486 



ENGINEERING ON THE FARM 



number of plows increases. This is accounted for by the 

 fact that the cleaning of a choked plow requires all the plows 

 to stop, and the number of cleanings increases with the 



After J. I. Case Threshing Machine Co. 



After J. I. Case 1 hresrr.ns 



Fig. 376. A gas tractor drawing a three-gang disk 



number of plows. Fields suitable for tractor plowing should 

 be long, regular, and free from obstructions through which 

 the plow cannot be drawn. 



Grain-seeding machines, harrows, disks, and rollers on 

 soils that do not pack under the weight of a small tractor 

 have been operated extensively by tractor power, the tools 

 being coupled together so as to dispense with the services of 

 one man in accomplishing a given amount of work. At the 

 present time the ordinary tractor is not generally considered 

 as suitable for the cultivation of growing crops. Motor- 

 driven cultivators, hoeing tools, and other implements for 

 farm work have been placed on the market, but each has 

 its specially designed motor attached. 



During the World War the scarcity of help caused many 



