ON DRAUGHT. 



The investigation of the subject of draught by animal power, to which this 

 treatise is devoted, and which will form an appropriate supplement to an 

 account of the Horse,— has long and frequently occupied the attention of 

 theoretical and practical men ; so much so, that our object will be to 

 collect what has been said and done, and, by arranging it methodically, to 

 show in what manner the information may be applied and rendered useful, 

 rather than to attempt to produce anything absolutely new upon the sub- 

 ject. Notwithstanding, however, all that has been written, if we open any 

 of the authors who have treated the subject, in the hopes of obtaining 

 direct practical information, we shall be much disappointed. 



It might have been expected that the particular result of every method 

 known and in use for the conveyance of a load from one spot to another, 

 by animal power, whether by sledges, by wheel-carriages, or by water, as 

 in canals, being so constantly and necessarily a matter of practical expe- 

 riment, would have been accurately known and recorded ; — but the con- 

 trary is too much the case. 



The theoretical investigations have been made with too little reference 

 to what really takes place in practice ; and the practical portion of the sub- 

 ject has not generally been treated in that useful and comprehensive man- 

 ner which it deserves and demands. 



In fact, there is hardly a question in practical mechanics on which, 

 though much has been written, opinions are apparently less fixed ; or on 

 which the information we do possess is in a less defined and available 

 state. 



One great object of research has been the average force of traction or 

 power of a horse. 



If we consult the most approved authors and experimentalists, Desa- 

 guilliers, Smeaton, &c., we find this power variously staled as equal to 

 801bs., lOOlbs, 1501bs., and even SOOlbs : we are therefore left almost as 

 ignorant as before ; but the knowledge of this average power is fortunately 

 of little or no use in practice. It is the application and effect of that power 

 which alone is useful ; and that is governed by circumstances always vary- 

 ing and dissimilar, such as the form and state of the road, the structure of 

 the carriage, the size and friction of the wheels, &c. &c. ; and scarcely any 

 two cases of draught would, as regards the effect of the power of the horse, 

 present precisely the same result. 



The difference of opinion here manifest is still more remarkable when 

 existing on a purely practical question. 



In the inquiries instituted by a committee of the House of Commons in 

 1806 and 1808, on the subject of roads and carriages, two well-informed 

 practical men, Mr. Russel, of Exeter, and Mr. Deacon, of Islington, the 

 most extensive carriers in England, were examined upon an important 

 question, viz., the advantage or disadvantage of a particular form of wheel. 

 It was stated by one that, having given the wheels in question a twelve- 

 month's trial, he found that they tended to injure the road and increase 



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