ON DRAUGHT. 



The investiagation 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 any thing absolutely new upon the subject. 

 Notwithstanding, however, all that has been written, if we open any of the 

 authors wlio 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 methoa 

 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, a? 

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

 ment, would have been accurately known and recorded; but the contrary 

 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 subject 

 has not generally been treated in that useful and comprehensive manner 

 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, and others, v/e find this power variously stated as equal 

 to 80 lbs., 100 lbs., 1.50 lbs., and even 200 lbs: we are therefore left almost 

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

 tunately 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 varying 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. 



Tiie diflerence 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 importani 

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

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

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



