Engineering Wonders of the World
Volume III

298 ENGINEERING WONDERS OF THE WORLD. A GREAT 25-FURROW GANG PLOUGH, PULLED BY A STEAM TRACTOR, AT WORK ON A BIG CALIFORNIAN RANCHE. we consume has never been touched by human hand until it comes from the oven as bread or pastry. To revert for a moment to the great steam tractors described above. These find em- ployment in operations other than reaping. The American farmer works Tractors for outfit for all it is worth. So, Ploughing. when the sowing season comes, he hitches to his tractor a twenty-five-share plough ; behind that in succession a number of harrows, a drill and seeder, and other harrows. In this way the land is ploughed, pulverised, and sown as fast as the machine can travel. We can hardly expect to see labour-saving developed further, so far as agricultural operations are concerned. The direct ploughing system, in which the engine travels ahead of the plough over the land to be cultivated, is not practicable in this country with very heavy locomotives, the cable system being found much more effec- tive. This does not signify, however, that direct cultivation by power is not practised, as in recent years the light pet- rol or paraffin internal cpmbus- ASricuItural tion tractor has obtained recog- nition among farmers for ploughing, reap- ing, threshing, chaff-cutting, etc. The weight of the agricultural motor being under two tons and distributed over broad wheels, the pres- sure per square inch on the ground at points of contact is actually less than that of a horse’s hoof. A two, three, or four-furrow plough, according to the nature of the soil, is hauled by the motor, which is able to turn in a small circle, and so is as handy on the headlands as a team of horses. One form of motor plough has a double set of shares, arranged on the same principle as the cable- hauled balance plough, so that the direction may be reversed without turning round the machine. This plough is furnished with a light anchored cable which may be hauled on