Sourd

e. Fr. Literally means deaf, dull. It is variously applied by the French—viz. Lanterne Sourde , Fr. A dark lantern. Lime Sourde , Fr. A file which is made in such a manner, that you may separate pieces of iron without making any noise in the operation. It is likewise used in a figurative sense—to signify a person who says little, but is always meditating something mischievous or injurious to others. The French likewise say, sourdes pratiques , pratiques sourdes ; secret or underhand practices; sourdes menees , menees sourdes , secret or underhand ways. These terms are always used in a bad sense. In mathematics, the French call those quantities, quantites sourdes , which are incommensurable, that is, which cannot be exactly expre ed, either by whole numbers or by fractions. Thus the square root, or racine carree , of two is a quantite sourde .