LATIN DICTIONARYLexicon Latīnum
Academy · Antiquities

Hora

ὥρα

Hora (ὥρα), in the signification of hour, that is, the 12th part of the natural day, did not come into general use among the ancients until about the middle of the second century B.C. The equinoctial hours, though known to astronomers, were not used in the affairs of common life till towards the end of the fourth century of the Christian era. The division of the day was marked very roughly by the position of the sun (Varro, L. L. 6.89). As the division of the natural day into twelve equal parts, both in summer and winter, rendered the duration of the hours longer or shorter according to the different seasons of the year, it is not easy, with accuracy, to compare or reduce the hours of the ancients to our equinoctial hours. The hours of an ancient day would only coincide with the hours of our day at the two equinoxes. [DIES and HOROLOGIUM] As the duration of the natural day, moreover, depends on the polar altitude of a place, our natural days would not coincide with the natural days in Italy or Greece. Ideler, in his Handbuch der Chronologie, has given the following approximate duration of the natural days at Rome, in the year 45 B.C., which was the first after the new regulation of the calendar by J. Caesar; the length of the days is only marked at the eight principal points in the apparent course of the sun.

Days of the year. 45 B.C.Their duration in equinoctial hours.
Dec. 238 hrs. 45 minutes.
Feb. 69 hrs. 50 minutes.
March 2312 hrs. 0 minutes.
May 914 hrs. 10 minutes.
June 2515 hrs. 6 minutes.
August 1014 hrs. 10 minutes.
Sept. 2512 hrs. 0 minutes.
Nov. 99 hrs. 50 minutes.

The following table contains a comparison of the hours of a Roman natural day, at the summer and winter solstice, with the hours of our day.

SUMMER SOLSTICE.
Roman Hours.Modern Hours.
1st hour4 o'clock,27 minutes0 seconds.
2nd hour5 o'clock,42 minutes30 seconds.
3rd hour6 o'clock,58 minutes0 seconds.
4th hour8 o'clock,13 minutes30 seconds.
5th hour9 o'clock,29 minutes0 seconds.
6th hour10 o'clock,44 minutes30 seconds.
7th hour12 o'clock,0 minutes0 seconds.
8th hour1 o'clock,15 minutes30 seconds.
9th hour2 o'clock,31 minutes0 seconds.
10th hour3 o'clock,46 minutes30 seconds.
11th hour5 o'clock,2 minutes0 seconds.
12th hour6 o'clock,17 minutes30 seconds.
End of the day7 o'clock,33 minutes0 seconds.
WINTER SOLSTICE.
Roman Hours.Modern Hours.
1st hour7 o'clock,33 minutes0 seconds.
2nd hour8 o'clock,17 minutes30 seconds.
3rd hour9 o'clock,2 minutes0 seconds.
4th hour9 o'clock,46 minutes30 seconds.
5th hour10 o'clock,31 minutes0 seconds.
6th hour11 o'clock,15 minutes30 seconds.
7th hour12 o'clock,0 minutes0 seconds.
8th hour12 o'clock,44 minutes30 seconds.
9th hour1 o'clock,29 minutes0 seconds.
10th hour2 o'clock,13 minutes30 seconds.
11th hour2 o'clock,58 minutes0 seconds.
12th hour3 o'clock,42 minutes30 seconds.
End of the day4 o'clock,27 minutes0 seconds.

Also from Plautus (Pseud. 1307) we see that an hour in winter was shorter than one in summer.

The custom of dividing the natural day into twelve equal parts or hours lasted, as we have observed, till a very late period. The first calendarium in which we find the duration of day and night marked according to equinoctial hours, is the Calendarium rusticum Farnesianum. (Ideler, Handbuch der Chron. ii. p. 139, &c.; Graev. Thesaur. Ant. Rom. viii.; Mus. Borb. ii. pl. 44.)

Another question which has often been discussed is whether in such expressions as prima, altera, tertia hora, &c., we have to understand the hour which is passing, or that which has already elapsed. From the construction of ancient sun-dials on which the hours are marked by eleven lines, so that the first hour had elapsed when the shadow of the gnomon fell upon the first line, it might seem as if hora prima meant after the lapse of the first hour. In Pers. 3.4, quinta dum linea tangitur umbra, the end of the fifth hour is clearly meant. But the manner in which Martial (4.8), when describing the various purposes to which the hours of the day were devoted by the Romans, speaks of the hours, leaves no doubt that the expressions prima, altera, tertia hora, &c., mean the hour which is passing, and not that which has already elapsed. Hence hora nona cenare means to dine when the ninth hour is beginning, i. e. about 2 P.M. (Becker, Gallus, ii.3 351= Becker-Göll, 2.406 ff.; Mayor on Plin. Ep. 3.1, 8.)

From William Smith (ed.), Dictionary of Greek and Roman Antiquities. Text provided under a CC BY-SA license by Perseus Digital Library, http://www.perseus.tufts.edu, with funding from the National Endowment for the Humanities and Tufts University. Data accessed from https://github.com/PerseusDL/canonical-pdlrefwk/ on 17 October 2026.