PT. I. 



OF TRANSPLANTING. 



11 



at the exact time and in the exact quantity that is 

 required^ and ceases of itself as the necessity for it 

 ceases. 



The principle of locking two-wheeled carriages 

 by creating friction on the wheels induces a shght 

 downward pressure on the horse's back. But the long 

 shafts act as a lever in the horse's favour, and the extra 

 pressure on his back is not to be spoken of in com- 

 parison with the labour of bearing back a loaded cart. 



That this is a fact any one may convince himselt 

 practically, by taking the water-cart which I have 

 described down a hill which is so steep that he could 

 not hold the cart back without this mode of blocking 

 the wheels. Might not this mode of blocking be 

 applied to two-wheeled carts ? 



