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Horizon. Mind the ſame rule with all the fixed Stars, (but the Moon), and the ſwifteſt of the Planets will require a reduction in their places in this Problem.
Problem 18. To find at what hour a Star riſes on any day, ſuppoſe Oct. 14th. What time doth the Bull's Eye riſe?——Bring the Star to the Horizon, and ſee what hour and minute points to the day propoſed, and it is found to be 12 minutes before Eight at night, and ſets 12 minutes before Ten in the morning.
Problem. 19. To learn to know the Stars by ſight, at any hour, by the help of the Planisphere. Suppose July 20th. at 10h &c. P. M. you are out of doors, and rectify the Planisphere to that hour; then ſuppose yourſelf to ſtand under that part of the heavens where is marked the Zenith of London in the Planisphere, and you will ſee the Dragon's Head in the Vertex, Lyra South by Eaſt, the Stars of Pegasus nearly Eaſt, with from ten to twenty degrees of Altitude, the Great Bear Weſt North Weſt; Arcturus Weſt South Weſt; the Virgin's Spike nearly ſetting Weſt-South-Weſt; Cor-Scorpio South-South-Weſt; Atair in the Eagle South-South Eaſt; Perseus and Capella near the northern Horizon; and you may ſee the names of the reſt in the Planisphere, that are then above the Horizon; and by varying the time of the year in your obſervation, you will eaſily ſee, and learn the names of them all.—This is a uſeful Problem, and ſhould often be repeated.
