From parallel two-faced lines: Leading ends cast back and single hinge with trailing ends, then these two spread. The leading centers follow the ones beside them in a larger loop to the farther center of a new two faced line that is forming. Meanwhile, the trailing centers "do like a Tag the Line" and step into the remaining center spot of the new two faced line. Eclipse can also be done from Parallel Waves (leading ends cast back, leading centers start to loop out on own side); and from Column formation: First dancer casts back to third dancer; second dancer follows first; first and third single hinge and spread and the second dancer goes to the farthest center; The fourth dancer steps forward, does a "quarter zoom" and steps into the other center of a two-faced line.
Gus Greene 1975
This definition is from The Handbook of Modern Square Dancing by Jay King.
It is provided here for informational and educational purposes only.