When the marble strikes upon the earth, a new influence is exerted upon it, which is the friction of the earth upon the surface that comes in contact with it; but the upper part of the marble, being free, overcomes the friction acting upon the lower part, and thus the marble continues to progress, until the applied force which projected it is expended.
"Better is a poor and a wise child, than an old and foolish king who will no more be admonished."—Ecclesiastes iv.
819. Why does a striped marble appear to have a greater number of stripes when rolling, than when at rest?
Because the stripes are presented in rapid succession to the eye; and as the eye receives fresh impressions of stripes before the previous impressions have passed away, the stripes appear multiplied.
Fig. 26.—MARBLE AT REST.