OPERATIONS OF TILLAGE. 143 



be fixed either to the side of the beam, or to the top and 

 bottom, as delineated in figs. 30 and 31. 



The ploughman may also give greater breadth by press- 

 ing the stilts towards the right ; though it is a bad plan, 

 and requires too much exertion to be continued through- 

 out a day's work. 



On the subject of draught, it may be observed, that 

 when horses are properly harnessed to the plough, their 

 traces will be in a direct line, firom the point of draught 

 at the shoulder, to the point of the share, passing through 

 the regulating notch of the muzzle. It is proper, there- 

 fore, to ascertain the animal's height, in order that the 

 muzzle may be fixed accordingly ; but as his shoulder is 

 not so far from the ground when he is pulling, as when 

 he is in a state of rest, an allowance must be made for 

 the difference. Thus, if a line be drawn from A, at the 

 share of the plough, to B, fig. 32, and then a perpendicu- 

 Fig. 32. 



lar line from B to C, at the horse's shoulder, an angle 

 is formed ; then if another perpendicular line be formed 

 from A to a, and measured upon the same scale, it will 

 give the height of the beam from the ground, at the depth 

 to which it is to be ploughed. 



It follows, therefore, that the more the beam is raised 

 in height, the longer it must be made, and consequently 

 the traces of horses must be lengthened : this, however, 

 lessens their power ; for it is sufficiently well known, 

 without entering into any mathematical proof upon the 

 subject, that the further the animal is placed from his 

 work, the less effectual will be his exertions. The Rev- 

 erend Mr. Priest made this experiment, with a furrow 



