Two sextuples of Skew Lines on the general Cubic Surface such that each line of one is Skew to one Line in the other set. Discovered by Schläfli.
See also Boxcars, Cubic Surface, Solomon's Seal Lines
Fischer, G. (Ed.). Mathematical Models from the Collections of Universities and Museums.
Braunschweig, Germany: Vieweg, p. 11, 1986.