96 



MECHANICS. 



CHAPTER V. 



APPLICATION OP MECHANICAL PRINCIPLES IN THE STRUC- 

 TURE OF THE PARTS OF IMPLEMENTS AND MACHINES. 



In contriving the more difficult and complex ma- 

 chines, the principles of mechanics must be closely 

 studied, to give every part just that degree of strength 

 required, and to render their operation as perfect as pos- 

 sible. But in making the more common and simple 

 implements of the farmer, mere guess-work too often 

 becomes the only guide. Yet it is highly useful to ap- 

 ply scientific knowledge even in the shaping of a hoe- 

 handle or a plow-beam. 



The simplest tool, if constantly used, should be form- 

 ed with a view to the best application of strength. 

 The laborer who makes with a common hoe two thou- 

 sand strokes an hour, should not wield a needless 

 ounce. If any part is heavier than necessary, even to 

 the amount of half an ounce only, he must repeatedly 

 and continually lift this half ounce, so that the whole 

 strength thus spent would be equal, in a day, to twelve 

 hundred and fifty pounds, which ought to be exerted 

 in stirring the soil and destroying weeds. Or, take 

 another instance : A farm wagon usually weighs near- 

 ly half a ton ; many might be reduced fifty pounds 

 in weight by proportioning every part exactly to the 

 strength required. How much, then, should we gain 

 here? Every farmer who drives a wagon with its 



