104 CENTRE OF GRAVITY. 



circular tower which has no parapet, slope outwards, 

 it is not only difficult but highly dangerous to walk 

 fast round them ; but if they slope inwards, they are 

 safer and more easy than if one were walking in a 

 straight path having the same width. Upon a simi- 

 lar principle though there the forward motion of 

 the centre of gravity has more to do in the matter 

 if a circular turn in a road slope outwards, a coach, 

 if moving rapidly, is apt to be overturned or the 

 passengers flung off towards the outside, but if, on 

 the contrary, the road at such a place slope inwards, 

 it is safer than if it were level. On this principle, 

 coaches are much more endangered by passing 

 rapidly loops of road at the hips of hills, than simi- 

 lar loops at the heads of valleys. Thus, we perceive 

 that there is no little information even in that which 

 to those who " see things but do not look at them" 

 appears to be a merely accidental path, and that 

 shored lead us to be careful to " look at every thing 

 we can see ;" and if we once do that, we are inde- 

 pendent of the lessons of other people. 



But we further see that there is, in the nature of 

 the surface over which we proceed, a tendency to 

 turn us from the purposed direction of our path ; 

 and if we do not observe the variations of surface 

 which act mechanically upon our centre of gravity, 

 and occasion these deviations from the straight line, 

 we never can get to our intended place by the 

 shortest road, and very often we cannot get to it 

 at all. The inequality of our steps increases this 

 tendency to deviate ; for if, upon level ground, we 

 take short steps with the one leg, and long steps 

 with the other, it is altogether impossible for us to 

 keep the straight line ; and if we are on a slope, it 

 is just as impossible for us to prevent ourselves 

 from curving down that slope, if we do not take 

 short steps with the higher leg and long steps with 

 the lower; and if we would gradually climb the 

 slope with the least exertion, the higher leg must 



