Kymograph n. : An instrument for measuring, and recording graphically, the pressure of the blood in any of the blood vessels of a living animal; -- called also kymographion.

Example:
what is the use of the rotating drum in the Kymograph?

Taxonomy
Kymograph, free encyclopedia, phenomena, measure, search, wave, graphical representation, spatial position, over time, axis, drum, sheet of paper, back and forth, recording, motion, pressure, German physiologist, 1840s.

Defination from the web:
Kymograph. From Wikipedia, the free encyclopedia. Jump to: navigation, search. A kymograph (which means 'wave writer') is a device that gives a graphical representation of spatial position over time in which a spatial axis represents time. ...