OPERATIONS OF TILLAGE. 139 



but it is frequently expedient, on account of the irregular- 

 ities of the surface or other causes, to change the direc- 

 tion of the ridges at some part of the field, so as to 

 facilitate the discharge of the water. 



'' The application to this case of the principle of stri- 

 king the furrow is easy. The ploughman makes a furrow 

 where the change of direction is to take place, straight or 

 curved, as circumstances may require. The one set of 

 ridges terminate at this part, and the others are laid off 

 from it in the new direction to be given. The plough- 

 man, by means of his poles, as before, strikes his first set 

 of furrows, terminating them at the furrow where the 

 change of direction is to take place. From this furrow 

 he strikes his second set of furrows in the direction in 

 which they are to run. The part where the opposite set of 

 furrows meet, may be made an open furrow, or a raised- 

 up ridge, or head-land, as circumstances may require. 



" The direction of the ridges must generally be regula- 

 ted by the sloping of the fields, and the lying of ditches 

 and fences, so that they may promote the main purpose 

 for which they are formed, the carrying off of surface- 

 water. But, other circumstances being alike, they should 

 be made to lie as much as possible north and south, and 

 as rarely as possible east and west ; for, in the latter case, 

 when the ridges are much elevated, the north side has a 

 somewhat less favorable exposure than the south side. 



'' Sometimes ridges are altogether dispensed with, 

 either where the land is very dry, or where it is wished to 

 keep it in grass, and give it the aspect of a park or lawn. 

 In this case, the ploughs may either follow each other round 

 the entire field, and terminate at the centre, or they may 

 plough in large divisions, as in the case of cross-ploughing. 



" In ploughing very steep land, it is frequently laid in 

 ridges diagonally across the slope, for the purpose of 

 rendering the labor more easy, and of lessening the dan- 

 ger of torrents carrying away the surface. 



" The precaution to be observed in this case is, to 

 make the ridges slope upwards from the right hand, as 

 from A to B, fig. 29, and not from the left hand, as 

 from C to D. For in the first case, when the laboring 



