True Noon

True Noon is the time of noon given by a chronometer which keeps regular time all through the year. The sun does not keep regular time, the time between two successive noons as indicated on a sundial not being exactly 24 hours. The time indicated by the dial is known as apparent time. The true and apparent noons coincide four times a year - on April 14, June 14, September 1, and December 25. From December 25 to April 14 the true noon arrives before the apparent noon, the greatest difference occurring on February 11th, when the chronometer indicates 12 o'clock, while the sundial points to 11 hours 45 mins. 28 secs. Between April 14 and June 14 the sundial is ahead, and on May 14 the difference is 3 mins. 55 secs, Between June 14 and September 1 the sundial lags behind, and on July 26th it shows a difference of 6 mins. 12 secs. From September 1 to December 25 the dial is again in front, so that when the chronometer indicates noon the sundial shows 12 hours 16 mins. 18 secs. p.m. [STANDARD OF TIME, EQUATION OF TIME.]