Richard,
Don't be so quick to assume. In the early part of the last century the job of "Engine Wiper" or "Engine Washer" were entry level jobs into the Locomotive Fireman and Engineer's crafts.
The wiper was supposed to be in charge of wiping down the boiler jacket, and while doing that checking the sand and oil levels (which would also be checked again by the Fireman and Engineer). After serving a satisfactory amount of time doing this job, they would be invited to apprentice to a qualified fireman.
It was a legitimate part of the Engine Service Craft, albeit the lowest face on the totem pole.
Rick Steele