Equation of Time
Preserved but no longer current.
The difference between mean and apparent time — i.e. the difference between the time as shown by a perfect clock and that indicated by a sundial. The greatest difference is at the beginning of November, when the sun is somewhat more than sixteen minutes slow. There are days m December, April, June, and September when the sun and the clocks agree.
Era: ca. 1898 (Victorian)
Sources & notes
Reproduced from Brewer’s Dictionary of Phrase and Fable (1898 edition, public domain; archive.org, retrieved 2026-07-31; OCR text, minor errors possible). Reflects the scholarship and attitudes of its era.
Common questions
What does “Equation of Time” mean?
The difference between mean and apparent time — i.e. the difference between the time as shown by a perfect clock and that indicated by a sundial. The greatest difference is at the beginning of November, when the sun is somewhat more than sixteen minutes slow. There are days m December, April, June, and September when the sun and the clocks agree.
Is “Equation of Time” formal or informal?
No register label has been reviewed yet — treat it as neutral and check the usage notes above.