179 
Fie. 177.—Diagrammatic representation of the pendulum myograph. The smoked-glass plate, 
A, swings with a pendulum, B. Before an experiment is commenced the pendulum is 
raised up to the right and kept in position by the tooth, a, catching on the spring-catch, b. 
On depressing the catch, b, the glass plate Deine set free swings into the new position indi- 
cated by the dotted lines, and is held there by the tooth, a’, meeting the catch, b’. In the 
course of its swing the tooth, a, coming into contact with the projecting steel rod, c, knocks 
it to one side, into the position indicated by the dotted line, c’. The rod, c, is in electric 
continuity with the wire, x, of the primary coi] of an induction machine. In like manner 
