may be sent by this means will depend (a) upon the force employed to start the waves, and (b) upon the lightness of the chip, or its sensitiveness to the motion of the waves. Moreover, if there were grass or other obstructions in the pond between the point where the waves are started and the pot where the chip is located, some of the energy would be absorbed in swaying the grasses: hence the effect upon the chip would not be so great, and the signalling distance would be lessened. Or if there were an
Fig 1.—Wave Motion in Water.
obstruction in the path of the waves, as, for instance, a protruding rock, the waves would be distorted by this obstruction; hence less energy would reach the chip.
It is also obvious that any number of chips might be placed at any number of points within the affected radius of wave motion, and all would be moved by the waves.
When it is considered that these water waves cover an ever-increasing area as the circles expand, and that the actual energy which disturbs the chip is an extremely small part of the total energy in the entire circular wave, it should be clear why so great an amount of energy is