History of the Plow, 37 



or left. The right and left handles are furnished at A and D with 

 wooden helves, fitted into the sockets of the handles. If any one 

 Avill take the trouble to compare the means employed in Jethro 

 TulFs plow, Plate I, to make the plow run deeper or shallower, 

 more to land or from land, with the arrangements for this purpose 

 in the Rotherham plow. Fig. 16, they will see that a great 

 advance has been made, but an inspection of Small's bridle, as 

 shown in the plate, will demonstrate that much more convenience 

 and certainty has been attained by him in this respect, and nothing 

 since has been invented to accomplish this object which can be 

 pronounced materially superior to it. 



The general dimensions of this plow may be stated thus, as 

 measured on the base line: From the zero point, O, to the 

 extremity of the heel, T, the distance is four inches, and from O 

 forwards to the point of the share, R, the distance is thirty-two 

 inches — giving as the entire length of the sole, three feet. Again, 

 from O backward to the extremity of the handles. A', is six feet 

 two inches, and forward to the draught bolt, V, four feet seven 

 inches, making the entire length of the plow on the base line ten 

 feet nine inches; but, following the sinuosities of the beam and 

 handle, the entire length from A to C is about eleven feet three 

 inches. Although we have explained the word zero, used above, 

 in the chapter "On the Mechanical Conditions of the Plow," yet, 

 as it is a point of great importance in regulating the proportions 

 of the implement, and has received very little attention from 

 American plow makers, we here observe that the zero line is that 

 which, on the surface of the mould-board, where a vertical trans- 

 verse section at right angles to the plane of the land side falls, 

 which is distant from that plane by a space equal to the greatest 

 breadth of the furrow taken by the respective plows. The zero 

 point is found on this line, at an altitude above the sole the exact 

 height of the furrow slice. Or we may define it as that vertical 

 section of the mould-board which, in its progress under the slice, 

 will just touch the latter when in a vertical position. The scale 

 in this arrano-ement counts riiiht and left of zero. 



In reference to the body of the plow, the center of the coulter 

 box, K, is fourteen and a half inches, and the top of the breast 

 curve, M, nine inches before the zero point, both as measured on 

 the base line; but, following the rise of the beam, the distance 

 from M to the middle of the coulter box will be seven inches. 



The heights at the different points above the base line arc 



