ON DRAUGHT. 539 



same horse working tlie same number of liours unloaded ; and that i lie 

 force of traction corresponding to this speed is equal to half the limit of 

 bis power. For instance, if six hours be the length of a day's work decided 

 upon and if a horse working that time can go six miles per hour unloaded, 

 and therefore producing no useful effect, and supposing the limit of power 

 of the same horse be equal to 250 lbs., it is found that he will do the most 

 work in the same number of hours when drawing a load at the rate ot 

 half six, or three miles per hour ; and half of 250, or 125 lbs., waU be the 

 strain corresponding to this speed. Our next step, then, niust be to find 

 these liimts: now, the hmit of velocity depends upon the length of time 

 durino- which the speed is kept up ; we subjoin therefore a Table deduced 

 from experiments, and which represents the proportion of the duration ot 

 labour and maximum velocity of the average of horses accustomed to their 

 respective velocities. 



Hours. , 



Duration of labour .. 1 2 3 4 5 6 7 8 10 



Maximum Telocity unloaded, in ? ^^3 ^gi 8^ 7^ 6| 6 5.^- 5:^ 42 

 miles, per hour . . ) * ''^ ^ 



This within the range here given may be considered as very nearly the 

 law of decrease of speed by increased duration of labour; and at the farst 

 o-lance we see the great advantage of reducing the speed and prolonging 

 the exertion There are, however, many causes to hmit the dui-ation ot a 

 day's work of a horse. Tredgold, in his work on Railways, before quoted, 

 says • ' The time assigned for the day's work of a horse is usually eight 

 hours • but it is certain, from experience, that some advantage is gained 

 by shortening the hours of labour ; and we have observed that a horse is 

 least iniui-ed by his labour where his day's work is performed m about six 

 houi-s • wher^ the same quantity of labour is performed m less than six 

 hours 'the over-exertion in time shows itself in stiffened jomts, while the 

 wear^no- effects of long-continued action become apparent, if the dui-ation 

 of the day's work be prolonged much beyond eight hours. Indeed, under 

 the management of a good driver, a full day's work may be completed m 

 the time before mentioned — six hours— with beneht to the health and 

 vigour of the animal' • ,i 



We may be permitted, however, to abandon the idea of improvmg the 

 health of the animal, or of rendering his business a pleasure to him— an 

 attempt the success of which is, we should think, very questionable, and 

 content ourselves with endeavouring to check the barbarous practice ot 

 working horses to death either by overdriving or overloading them; and 

 we shall, as is generally the case, consult oui- own interests, andfoUowthe 

 dictates of humanity at the same time, by not injuring so useful an animal : 

 and we think experience proves there will be no danger of doing this by 

 workino- eight or nine hours a day. By referring to the foregomg Table, 

 we see that the maximum velocity of the average of horses corresponding 

 to eio-ht hour's work is five miles and a half per hour, consequently, the 

 rate at which he would travel when loaded is a little more than two miles 

 and a half per hour. There is no doubt that some horses could con- 

 veniently travel faster ; but as the speed must generaUy be governed by 

 that of other horses, the average is, in this case, the rate to be adopted. 

 The force exerted under these circumstances depending upon the quality 

 of the horse, it is very difacult to obtain even an approximate value of it, 

 unless the experiment be made upon each individual horse : it is fortu- 

 nately, however, of no great consequence in practice, because if we feel sure 

 that Ave are employing all the foiver we can command to the greatest 

 advantage, it is not of uny very great importance that we should know 

 the exact amoiont of that power. 



