What are bench chemists?

Some articles on chemists, bench chemists:

Du Pont Central Research
... well over 50 years and provided a steady supply of well-trained chemists.) Robert Grubbs, who shared the Nobel Prize with Schrock, consulted for many years ... At its founding, the division of labor in CRD was “management,” “bench chemists,” and “technicians,” with the management and bench chemists having separate but overlapped ... or promotional levels for the “bench chemists,” yet there was a single undistinguished title ...