PROP ULSION IN DRA UGHT, 6 r 



2. The cart-horse ought to have a heavy neck as well as massive shoulders. 

 As a natural corollary to this proposition, which infers the lowering of the 

 head and neck, we must condemn the use of bearing reins with the class of 

 horse which we are now considering. 



3. The shoes of the horse should have toe-pieces when the ground is 

 favourable to their employment. 



On the other hand, when the horse, on account of the slippery nature of 

 the ground, is unable to use his fore legs, except to a very slight degree, as 

 propellers, the fore hand should be light and the head carried high. Thus, 

 the weight has to be kept almost entirely off the shafts of London hansom 

 cab-horses, which would be rendered very liable to fall down on the greasy 

 wood pavement and glass-like asphalt, if a fair proportion of the load were 

 to be put on their backs. Not alone is weight kept off their backs, but as a 

 rule it is so distributed as to cause the back-band to exert on the " girth- 

 place" an upward pressure, which, naturally, will more or less aid in "lighten- 

 ing" the fore hand. 



The force of propulsion given by the hind limb is dependent on a series of 

 levers which extends from the toe of the hind foot, along the bones of the 

 hind leg, pelvis, spinal column, up to the centre of pressure on the inner side 

 of the collar. It is manifest that the flatter this irregular line of levers is 

 with reference to the line of propulsion from the toe of the hind foot to the 

 collar, the greater will be the mechanical advantage at which the hind limb 

 will act. Consequently, we may infer that the cart-horse should be long 

 in the body, as compared to his height ; that he should be lower over the 

 croup than he is at the withers j and that he should not have a horizontal 

 croup. We should not, however, desire his hind-quarters to be so drooping 

 as to cause him to be actually " goose-rumped " (p. 208). 



The amount of forward propulsion given by the fore limb varies according 

 to the position of the humerus ; for the more horizontal is this bone, the 

 more effective will be the push. As its degree of slope with the ground is 

 directly affected by that of the shoulder-blade, it follows that the shoulders of 

 the cart-horse which has to fully exert the powers of his fore legs in propulsion, 

 should be more upright than sloping. 



It is a well-known mathematical fact that the most advantageous direction 

 for the pull in draught to be, is one which makes an angle with the ground 

 equal to the angle of friction, I may explain that if, for instance, 10° was the 

 greatest slope of ground upon which a body could rest without sliding down, 

 its angle of friction would be equal to 10". The best direction then of the 

 traces would be at an angle to the ground equal to the angle of friction. In 

 many cases the pull of the traces is not at a sufficient angle to the ground, 

 and the work is consequently performed at a mechanical disadvantage, which 

 might be remedied by the employment of a taller horse than the one used, 

 by having smaller wheels, or by a change in the harnessing arrangement. 

 For instance, in such a case, instead of attaching the traces to the hooks on 

 the shafts of a dog-cart, they might be connected, as is sometimes done, 

 to the axletree. 



