520 ON DRAUGHT. 



by attaching the traces to one of these steel-yards, the number of pounds indi- 

 cated on the dial will be the exact measure of the strain the horse exerts, and 

 the amount of strain is called his ' force of traction.' 



Having fixed as nearly as possible the meaning of these terms, which will 

 frequently occur in the course of our progress, we shall proceed to the division 

 of the subject. 



It is evident that there are three distinct agents and points of consideration 

 in the operation of draught, which are quite independent of each other. They 

 are First, the moving power and the mode of applying it; Secondly, the 

 vehicle for conveying the weight to be moved ; Thirdly, the canal, road, or rail- 

 way, or what may be generally termed the channel of conveyance. 



All these individually influence the amount of draught, and require separate 

 consideration ; but the mode of combining these different agents has also a 

 material effect upon the result, consequently, they must be considered in rela- 

 tion to each other ; and to obtain the maximum useful effect, with the greatest 

 economy, in the employment of any given power, it is evidently necessary that 

 these different agents should not only each be the best adapted to its purpose, 

 and perfect to the greatest possible degree, but also that they should all be com- 

 bined to the greatest advantage. 



We shall proceed, then, to examine the different agents now employed, the 

 modes of applying them, and the proportionate effects produced. 



And, first, with regard to the species of moving power ; this may be of 

 two kinds, animal and mechanical. 



By 'animal power' we mean the direct application of the strength of any 

 animal to dragging or pulling, as in the simple case of a horse dragging a cart. 

 By 'mechanical, 1 the application of any power through the intervention of 

 machinery : the source of power in this latter case may still, however, be 

 animal power, or a purely mechanical agent, as a steam-engine. 



The latter is the only species of mechanical power which it has been attempted, 

 with any prospect of success, to apply practically to locomotion ; and therefore 

 that alone we propose to compare with the animal power. 



Now, although these two powers, viz., simple animal power and the steam- 

 engine, may in most instances be applied so as to produce the same effect, and 

 may therefore, to a superficial observer, appear similar ; yet there do exist such 

 essential differences in the mode of action, or the means by which the effect is 

 produced, that there are many cases in which the one may be used, wherein the 

 other may be totally inapplicable. 



In this treatise, draught by animal power is the principal object of con- 

 sideration ; but as great efforts have been made for many years, and are still now 

 perseveriugly made, to supersede animal power entirely by mechanical, to 

 dismiss our old servant the horse, and supply his place by the steam-engine, 

 it may be as well, in justice to the former, to say a few words in his defence, 

 and to take a brief view of the distinguishing features of the two agents. 



To enter into all their respective merits, and to weigh their comparative 

 advantages in all circumstances, would involve us in many questions foreign 

 to that under our immediate consideration, and would embrace subjects 

 which may supply matter well worthy of our future attention. It is sufficient 

 for our present purpose to show that there still exist great objections to the 

 universal application of machinery to draught, objections which do not 

 equally apply to the use of animal power ; that there are many advantages in 

 the latter, which are not yet obtained by the former ; and that animal power 

 continues, for all the ordinary purposes of traffic upon common roads, to be the 

 most simple in its application, and certain in its effect. 



We shall confine ourselves particularly to the consideration of that part of 



