An inexpensive modification of a commercial mass spectrometer is described which permits linear display of ion intensity vsm/eon an X‐Y recorder. Its evaluation shows that the major limitations arise from recorder specifications. For magnetically scanning instruments, mass assignments can be made within ±0.006% utilizing the maximum zero offset of 85% of the largest mass of interest. Peak positions are independent of scanning speed up to 30m/eunits/min and can be assessed within 0.1% of the mass range covered.