Lever

(lē'vr.) [From Fr. lever, to raise.] (Mech.) The name given to any bar, straight or curved, AB, resting on a fixed point or edge c called the fulcrum. The forces acting on the lever are the weight or resistance Q, the power P, and the reaction of the fulcrum. Sinco these are in equilibrium, the resultant of P and Q must act through C, for otherwise they could not be balanced by the reaction. Draw cb at right angles to QB and ca to PA produced; then observing that PXca, and QXcb are the moments of P and Q with respect to c, and that they have contrary signs, we have by (38), PX ca= Qxcb; an equation commonly expre ed by the rule, that in the L. the power is to the weight in the inverse ratio of their arms. L. are divided into three kinds, ac-C cording to the position of the fulcrum with respect to the points of application of the power and the P weight. In a lever of the first kind the 2 fulcrum is between the power and re-Fig. 443. LEVER. si stance, as in Fig. 443. In a lever of the second kind the resistance is between the power and the fulcrum, as in a wheelbarrow or a pair of nut-crackers; in a lever of the third kind the power is between the fulcrum and the resistance, as in a pair of tongs or the treadle of a lathe. Le'ver, CHARLES JAMES, an Irish novelist, B. in Dublin, 1809, and one of the most popular of living authors, has produced quite a legion of well-known standard novels of military and social and political life. In 1867 he was appointed British Consul at Trieste. [s. 540]