CAEE AND MANAGEMENT OF ANIMALS 829 



plenty of room, and three horses may be worked abreast 

 by means of a mechanical contrivance known as equalizing 

 whippletrees (Fig. 205). The mechanism is adjustable, so 

 that the horses may be placed closer together or wider 

 apart ; and it may also be arranged so as to save a weak 

 or young horse. 



Fif 



-Adjustable Whippletrees to enable three horses to work abreast 

 {Ransomes, Sims and Jefferies). 



An equalizing chain and pulley for a plough attachment 

 is shown at Fig. 206. The chain passes around a pulley 

 so that the animals pull against each other, and none can 

 escape their share of the work. 



Experiment shows that, generally speaking, a wide tyre 

 to a wheel renders traction lighter than a narrow tyre ; the 

 only advantage of a narrow over a broad tyre is on a very 

 dusty road. 



The height of a wheel has also an influence in traction ; 

 high wheels diminish draught, while a small wheel not only 



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1'-^ Pai/ of Horses 



S^ Pair of IIoi-€es 



Fig. 206. — Equalizing Chain and Pulley for four horses to insure each animal 

 takes its share of the work (Ransomes, Sims and Jefferies). 



increases it, but is more destructive to roads. It is an 

 advantage to have wheels which ' track,' viz., the fore 

 wheels the same distance apart as the hind, as the fore 

 wheels in heavy ground prepare the road for the hind, and 

 so reduce the force of traction. 



The weight in a four-wheeled waggon should be equally 

 distributed over the four wheels provided they are of the 

 same size, but if the front wheels be smaller than the hind, 

 then less weight should be placed upon them. 



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