2 o 8 The Four-coulter d Plough. Chap . XIX P 



the Axis of the Beam let down to the Surface, and 

 the prick' d Line g f parallel to the left Side of the 

 Share; but this Angle will vary as thofe Two prick'd 

 Lines are produc'd forwards to the Fore-end of a 

 long and a fhort Beam, keeping the fame Subtenfe: 

 For Plough-wrights always take this Subtenfe at the 

 Fore-end of a Beam, whether it be a long Beam or 

 fhort one; and it is the Subtenfe eg, that determines 

 the Inclination the Point of the Share muft have to., 

 ward the left Hand. Plough-wrights differ much in 

 this Matter ; but, by what I can learn by thofe that 

 make the Ploughs I fee perform the beft, this Sub- 

 tenfe at the Fore-end of an Eight-feet Beam mould 

 never be more than one Inch and an half ; and by full 

 Experience I find, that whether the Beam be long or 

 fhort, the Subtenfe muft be the fame ; for when my 

 Plough-wrights take this Subtenfe at Eight Feet from 

 the Tail, when they make my Four-coulter Plough, 

 whofeBeam is Ten Feet Four Inches long, the Point 

 of the Share will incline too much to the Left, and 

 it will not go well until this Fault be mended, by 

 taking the fame Subtenfe quite at the End of the 

 Beam ; which makes the mentioned Angle more 

 acute. 



Fig. g. Shews the right-hand Side, and upper Side 

 of the Four-coulter Plough, of which V the Iron 

 Ground-wrift is (hewn in Fig. 9. long Two Feet Five 

 Inches, deep at the End b Four Inches, and Three- 

 eighths of an Inch thick, except at the End a, where 

 it is thin enough to bend, fo as to fit clofe to the 

 Share, as at e, in Fig. 6. The Ground-wrift has 

 Four fmall Holes near its End a^ into one of which 

 goes a Nail, to fallen it to the Sheat, thro' the long 

 Hole in the Side of the Socket of the Share, as at 

 a, in Fig. 10. and then it will ftand in the Pofture 

 (hewn by e /, in Fig. 6. From the Outfide of the 

 Ground-wrift at/, to the Outfide of the Share at b^ 

 is Eleven Inches and an half, which is the Width of 



the 



