100 SPECIAL SUBSOILERS. 



" Guibal found from experiments that the weight of the 

 machine should be 1,056 Ibs. to enable the teeth to penetrate 

 throughout their length in soils of medium stiffness ; he 

 advises weighting by cast-iron blocks, fixed between the spokes 

 by means of bolts, or to fix on the frame ^, wooden cases, which 

 may be loaded with earth (Fig. 64). The first of these two 



Fig. 64. Guibal's Subsoiler at work. 



means of increasing the weight should be preferred, for the 

 weight acts more directly on each tooth. The wheel revolves 

 round an axle a fixed on the wooden frame k made as narrow 

 as possible. On the rear of the frame a paddle board c is 

 fixed, so as to engage between each pair of teeth, forcing the 

 soil to fall back in the furrow directly it is raised. 



" Another paddle board/ is fixed to the front of the frame,, 

 and, engaging between the teeth, forces the soil to fall over 

 two iron plates fixed slantingly on each side of the frame. 

 By this means the soil is deposited on one side of the part 

 already ploughed, on the other on the part which is to be 

 ploughed; as a result the subsoil is disposed between two 

 layers of arable soil. According to the nature of the soil, 

 either of the paddle boards is used. 



" A lever fixed on the axle enables the machine to be kept 

 in equilibrium (Fig 65). 



" One or two poles for the yoking of horses or bullocks 

 completes the machine. 



u In course of work the wheel revolves, the teeth pene- 

 trating the soil ; the work cannot be better compared than 

 with that of a hand hoe. 



u As in the case of any other subsoiler, Guibal's machine 

 works in a furrow previously opened by an ordinary plough. 

 Two men and four horses are generally required. We see- 

 from this that its work costs double that of the plough. 

 Stones, roots of trees, <fcc., do not handicap the work of this- 

 subsoiler. 



