626 



FARMERS' REGISTER— ON DRAUGHT. 



forming a portion of the load to be moved, a cor- 

 responding poriion of the power is unprofitably 

 absorbed in moving it, and the excess, or remain- 

 ing power, is alone available for useful purposes,and 

 can alone be compared to the animal or horse pow- 

 er. Now, if the draught is augmented, as we have 

 just supposed, by any sand, dirt or roughness of the 

 road, or any other impediment, the force required 

 to move the useless weight (of the engine) is pro- 

 portionally increased; it may even, as we have 

 stated, be doubled or trebled; and the whole pow- 

 er of the engine remaining the same, the surplus 

 or remaining portion is considerably diminished, 

 and that at the very moment when, as before 

 stated, it produces only one-half or one-third the 

 efl'ect. 



Moreover, if at any part of the road a power 

 equal to twenty horses is required, the engine, as 

 regards its construction, must be a twenty horse 

 engine. It is erroneous to suppose that a steam- 

 engine, because it is a high-jiressure engine, can 

 therefore, as occasion requires, be worked for any 

 length of time beyond its nominal power, by mere- 

 ly raising the steam. Every part of a machine is 

 calculated and arranged for "ti certain pressure and 

 corresponding power, and that is a real [ower of it. 

 It is optional to work at or below that po\i-er, but, 

 if below, it will be to a disadvantage, and the bulk 

 and weight of the machine will be as great as if it 

 were always worked to its full extent, and both 

 have to be earned over all those parts of the road 

 where a far less power would be sufficient. The 

 velocity of the carriage might indeed be increased, 

 while travelling on the good and level portion of 

 the road, but these alternations in the speed and 

 power cannot be effected Avithout a considerable 

 degree of complexitj', weight, and expense in the 

 machinery, and as we are confining ourselves to 

 the consideration of the case where velocity is not 

 required, and might even be an inconvenience, the 

 excess of power will be vv^asted. 



These objections to the use of mechanical row- 

 er, in certain cases, are pointed out, not as being 

 insurmountable obstacles to the use of machinery, 

 but as serious difficulties which, in practice, have 

 not yet been overcome. In fact, there is not at pre- 

 sent any pra-ctical substitute for horse power on 

 common roads, and as far as the public is concern- 

 ed, nothing has yet been done. We, therefore, 

 must consider them as objections remaining to be 

 overcome; and we are compelled to draw the con- 

 clusion, that, at the present moment, animal power 

 (always confining ourselves to the question of the 

 economical transport of heavy goods upon com- 

 mon roads) is superior to any mechanical agent, 

 and that beasts of draught, and particularly the 

 horse, are not only the most anc'cnt but still re- 

 main the most advantageous source of power. 



Long experience has pointed out various modes 

 of applying animal power; but it is frequently ill 

 directed, owing to the want of an adequate know- 

 ledge of the mechanical structure of the animal, 

 and the manner in which he exerts his strength. 



In the most powerful sleam-engine, if too great 

 a resistance be applied, or, practically speaking, if 

 we attempt to make it do more work than it is cal- 

 culated for, there is an immediate loss of power, 

 in consequence of the diminution of velocity 

 caused thereby; and if we continue to oppose a 

 slill greater resistance, we reach the point at which 

 it is unable to overcome it, and it ceases to produce 



any eflect. Again, a very small obstacle may be 

 so applied as greatly to impede an engine of con- 

 siderable power, or even to stop it altogether. The 

 power of an engine is limited, and resistance must 

 always be proportioned to it; and there is a propor- 

 tion beyond which it is useless to go, and less than 

 which would not absorb the whole force. 



An animal is but a beautiful piece of machinery, 

 and although perfect in its construction, and won- 

 derfully acconuTiodating in its movements, it still, 

 like the engine, has a limited power, and has its 

 peculiar modes of action, its strong and its feeble 

 parts; and we must well consider its structure, to 

 be able to apply the resistance in that degree, and 

 in that manner which shall enable it to produce the 

 greatest efi'ect. The consideration of the compar- 

 ative effects of the exertions of a man and a horse 

 \\4ill at once exemplify this, and lead us more clear- 

 ly to the knowledge of the peculiar qualities or fia- 

 culties of the horse. ' 



If a horse be made to cany a heavy weight 

 rapidly up a steep ascent, or if a man be employ- 

 ed to drag slowly a heavy carriage along a rough 

 road, the strength of both will be soon exhausted, 

 and little eflect produced; but if a man be made to 

 carry a weight up a ladder, and if a horse draw a 

 heavy carriage along a road, they will each pro- 

 duce a considerable eflect: yet, in the former case, 

 the horse and the man are as strong as in the lat- 

 ter, but their power is not properly applied, and is 

 consequently wasted. 



These different resuhs are easily explained, by 

 considering the mechanical structure of the two 

 bodies, and the mode in which their muscular 

 strength is exerted. 



The action of pulling is effected in either cnse 

 by throwing the body forward beyond the feet, 

 which form the fulcrum, and allowing the weight 

 of the body, in its tendency to descend, to act 

 against the resistance ajiplied horizontally, and 

 drag it forward; as the resistance yields, the feet 

 are carried forward, and the action renewed, or 

 rather continued. 



We shall here consider both the quality of the 

 draught and the degree. 



And first, it is to be observed, that although the 

 weight of the animal's body is the immediate 

 cause in the action of pulling, yet, as before stated, 

 it is by the action of the muscles in advancing the 

 legs and raising the body, that this cause is con- 

 siantly renewed, and the efibrt continued. The 

 manner, and the order of succession in which a 

 horse thus lifts and advances his leps may, of 

 course, influer.ce the movement of his body, and 

 ought therefore to be examined into: accordingly 

 we find that many wiiters upon draught have 

 touched upon tliis part ol' the subject, but they ap- 

 pear to have contented themselves with inventing 

 in their closet the manner in which they conceived 

 a horse must have moved his legs, rather than 1o 

 have tuken the trouble to go out of doors to see 

 what really did take place, and, consequently, 

 many have arrived at erroneous conclusions. The 

 ancient sculptors, who generally studied nature so 

 faithfully, either neglected this point, or otherwise 

 our modern horses, by constant artificial training, 

 have altered their steji: for we find in the cele- 

 brated frieze, fiom the Parthenon at yVthens, a 

 portion of which, now in England, is more com- 

 monly known under the name of the Elgin mar- 



