196 



Report on Trials of Plows. 



whatever may be the amount of resistance at a, which has to be 

 overcome. 



The method of attaching three horses to the plow, most usual 

 in the State of New York, is shown in Fig. 104. In this case the 

 length of the whiffle trees is twenty-four inches; the secondary 

 evener is thirty inches, and the principal evener is forty-Hve 

 inches; in each case measuring between the draft-hooks. This 

 brhigs the horses very near together, but they cannot much 

 exceed this length if one of the horses walks in the furrow. In 



case the two horses are on the right hand and the one horse on 

 the left, the clasp-ring or hook which is attached to the plow 

 must be placed exactly at one-third of the distance between the 

 two hooks at each end of the principal evener, that is, fifteen 

 inches from the right hook; if the two horses are placed at the 

 left hand, then the distance must be reversed. In this case, as 

 before, each horse will pull exactly one-third of the load, for, as 

 the left-hand lever is just twice as long as the right-hand lever, 

 this last will take just twice as much power to draw it. If the 

 total draught of the plow is 600 pounds, the left horse will pull 

 one-third of it (200 pounds) and the two right-hand horses will 

 pull 400 pounds; the secondary evener being a lever having equal 

 arms, the load on each horse will be just half that amount — 200 

 pounds. If the nigh horse is heavier and stronger than the other 

 two, it will be still more convenient, as the long side of the evener 

 may then be somewhat shortened so as to enable the horse to 

 walk more easily in the furrow. 



When it is desired to attach four horses to the plow, it is 

 usually done by placing them two-and-two, one pair before the 

 other, the evener of the forward pair being connected with the 

 evener of the hinder pair by a long-chain called a soam-chain. 

 The horses next to the plow are connected l)y a neck-yoke, through 



