218 Description and Use of the

setting precedes that on the meridian 90 de-grees, or six hours i and 180 degrees ortwelve hours that which is rising; and thatdegree of the equator, which is on the me-ridian under the elevated pole, is 180 de-grees distant from that point of it which ispasting the meridian.

PROBLEM XL VII.

To find the time of the right ascen-sion of the first point of Ariesupon any meridian.

288. We have already shewn by an easycalculus, how to find the times of equinoxto any meridian, but we have not yet strewntheir application to the right ascension of thefirst point of Aries.

The diurnal difference of right ascension,at the time of a vernal equinox, is 3 min.38 sec. which we have formed into a table,entitled, “ The horary difference in the“ motion of the first point of Aries at the" time of a vernal equinox to which isannexed* " A table of the difference of the

passage