Definition of "æquation"

Whereas in Arithmetick Questions are only resolv'd by proceeding from given Quantities to the Quantities sought, Algebra proceeds in a retrograde Order, from the Quantities sought as if they were given, to the Quantities given as if they were sought, to the End that we may some Way or other come to a Conclusion or "Æquation", from which one may bring out the Quantity sought. And after this Way the most difficult problems are resolv'd, the Resolutions whereof would be sought in vain from only common Arithmetick. Yet Arithmetick in all its Operations is so subservient to Algebra, as that they seem both but to make one perfect Science of Computing; and therefore I will explain them both together.

1707, Isaac Newton, translated by Joseph Raphson, Arithmetica Universalis [Universal Arithmetic]‎

The principal clocks in this city ſtrike the hours from one to twelve progreſſively from the riſing of the ſun, and begin again after ſun‐ſet, which at firſt puzzles ſtrangers; but by the table of the æquation of time, publiſhed here, this may be reduced to the common method of calculating time.

1757, Johann Georg Keyssler, Travels through Germany, Bohemia, Hungary, Switzerland, Italy and Lorrain, Volume IV, second edition, Letter XCII, page 178