ON DRAUGHT. 417 



LurvUon of labour in hours. Velocity, miles per hour. Eflect prod'iced. 



2 5|- 578 



3 4} 709 



4 3f 813 



5 . ... 3i 909 



6 3 1000 



7 2f 1063 



8 2f 1110 



To attain hiirher velocity, it is necessary still further to reduce the load, 

 and the next Table is calculated upon the supposition of the strain being 

 oniy one half the last, viz: 62^ lbs.; this is about the average exertion of 

 eu.;h horse in a four-horse heavy stage-coach. 



Eflect produced. 



.... 613 



.... 534 



.... 434 



.... 307 



In mails or light coaches, where ten, eleven, and even eleven and a half 

 3r twelve miles an hour is attained, the average strain of each horse is 

 barely 40 lbs., and the effect produced, or value of work done, not much 

 more than one-half the above. 



It must be remembered, that these Tables are all calculated upon the 

 supposition of the road being good, and the work not such as to cause any 

 immediate injury to the animal, and is adapted only to the average quality 

 of horses. They are not therefore, at once applicable as data for calcula- 

 tions in all ordinary cases, but only serve to show the comparative forces 

 which may be exerted under difl^erent degi-ees of speed. The results or 

 effects of this force will always be influenced by the quality of the resist- 

 ance, as we have already observed in the cases of slow travelling; but in 

 rapid travelling, the power is much more expensive, owing to the great 

 loss which we see, by the Tables, is sustained by increased velocity ; and 

 it is, therefore, the more important to study well the means of applying the 

 power in question. 



In this rapid travelling, the bad consequences of a uniform and constant 

 strain is still more felt by the horses, and the necessity of occasional relief 

 is still more urgent than at low velocities. It is universally admitted by 

 horse proprietors and postmasters, whose interests make them peculiarly 

 sensible on this point, that a flat piece of road is more destructive of horses 

 than the same length of road where gentle rises and alternate flat and 

 swelling ground occur; and that a long hill is easier surmounted where 

 there are occasional short levels, and even descents, than when the whole 

 is one uniform descent. 



It only remains for us, before we dismiss the subject of the moving 

 power, to consider the particular mode of applying it, or the manner of 

 harnessing the horses. 



Under this head, comes the question of the best direction of the traces, 

 '.)r, as it has generally, but less clearly, been called, the angle of inclina- 

 •ion of the line of traction. This question appears to have been always 

 considered one of the greatest importance : the point has been frequently 

 discussed, and various opinions have been advanced ; some having reconi. 

 mended it to be horizontal, and others inclined; and, as they have each ir 



