Celestial and Terrestrial Globes. 181

fore the Christian Æra, subtract it from4008; the remainder is the year from theradix.

Secondly, If any year since the ChristianÆra be given, add it to 4007, their sum isthe year from the radix.

Thirdly, Collect the days, hours, andminutes of retrocession, and autumnal equi-noxes from the table, according to thenumber of years from the radix, in thou-sands, hundreds, tens, and units; add theseinto two sums, the first will be the retro-cession, the second the time of the equinoxin that meridian which lies 156 degreeswest of Greenwich Observatory; to whichadd 10 h. 24 m. and you obtain the time atGreenwich.

This method will serve for any othermeridian also, if you add its difference intime from the fixed meridian.

Solar tropical years thus reckoned be-gin and end at the autumnal equinox, andall Julian years begin and end at the ka-lends of January *.

N 3 In

* The kalends of January begin from the noonof the preceding day ; that is, from the noon of theday before the first day of January.