64 



MODERN HORSE MANAGEMENT 



[chap. 



that in the winter their horses tire sooner in the 

 forelegs, and that their withers and crests are 

 continually in trouble. 



250. We will consider the effect of the resist- 

 ance between the horse and the road as the 

 traces are lowered. If the traces are very low, 

 as in P. 32, Fig. 2, the resultant force is acting 

 upon the shoulder from a lower point than if 

 the traces were horizontal. Now, if the traces 

 were attached to the ground vertically under tlie 

 horse, and the weight was hung on the traces, 

 the resultant force would be vertically down- 

 wards, which would offer the maximum resist- 

 ance between the feet and the road. Therefore, 

 the lower the traces the greater the resistance. 

 If the horse wore almost frictionless shoes and 

 moved on an almost frictionless road, it is clear 

 that it would be necessary to attach traces low 

 in order to obtain sufficient resistance. But this 

 is not the case. A horse with ordinary shoes on, 

 or with spikes or calks on ice, offers great resist- 

 ance between himself and the road, so that we 

 only need to increase this very slightly with 

 heavy draughts, and not at all with light. For 

 this reason a draught horse, in mounting a steep 

 hill, is often backed by its driver to help it pull 

 the load up more easily. 



251. From the above facts we gather that for 

 draught horses harnessed to heavy loads the 

 traces should be attached to the vehicle about 

 six inches below the horizontal, but with horses 

 attached to light vehicles an almost horizontal 

 trace should be used. The traces should tend to 

 work the collar upwards rather than downwards 

 over the shoulder ; hence the importance of a 

 large throat to the collar. 



The above points were considered when the 

 horse was moving on a horizontal or nearly 

 horizontal plane. When he moves up a steep 

 hill the conditions are not the same, as we will 

 consider later. The only difficulty to overcome 

 In the attachment of the traces seems to be in 

 the case of heavy sleighs. For these vehicles I 

 recommend an attachment as in P. 32, Fig. 5, 

 which, although costing a little more, would 

 repay the cost in a few months. In Canada 

 most vehicles used for heavy merchandise have 

 the wheels removed in the winter, and sleighs 

 fitted on to the axles {see P. 23&), so in this case 

 the brackets for raising the height of the traces 

 could be bolted on temporarily by a simple 

 arrangement. I do not see why such sleighs 

 should not be built higher off the ground, as 

 the wheeled vehicles are, although the cost 

 would be more and the liability of upsetting 

 greater, but not so great with heavy draught. It 

 would make it easier for lifting coal-sacks and 

 transferring heavy goods to the warehouses and 

 platforms, which are mostly built to f^t the 

 wheeled vehicles. 



Supposing a horse is drawing a load up a 20 

 per cent, grade, i.e. one unit rise to every five 



units of horizontal distance, which is a steep hill. 

 To draw the load up, the horse requires in- 

 creased resistance between his feet and the road, 

 so that he will be considerably assisted by 

 having the traces attached lower down on the 

 vehicle. The steeper the hill the lower should 

 they be attached ; of course, the hill itself will 

 cause the traces to assume a lower position 

 behind the horse. This would be impracticable, 

 so we must consider a more reasonable way of 

 helping a horse draw a heavy load uphill. We 

 find that by lowering the traces on the vehicle 

 we increase the resistance of the horse, i.e. the 

 apparent weight of the horse on the road, so the 

 same assistance will be given the horse by in- 

 creasing the weight on the horse's back. This 

 can be done in two ways : (1) as stated above, 

 by placing the driver on the horse, which has a 

 marvellous effect upon a horse that has been 

 unable to move a load without this extra weight ; 

 (2) by placing the load forward on a two- 

 wheeled vehicle, so that some of its weight bears 

 on the shafts. 



252. This brings us to the second point in 

 draught: Where should the weight be carried 

 on a two-wheeled vehicle? The two-wheeled 

 vehicle is the ideal one for carrying heavy loads ; 

 firstly, because the load must necessarily be 

 nearer the horse, and, secondly, because the load 

 can be altered in position to assist the horse on 

 varying inclinations of the road. The hansom 

 cab driver will stand up and lean forward, when 

 going up a steep hill, to assist his horse. On a 

 slight incline this should not be done. P. 32, 

 Fig. 3, shows the load at the back when the 

 horse is going uphill. Let AC equal the force of 

 the load and ad the lifting effect of the load 

 upon the horse, which he has to overcome. 

 Then, by completing the parallelogram adbc, 

 BA is the resultant force which the horse has to 

 exert. The direction of this force is such that 

 it tends to raise the horse's fe«t from the ground, 

 and therefore diminish his power. This power 

 becomes less and less as we increase the load on 

 the back of the cart, until the horse is unable to 

 move at all, and, upon a further increase, the 

 horse is lifted off his legs. 



253. Now, supposing the weight is placed 

 forward, as in P. 32, Fig. 4, then a'd' is the 

 weight acting vertically downwards upon the 

 horse, a'c' equals force of load ; then b'a' equals 

 resultant force horse has to overcome, in the 

 direction shown. This force is acting in a direc- 

 tion that tends to force the horse's feet into the 

 ground. From this it is clear that, for uphill 

 draught, part of the weight of the load should 

 be brought on to the shafts, or else the man 

 should mount the horse ; though in this latter case 

 the total weight will be unnecessarily increased. 

 But it is better for the driver to do this than 

 to ride on the cart, unless he sits well in front. 

 The easiest solution of this problem is for the 



