Rule of thumb

Posted by ESC on November 14, 2001

In Reply to: "Grease monkey" posted by ESC on November 14, 2001

: : I am trying to find out the meaning and origin of the phrases "grease monkey" and "rule of thumb" I am using them in a current paper for my masters degree so I need credible sources. Can anyone help?

: "grease monkey - n. a mechanic, esp. one who works on automobiles or airplanes. 1928 Gravatt "Pioneers" 251: All the way down the line.from skilled draftsmen in a polished office to the 'grease monkeys' with blackened faces and smeary over-alls." From the Random House Historical Dictionary of American Slang, Volume 1, A-G by J.E. Lighter, Random House, New York, 1994. Page 959.

"rule of thumb means a rough or guesswork estimate, based more upon experience than on precise measurement.There are two theories about the origin of this expression. The more logical theory is that it comes from the frequent use of the lower part of the thumb (roughly equal to one inch in the average adult male) as a crude measuring device. However, some authorities trace the phrase to a practice once common among brewmasters. In the days when beer was truly beer, not the pasteurized soft drink that passes for beer today, the chief brewer sometimes tested the temperature of a batch of brew by dipping in his thumb. This technique was neither so accurate nor so hygienic as a thermometer check would be, but based on the brewmaster's long experience, this 'rule of thumb' would tell him how well the brewing was proceeding." From the Morris Dictionary of Word and Phrase Origins by William and Mary Morris (HarperCollins, New York, 1977, 1988). Page 500-501.