O.i AijricuUural Mechcv 



113 



when the aiigle is acute, than when it is obtuse. The reUitlve position 

 of the share and the coulter must then be such that they may cut a 

 square-cornered sod. With regard to their actual position in the plough, 

 it is obvious that the more inclined they are to their work, the more easily 

 will it be accomplished. The cut will be more gradual — less abrupt. 

 They should, therefore, be as much inclined to their work as is con- 

 sistent with a convenient form of the plough. 



■ ^' c/////y////d: 



Now it is evident that, though it may be necessary, when altering the 

 dimensions of your furrow-slice, making the plough go deeper or shal- 

 lower, or when going from one description of soil to another, as from a 

 clayey to a strong soil, to alter the position of the share or of the coulter ; 

 yet there can, under no circumstances, be any necessity for an alteration 

 in the /b7m of those parts of the plough. Here, then, is another part 

 of the plough which may be constant. We shall find that of all the parts 

 of the plough the mould-board alone will require to vary with the work 

 to be done. There should, howxver, be a means of altering the position 

 of the coulter; and this is one of the reasons of the failure of that which, 

 as I have said, has been tried instead of it. 



There are other means of regulating the position of the plough, 

 according to the nature of its work, which should, perhaps, have been 

 mentioned when the framework of the plough was described. It is 

 evident that the line drawn from the horses' shoulders, through the point 

 of attachment of the draught-chains to the plough, ought, if lengthened, 

 to pass through the centre of the resistance met with by the plough at 

 work. Should it be otherwise — should the line so lengthened strike the 

 mould-board at a point higher, for instance, than the centre of resistance, 

 then the effect of the draught will be to pull the plough over, and sink 

 the point of the share, till the implement, by increasing the depth of the 

 land ploughed, has raised the centre of resistance higher up the mould- 

 board. Should it strike the mould-board to the right or left of this 

 centre, then the plough in the same manner, in order that this centre 

 may be brought into the line of draught, will be forced to take a greater 

 or less width of land. This is the w ay in which the means act which 

 are adopted for altering the dimensions of the furrow-slice. 



VOL. III. I 



