CHAFTEE II. 



THE ANGLE OF TRACTION — THE COLLAR — THE HAMES 



THE TRACE-— THE POLE AND POLE-CHAINS THE 



HEIGHT OF THE WHEEL. 



The angle of Traction/' — The mathematical or 

 mechanical law which informs us that a given force, 

 when applied precisely in the direction in which 

 motion is desired to be effected, confers greater power 

 than when applied under an angle, is so perfectly con 

 sonant with our everyday experience that it requires 

 no further demonstration. We may, however, just 

 as well say that as a given force applied directly up- 

 wards to a wheel would only tend to lift it up, or 

 directly downwards to press it against or into the 

 ground, so in proportion as it comes to be applied 

 further and further away from cither of these two 

 directions — that is to say, the perpendicular line up 

 and down — the more power of rolling the wheel 



* The idea of any importance being fairly attributable to an 

 adjustment of the angle of traction has beeu recently sneered 

 at by some of our "rule of fcliumb " pliilosoi3bers,on the ground 

 that the celebrated old coachmen on the Bath, Brighton, and 

 other roads, knew nothing of it. It may be taken for granted 

 that the}'- probably never heard of the existence of such a 

 thmg; but that does not prove that they were indifferent to the 

 position of their traces, or unaware of the fact that their teams 

 or single horses required certain adjustments to be made of the 

 harness, the traces and other parts of the harness, and these 

 they did make, not indeed on theoretical grounds, but from 

 personal observation and experience. The sneerers should 

 prove, if they can, that the results of these observations and 

 experiences were at variance with the theory set forth above, 

 which is grounded as all theories should be, on still more ex- 

 tended experiences ; by doing so they would extend our know- 

 ledge. 



