Page:Description and Use of a New Celestial Planisphere.pdf/24

19 and, are different parts, or portions of the celetial phere in all the different Latitudes upon this Globe; and in this parallel, the Circle of Perpetual Apparition is all that part of the celetial phere round the North Pole, that never ets below the Horizon, being from the parallel of 38° 28' declination Northward, and is always equal to the compliment of the Latitude; all the Stars within this Parallel revolve round and round the Pole, but never diappear, nor decend lower than the Northern part of the Horizon, and thee are ometimes called Circum-Polar Stars, and you will ee them, with their names in the Planisphere, by turning the Index round about;—by the same cause, the Circles of Perpetual Occultation, is, all thoe Stars, near, and round the South Pole, which never rie above the Southern part of our Horizon, from 38° 28' Declination Southward, to the South Pole.

But, this ubject will be better illustrated, and rendered apparent, by the olution of the following Problems with the Planisphere.

Problem 1. The day of the month, and hour of the day given, to rectify the Planisphere for ue, uppoe July 5th, at 4 hours, 36 minutes, P. M.?

Find the day of the month in the outermot circle, and bring the hour and minute on the index thereto, and it is done. This Problem is very hort, and olved in an intant; but its effects are very extenive and