ON DRAUGHT. 559 



to the direction of motion ; and its power is diminished at any inclination of 

 that line, in the proportion of the radius of the wheel to the cosine at the angle. 

 When obstacles frequently occur, it had better, perhaps, receive a small incli- 

 nation upward, for the purpose of acting with most advantage when these are 

 to be overcome. But it is probable, that different animals exert their 

 strength most advantageously in different directions ; and, therefore, practice 

 alone can determine what precise inclination of the line is best adapted to horses, 

 and what to oxen. These considerations are, however, only applicable to 

 cattle drawing immediately at the carriage ; and the convenience of their 

 draft, as connected with the insertion of the line of traction, which continued, 

 ought to pass through the axis, introduces another limit to the size of the 

 wheels. 



" Springs were in all likelihood first applied to carriages, with no other view 

 than for the accommodation of travellers : they have since been found to answer 

 several important ends. They convert all percussions into mere increase of 

 pressure ; thus preserving both the carriage and the materials of the roads from 

 the effect of blows; and small obstacles are surmounted when springs allow the 

 frame and wheels freely to ascend, without sensibly moving the body of the 

 carriage from its place. 



"If the whole weight is supposed to be concentrated on springs very long, 

 extremely flexible, and with the frame and wheels wholly devoid of inertia, 

 this paradoxical conclusion will most certainly follow : that such a carriage may 

 be drawn over the roughest road without any agitation, and by the smallest 

 increase of force. 



" It seems probable that springs, under some modification of form and material, 

 may be applicable with advantage to the heaviest waggon." 



And there can be no doubt, that, in the words of the writer, the application 

 of springs would be highly advantageous. At high velocities, as we have before 

 said, the effect of springs is still greater. What we have instanced as regards 

 springs, is generally well known and understood. All stage-coaches, and many 

 travelling-carriages, hang upon grasshopper springs, which allow of perpen- 

 dicular without any longitudinal action. It would be much to the interests of 

 horse masters if the mode of suspending^post-chaises were a little more attended 

 to. The more elasticity, or in other words, the more action, there is in grass- 

 hopper springs, the more effect it will produce in diminishing the draught : with 

 a C spring a very contrary effect is produced. 



A carriage hung upon C springs may certainly be made the most comfortable 

 to the rider, but all the ease that can be required, and much more than is found 

 in the generality of post-chaises, may be obtained by well- constructed grasshopper 

 springs, and with considerable advantage to the horses. 



The practice of loading coaches as high as possible to make them run light, 

 as the coachmen have found by experience, is only a mode of assisting the 

 springs. The mass being placed at a greater height above the wheels, at the 

 extremity of a long lever, is not so easily displaced laterally by any motion of 

 the wheels, which, therefore, rise and fall on either side as they run over the 

 stones, acting only on the springs, which restore the full pressure and velocity 

 in descending, from the obstacle which was imparted to them in ascending, and 

 without producing any sudden concussions upon the load, which swings to and 

 fro with long easy movements. It is possible, *ha* *he weight, being thus 



swung from side to side, may, upon good roads, diniimsii the draught, as it is in 

 fact generally running upon two of the wheels ; while, in the other direction, it 

 equally admits of the front and hind wheels successively passing over any impe- 

 diments ; and yet, by the manner in which it is fixed upon the springs, it doea 

 not admit of any longitudinal elasticity 



