PULSE, is also used for the stroke with which any medium is affected by the motion of light, sound, &c. through it.
Sir Isaac Newton demonstrates, that the velocities of the pulses in an elastic fluid medium (whose elasticity is proportionable to its density) are in a ratio compounded of half the ratio of the elastic force directly, and half the ratio of the density inversely; so that in a medium whose elasticity is equal to its density, all pulses will be equally swift.