Contrate wheel

( Mach.) See CROWN-WHEEL. Contravalla'tion, n. [Fr. contrevallation; Lat. con tra, and vallo, vallatus, to fortify.) ( Fortif.) An intrenchment formed by the besiegers between their camp and the place besieged, to secure themselves and check the sallies of the garrison. The line of contravallation is thus, as the name implies, a sort of counter -fortification. Contrava'rient, a . ( Math .) Applied to any quantic so derived from a given system of quantics as to be equal, in virtue of any uni modular and linear transformations of its variables, to the quantic derived in the same manner from the system to which the given one is transformed by linear substitutions reciprocal, or opposite, to the first.