duated edge of the quadrant. The degree of the quadrant, cut by the star, is its Latitude; and the sign and degree cut on the Ecliptic, is its Longitude. PROBLEM III.-To find the place of a star, planet, Moon, or a comet, on the globe, its right ascension and declination being given. Bring the given degrees of right ascension to the brass meridian; and under the given declension, on the brass meridian, the star, or place of the planet, will be found. PROBLEM IV. The day, hour, and Latitude of a place being given, to find what stars are rising, setting or culminating, &c. Elevate the pole to the Latitude of the place; bring the Sun's place in the Ecliptic to the brass meridian; set the index to 12; if the given time be before noon, turn the globe eastward, till the index has passed over as many hours as it wants of 12; and if it be afternoon, turn the globe westward, till the index has past over as many hours as it is past 12; then all the stars west of the horizon will be setting; all those east of it will be rising; those under the brass meridian will be culminating, &c. PROBLEM V. To find when any given star will rise, set, or come to the meridian. Elevate the pole to the Latitude of the place; bring the Sun's place in the Ecliptic to the meridian; set the index at 12; turn the globe till the given star, or planet, comes to the east of the horizon, and the index will shew the time of its rising; bring the star to the meridian, and you have the time it crosses the meridian; bring it to the west of the horizon, and you have the time of its setting. PROBLEM VI. To find the distances of the stars in degrees from each other. Place the quadrant of altitude on the two stars whose distance you wish to measure; so that the division marked O be on one of them, and the degrees between them will show their distance. If the right ascension or declination of a heavenly body is given, how can it be found? How can the length of the longest day in different places within the Arctic circle be found on the globe? If the day, the hour, and Latitude of a place be given, how find what stars will then be rising, setting, or culminating? How can it be found when any given star will rise, set, or come to the meridian? How can the distance of stars from each other be found in degrees? PROBLEM VII.-To find the altitude of a star at any given time. Rectify the globe for the latitude of the place. Bring the sun's place in the ecliptic to the meridian, and set the index at 12. Turn the globe till the index points to the time proposed. Then with the quadrant of altitude, or dividers, take the nearest distance of the star from the horizon; the number of degrees on the quadrant, or in the extent of the dividers applied to the equator, shows the altitude. PROBLEM VIII. Having the altitude of a star given, to know the time of night. Rectify the globe for the latitude of the place. Bring the sun's place in the ecliptic to the meridian, and set the index at 12. Turn the globe till the star comes to the altitude proposed; the index will point to the hour required. PROBLEM IX.-The Latitude of a place being given, to place the globe so as to represent the appearance of the heavens at any hour proposed. Rectify the globe for the Latitude of the place. Bring the sun's place in the ecliptic to the meridian and set the index at 12. Turn the globe eastward for the forenoon, westward for the afternoon, till the index points to the given hour. The globe will then represent the appearance of the heavens at the time proposed. A familiar use of the globes is recommended to the student. It will greatly improve his knowledge of geography and astronomy. It will make him more interested in contemplating the objects of the visible heavens, a delightful and innocent amusement for the evening, or the most lonely hours of night. What is much more; by observation on the celestial canopy, he must be irresistibly led from the greatness of the scenery to the contemplation of the immensity and infinite goodness of the GREAT AUTHOR." VOSE. What is the altitude of Procyon, as seen at Washington, February 1st, at 7 o'clock, P. M. What is the altitude of Vege, as seen from New-Haven, September 26, at 2 o'clock, A. M.? ́ What is the time of night at Philadelphia, on the 20th of October, when the largest star of the Pleiades is 150 above the eastern horizon. What is the time of night at Boston, on the last day of August, when Arcturus is 100 above the western horizon? What will be the appearance of the heavens at Washington, March 20th, at 7 o'clock, P. M LATITUDE AND LONGITUDE OF SOME OF THE PRINCIPAL PLACES IN THE UNITED STATES. The Longitudes are reckoned from Greenwich. Seats of Government are in Italic Letters. Length of the longest and shortest days in some of the principal Cities of the United States. L. D. S. D. h. m. h. m. 16 53.5 7 6.5 Washington, New-Orleans, L. D. IS. D. h. m. h. m. 14 43.8 9 16.2 14 35.5 9 24.5 14 18.6 9 41.4 14 10.2 9 49.8 14 5.8 9 54.2 13 55.8 10 4.2 13 54.9 10 6.1 13 32.1/10 27.3 |