bas·cule 
(băskyl)
(băskyl)n.
A device or structure, such as a drawbridge, counterbalanced so that when one end is lowered the other is raised.
[French, seesaw : bas, low (from Old French, from Medieval Latin bassus) + cul, bottom (from Old French, from Latin cūlus, rump; see (s)keu- in the Appendix of Indo-European roots).]
bascule