76 POWER AND THE PLOW 



the cylinder after the explosion; for transforming the movement 

 of the piston into rotary motion suitable for driving machines, 

 and for lubricating the engine to reduce friction. In other 

 words, we must have a cylinder, cylinder head, piston, fuel 

 supply, carbureter, governor, ignition system, valves, cooling 

 system, wristpin, connecting rod, crankshaft, flywheel, and 

 lubricating devices, with a base for the support of all these 

 parts. 



In the early nineties, or shortly after the gasoline engine 

 was first successfully used for stationary purposes, a tractor 

 equipped with such an engine for power was offered for sale. 

 This proved unsuitable in many respects, and, since at that 

 time there was much competition from steam threshing engines 

 and little demand for a plowing tractor, the venture did not 

 survive. At least ten years elapsed^ before foe gas tractor 

 proved at all successful commercially. The year 1903 really 

 marks the beginning of the great development of gas tractors, 

 which has been one of the marvels in the history of agriculture. 

 By the spring of 1908 the builders of the first successful tractor 

 had about 300 machines in the field, and the sales that year 

 equalled those of the five years preceding. The following year 

 the number hi the field was again doubled, and by the close 

 of the year 1910 over 2000 of these tractors were said to be in 

 active service. Another company began to produce a small 

 tractor in 1907 and by the close of the decade was selling several 

 thousand yearly. Dozens of gas tractor factories sprang up, 

 and practically every manufacturer of steam traction engines 

 either went out of business or added an internal-combustion 

 engine to his line. At present over sixty firms are offering gas 

 tractors to the public and the number is being added to almost 

 weekly. For plowing purposes there is little question that this 

 type of prime motor has taken a permanent lead over the steam 

 engine. On that account, and because of the comparative 

 newness of the field, the mechanical features of the gas tractor 

 will be dealt with in greater detail. 



