OPERATIONS OF TILLAGE. 



145 



ness and evenness of the surface effected as far as prac- 

 ticable. 



In regard to the shape of the teeth, they should be 

 square, with a gradual taper to the point, the fore part 

 being kept straight, as in T, fig. 33. The teeth should 



Fig. 33. 



L iVI 



not be placed too closely together, for then they would be 

 too much impeded by the obstacles opposed to them : 

 they should be so disposed and drawn, that one tooth shall 

 not cut in the track of another, and that one part of 

 the instrument shall not be more interrupted than another : 

 their number should not be too great, because their pow- 

 er to penetrate into the ground will be diminished, unless 

 the weight of the harrow is considerably increased : and, 

 lastly, they should not be longer than necessary, because 

 an unnecessary length will expose them to greater ob- 

 structions, and render them more liable to split the frames 

 in which they are fixed. 



Harrowing is best performed when the land is dry, 

 13 XV. 



