 



Tests of an electric vehicle running with the differential gear locked and free 

 are also reported. It was found that when the differential gear was locked the 

 power required was from 7 to 12 per cent higher, according to the load, and 

 the wear on the tires was greater. 



Farm tramways {Min. Agr. and Fisheries [London], Leaflet 341 {1920), pp. 

 4, figs. 3). — This leaflet briefly describes British practice in regard to farm 

 tramways, many of which are said to be laid down in parts of England where 

 the land is flat. 



Protection of the tractor against freezing, G. PASSELfecuE {Jour. Agr. 

 Prat., n. ser., 33 {1920), No. 4, pp. 72, 73, fig. 1). — An apparatus is described 

 which is to be attached to the radiator of a farm tractor as a protection 

 against freezing. The apparatus is so constructed that water from the radiator 

 obtains access to it, this water freezing before the water in the radiator as 

 the temperature decreases. The freezing of the water in the apparatus causes 

 the draining of the radiator of the tractor. 



Reclaiming swamp land with tractors, W. Ashby {Power Farming, 29 

 {1920), No. 5, pp. 9, 10, figs. 3). — A year's experience in the reclamation of a 

 ditch-drained swamp in St. Louis County, Minn., by tractors is recorded. 



Five tractors were used as follows: Two 45-h. p. tracklaying machines with 

 30-in. tracks, one 75-h. p. tracklaying machine with 24-in. tracks, one 20-h. p. 

 tracklaying machine with 6i-in. tracks, and one 22 h, p. wheel tractor. These 

 machines all did good work in breaking on hard ground, but in the softer parts 

 of the swamp the 45-h. p. machines with 30-in. tracks were the only ones 

 which could be depended upon. Tabular data show that the weight of the 

 45-h. p. tractors per square inch of ground contact was 3.17 lbs., while that of 

 the 75-h. p. machine was 5.48 lbs. and the 20-h. p. machine 3.85 lbs. The two 

 latter machines slid the tracks on soft ground. It is noted that the three 

 large tractors working an average of only a little more than two months apiece ■ 

 broke 1,350 acres of wild land, disked 1,200 acres, and completed the seed7' 

 bed preparation of 350 acres. 



Experiments on the mechanical cultivation of rice in Cochin China, , 

 M. Labaste, M. p. M. Legbas, and P. Morange {Bui. Agr. Inst. Sci. Saigon 

 [Cochin China], 1 {1919), No. 1, pp. 4-1^; f^^^- in Internatl. Inst. Agr. [Rome^, 

 Internatl. R&v. Sci. and Pract. Agr., 10 {1919), No. 4. pp. ^66-^68).— Cultivation, 

 experiments in rice fields and on red soils growing Hevea are reported, in] 

 which a 45-h. p. caterpillar tractor was Tised drawing two 4-furrow gang plows] 

 with wooden frames and a Norwegian harrow with a metal frame. 



