Celestial and terrestrial Globes. 219

*< passage of the first point of Aries over the“ meridian for every day in the year.”

The use of the tables of rightascension.

289. Having found the time of any ver-nal equinox, and transferred it from thefixed to your own meridian by the additionof your meridian distance,

Take out of the table of horary diffe-rences, the motion answering to the hoursand minutes of the time of the vernal equi-nox, and their sum will be the time of thepassage of the first point of Aries over thatmeridian ; the day on which, but before, theequinoctial intersection happens.

N. B. In taking out the numbers fromthis table, reject the thirds, if they are underthirty; if they exceed thirty, add one to theminutes found in the table.

A. D. 1769, the vernal equinox falls onMarch 19th, 19 h. 37 min.

min. sec.hours 19 2 53

min. 37 o 6

Right ascension of T 0 ,up -7 „

on the equinoctial day J 2 ^ noon '

A, Da