Though the maintenance of the centre of gravity is rendered more difficult in proportion to the height to which it is raised above the base, as my younger readers may have found when constructing a house of cards, this is not the case when any disturbance of the equilibrium can be counteracted immediately, as in the case of a stick balanced on the tip of the finger. A stick three or four feet long is more easily balanced on the finger than one much shorter, because the tendency to topple over can be counteracted by the movement of the finger in the direction in which it leans, so as to maintain the centre of gravity. Those who make an experiment of this kind for the first time will be apt to find that the balancing of a stick or a broom upon the finger is difficult, owing to the smallness of the base in proportion to the height of the centre of gravity, unless the eyes are directed towards the top. The stick is at rest at the base, and any deviation from the perpendicular must commence at the upper extremity. Keep your eye on the top, and you can balance a scaffold-pole or a ladder, if you can sustain the weight. Whatever difficulty there was in the feat of balancing a ladder, to the top of which a small donkey was attached, as exhibited in my juvenile days by an itinerating performer,—whence the saying, ‘Twopence more, and up goes the donkey!’—was due entirely to the weight of the animal; because, if it was properly attached to the ladder, the centre of gravity would be in precisely the same situation as if the ladder alone had to be balanced. In the animal world, the centre of gravity is invariably so placed as to produce an exact equilibrium and harmony of parts. Every animal furnished with legs is balanced upon them; so that in man the centre of gravity is the crown of the head. The reader may test this by leaning forward or laterally, with the arms by the side, and the legs straight, when a tendency to fall will be experienced, which can be counteracted only by extending an arm or a leg in the opposite direction. The art of balancing the body in extraordinary situations, as exemplified in the feats of rope-walkers and gymnasts, depends, therefore, on the same natural law as that which enables us to balance a stick upon the finger. The centre of gravity must be kept perpendicular to the rope or bar, any tendency to sway to the right or left being corrected by the arms, or by the balancing-pole, if preferred, by performers on the rope.