noun: successive change from one thing or state to another and back again
noun: being regularly exchangeable
Keely
"The introductory impulse represents the sympathetic chord of unity to polar attraction. When this is given, the polar outreach is immediately established in the polar circuit, which seeks to assimilate itself to the anti-polar, or triple groupings; but as the alternation of the two circuits represents a condition of sympathetic antagonism (as 8 is to 9), an intensified differentiated wave motion is induced between the two, thus developing eight alternations, or waves, to one revolution of the device." [The Operation of the Vibratory Circuit]
See Also
alternation
heart beat
heartbeat
rhythmic balanced interchange