Micrometer
/maɪˈkrɒmɪtər/noun
A gauge that measures very small distances by the turn of a finely cut screw.
The Greek roots
Literally: “small measure”
The story of the word
Two devices share the name. William Gascoigne, working in Yorkshire in the late 1630s, mounted screw-driven pointers in a telescope eyepiece so he could measure how wide a planet looked, and the word for that instrument reached English in the 1660s. The workshop micrometer with its thimble and ratchet is the same trick moved to a bench. The unit spelled micrometre, a millionth of a metre, is a separate product of the metric system, which is why engineers say micron instead.
- How it travelled
- Ancient Greek → scientific coinage → English
- First recorded
- 1660s
Same family
In a sentence
Check it with the micrometer, not the calipers, if the tolerance is two hundredths.
The micrometer reads to a thousandth and the operator's thumb accounts for the rest.