LOCOMOTOR SYSTEM 647 



in a steady pull is known as the limit of his strength ; no horse can 

 possibly exert in draught a force equal to that of his own body 

 weight. The writer tested the question on the dynamometer, and 

 found that horses pulled, according to their spirit, from 65 to 78 per 

 cent, of the body-weight.* The grouping obtained was as follows : 



Excellent pullers, 78*5 per cent, of their body weight. 

 Good „ 77* 6 „ „ „ 



Fair „ 70-6 



Bad „ 65-6 



The only horse he met with which pulled 88 per cent, of his own 

 body weight was the animal mentioned above as moving thirteen 

 men. 



The Weight a Horse should Draw is a question frequently asked. 

 Other things being equal, an animal's power of traction varies 

 directly as his body weight. Working on these lines, an attempt 

 has been made by the writer to ascertain, in the regular draught- 

 work performed generally throughout the country, what proportion 

 the total load bears to the horse's body weight. In this way it is 

 hoped data have been obtained which will enable the question of 

 overloading to be dealt with on a sound basis. 



The mean of 650 observations in England was that the horse 

 dragged a load equivalent to 253 times his body weight. From 

 the nature of the inquiry it was impossible to avoid favourable cases 

 being selected, but subsequent investigations, where this was speci- 

 ally avoided, show that for work outside towns and cities this ratio 

 may be accepted. f In cities, where the roads are good and friction 

 reduced to a minimum, the ratio of load to body weight may be 

 raised to 1 to 3-5. In Lancashire the mean ratio is 1 to 3-5, but in 

 individual cases it may be much higher, even 1 to 55. These repre- 

 sent heavy loads pulled short distances by specially heavy horses 

 and for a small number of hours only, whereas the ratio of 3*5 

 represents eight working hours a day on good roads, though moder- 

 ately hilly. 



Seventy years ago Stewart put the load for slow draught at 22 to 

 30 hundredweight, cart included. A large contractor at Manchester, 

 in his evidence before the Strathnairn Committee forty years ago, 

 stated that nothing beyond 25 hundredweight for ordinary draught- 

 work (exclusive of the cart) should be placed behind any horse, 

 no matter whether the roads be good or bad. This is in the ratio of 

 1 to 3" 4, and supports the correctness of this proportion. For light 

 draught a load of 15 hundredweight, and for heavy draught one of 

 from 20 to 25 hundredweight, in both cases exclusive of the 

 vehicle, appears to be an average amount. The vehicles are heavy, 

 one of two wheels weighs from 7 to 1 1 hundredweight, while a four 

 wheel waggon weighs about 15 to 16 hundredweight. 



The following tables present a physiological statement of the 

 question of draught for an ordinary working day of eight hours : 



* ' The Maximum Muscular Effort of the Horse,' Journal of Physiology, 

 vol. xix., 1896. 



t The writer is indebted to Mr. Mattinson, F.R.C.V.S., A.V.C.(S.R.), and 

 Captain W. L. Harrison, F.R.C.V.S., A.V.C. (T.F.), for several observa- 

 tions and much valuable information. 



