This instrument is designed to plot a graph on a sheet of A4 paper showing the relation between slowly varying electrical signals on the X and Y inputs. There are potentiometer wires along the horizontal and vertical axes and servo systems move the pen to the balance position on each wire. The sensitivity ranges from 0.01 V per inch to 1.0 V per inch on each input, and the X input can be run as a time base with speeds 0.5 to 100 s per inch.
Such instruments were developed from the late 1950s, and high quality models like this one were in common use until superseded by computer-controlled instruments in the 1990s.
This instrument has a modified mounting to take more readily available pens.

Inscriptions / Translations:  7015B X-Y RECORDER
HEWLETT PACKARD
Serial no. 2042G02181