EQUATION OF

See also:

• TIME (0. Eng. Lima, cf. Icel. timi, Swed. timme, hour, Dan. time; from the root also seen in " tide," properly the time of between the flow and ebb of the sea, cf. O. Eng. getidan, to happen, " even-tide," &c.; it is not directly related to Lat. tempus)
• TIME, MEASUREMENT OF
• TIME, STANDARD

TIME  , the difference between apparent time, determined by the meridian passage of the real sun, and mean time, determined by the passage of the mean sun . It goes through a double period in the course of a year . Its amount varies a fraction of a minute for the same date, from year to year and from one longitude to another, on the same day . The following table shows an average value for any date and for the Greenwich meridian for a number of years, from which the actual value will seldom deviate more than 20 seconds until after 1950 . The + sign indicates that the real sun reaches the meridian after mean noon; the — sign before mean noon . Table of the Equation of Time . m. s . m. s . m. s . Jan . I + 3 26 Mar . I +12 39 May I -2 55 6 5 45 6 it 35 6 -3 27 II 7 51 II 10 20 II -3 46 16 9 43 i6 8 58 i6 -3 51 21 II 19 II 7 30 21 -3 40 26 12 36 26 5 59 26 -3 16 Feb .

I +13 42 Apr. i + 4 9

June I -2 32 6 14 14 6 2 40 6 -1 44 lI 14 25 II + I 15 II —O 48 16 14 17 16—o 3 16+o 14 21 52 2I — I I2 21 I 19 26 i3 II 26 — 2 10 26 2 24 m. s . m. s . M 5 . July I +3 26 Sept . I+ 0 9 Nov . -16 i8 6 4 21 6 — i 28 6 -16 19 it 5 8 II — 3 10 I I -15 58 16 5 44 16—4 55 i6—15 15 21 6 8 21 — 6 41 21 -14 12 26 6 18 26 — 8 25 26 -12 49 Aug . I +6 io Oct . 1 -10 5 Dec . I— I I 7 6 5 47 6 —II 38 6 — 9 9 II 5 9 ` .