PRINCIPLES OF DRAUGHT. 



121 



Whipple-trec for three horses. 



attached to the longer ends of the intermediate bars. 

 Fig. 96 represents the mode of attaching four horses in 

 draught, their force being equalized by passing the 



Fig. 96. 



Whipple-tree for four horses. 



chain round the wheel in the pulley-block, a, security 

 being provided that the hindmost pair shall not en- 

 croach on the forward pair, by connecting the end of 

 the chain at the same time to the plow. 

 F 



