A Carious Optical Delusion.

Manawatu Herald, 4 August 1896, Page 4

A Carious Optical Delusion.

If we place a ball, a cylinclor, or any other rolling body on an inclined plane, we all know what will happen — it will roll down hill, obedient to the force of gravity. The following experiment appears to contradict the principle of the inclined plane; but, on tho contrary, we shall see that it confirms the customary law of nature: Glue a couple of small lamp shades securely together lay their bases, or they may be two cones of cardboard. Now with two smooth walking sticks construct an inclined plane by plaoing them on volumes

Of unequal height, as in the drawing, observing, however, that they form an acute angle with each other, whose apex falls beyond the smaller book. Place this double cone near the lower angle, close to the bottom of the inclined plane, and, to your astonishment, instead of seeing it roll down tho remainder of tho distance, it will appear to mount tho reverse way and steadily revolve up hill. But you will quickly arrivo at the philosophy of the thing when you appreciate the fact that tho cone itself is really going down the hill, for as tho anglo between the walking sticks widens it allows the center of gravity of the cone to descend lower and lower. It is but a curious optical illusion, not a contradiction of the laws of gravity.