texture, the tilling of land, and the acceleration 

 of chemical activities in the soil, are essentially 

 questions of physics; and these are the kinds 

 of scientific problems which the farmer needs 

 first to apprehend. 



15. Mechanics. In practice, mechanics is an 

 application of the laws of physics. ^ The ele- 

 mentary principles of mechanics are apprehended 

 by the farmer unconsciously, as a result of 

 experience ; but since modern agriculture is 

 impossible without numerous and often elaborate 

 mechanical devices, it follows that it is not 

 enough that the farmer be self-taught. At every 

 turn the farmer uses or applies physical forces, 

 in tools, vehicles, and machines. His work 

 often takes him into the field of civil en- 

 gineering. To show how much the farmer 

 is dependent on practical mechanics, we need 

 mention only implements of tillage, problems 

 associated with the draughts of horse tools, 

 the elaborate harvesting machinery, threshers 

 and feed- mills and milk- working machinery and 

 the power to run them, fruit evaporating ma- 

 chinery, pumps, windmills, hydraulic rams, con- 

 struction of water supplies, problems of animal 

 locomotion. 



16. Plant-knowledge, or botany. Since the 

 plant is the primary product of the farm, a 

 knowledge of its characteristics and kinds is of 



