178 Description and Use oj the

is a determinate space or interval of time'between the sun’s apparent passage fromone point of the ecliptic, until he returns tothe same point again, or from one equinoxto the same again, be it either vernal orautumnal.

Y/e take for our radix the autumnalequinox, anno 706 of the Julian period,which we call anno mundi o, and computefrom Thursday Oct. 25th, o h. o min. ornoon, the sun being then supposed to bein the first point of Libra on the meridianbefore mentioned, and vertical to that pointof the equator, which lies 156 degrees westof Greenwich.

And also in the meridian of Greenwich,Oct. 25th. 10 h. 24 m. upon the 298thday from the calends of January.

The tropical year thus reckoned exceedsthe Egyptian year 5 h. 49 min. and is but11 minutes short of the Julian year; somuch being annually allowed for the retro-cession of the equinox, consequently the.mean length of a tropical year is d. 5 h.49 min.

We are induced to measure time by thisquantity, because astronomers unanimously

agree,