Hoist on his own petard. Caught in his own trap, involved in
the danger he meant for others. The petard was a conical instrument of
war employed at one time for blowing open gates with gunpowder. The
engineers used to carry the petard to the place they intended to blow
up, and fire it at the small end by a fusee. Shakespeare spells the
word petar. “'Tis the sport to have the engineer hoist with his
own petar.” (Hamlet, ii.
4.)
“Turning the muzzles of the guns Magdalawards, and getting a piece of
lighted rope [the party] blazed away as vigorously as possible ... and
tried to hoist Theodore on his own petar.” Daily paper.
More on Petard' from Infoplease:
See a map of "" in the Visual Thesaurus
