"He shall turn the heart of the fathers towards the children, and the heart of the children to their fathers."—Malachi iv.
823. Why do the stripes upon a marble disappear when it is spun with great velocity?
Fig. 28—MARBLE SPINNING RAPIDLY.
Because, as in the case of the humming-top, the different parts of the surface are brought so rapidly in succession to the sight, that they deface or confuse the impressions upon the retina.
824. Why are rings most perceptible at the opposite points, or poles, of the marble?
Because the point, or pole, upon which the marble spins, and that which corresponds to it, on the upper surface, travel less rapidly than the central portions, which being of a larger circumference, pass through a greater amount of space, in the same period of time. The stripes at the poles of the marble, are, therefore visible, while those at its equator are imperceptible. (See [522].)