A, An ivory button which is pressed on the skin over the radial artery by a metal spring.
B, A continuous screw which works against the cogwheel
C. By rotating B, the lever
D is raised to a position in which its point scratches the travelling-plate
E (covered with blackened paper).
F, A box containing clockwork which moves E.
G, A screw by means of which the pressure of the spring is adjusted to the force of the pulse.