196 AGRICULTURE. BOOK I. 



though this science, in the confined sense of the word, has not 

 hitherto been of much real benefit to husbandry. 



These three kingdoms may be considered in another point 

 of view, and that is in regard to mechanical powers. The 

 qualities and capacities of matter, by means of which mecha- 

 nical power is effected, are its gravity, cohesion, extension, and 

 motion. The various powers of mechanism may be reduced to 

 the lever, and inclined plane. Upon the principle of the 

 former the steelyard is constructed ; on the latter, the wedge, 

 screw, and cart-wheel. The application of these in hus- 

 bandry is as various' and extensive as the diverse forms of its 

 machinery and implements ; from the spade, which is simply a 

 lever, and the plough, which operates chiefly on the principle 

 of the wedge, to the thrashing or grinding machine, which adds 

 to their powers the principle of the screw and the agency of 

 motion, and the cart-wheel, which acts as an inclined plane ac- 

 cording to its diameter and breadth. 



The importance of husbandry in completing the usefulness 

 of a country residence must be sufficiently obvious. But the 

 neglect of this study by those who have assumed the profession 



for converting grain into malt, has not yet suggested some new means of facilitating 

 the vegetation and final growth of those seeds, the product of which has long been 

 emphatically denominated the pabulum vita. 



