a planet, or of a comet, being given, to find its place The right ascension and declination of a star, the moon, on the globe.

Rule. Bring the given degrees of right ascension to that part of the brass meridian which is numbered from en declination on the brass meridian, you will find the the equinoctial towards the poles; then, under the giv star, or place of the planet.

Examples. 1. What star has 261° 29' of right ascension, and 52° 27' north declination?

Answer. ß in Draco.

*The places of the stars on our newest globes are calculated for the year 1800.

2. On the 20th of August 1805, the moon's right astension was 91° 3', and her declination 24° 48′; find her place on the globe at that time.

Answer. In the milky way, a little above the left foot of Castor,

3. What stars have the following right ascensions and declinations?

Right Ascensions Declinations. Right Ascensions. Declinations.

7° 19'

55° 26' N.

830 6'

34° 11' S.

8

27 S. 129 2

7 8 N.

76 14 4. On the first of December 1810, the moon's right ascension was 320° 28', and her declination 11° 45′ S.; find her place on the globe.

5. On the first May 1805, the declination of Venus was 11° 41' N., and her right ascension 31° 30'; find her place on the globe.

6. On the 19th of January 1805, the declination of Jupiter was 19° 29′ south, and his right ascension 238°; find his place on the globe.

PROBLEM LXVIII.

The latitude and longitude of the moon, a star, or a planet, given, to find its place on the globe.

Rule. Place the division of the quadrant of altitude marked o, on the given longitude in the ecliptic, and the upper end on the pole of the ecliptic; then under the given latitude, on the graduated edge of the quadrant, you will find the star, or place of the moon, or planet.

Examples. 1. What star has O signs 6° 16′ of longitude, and 12° 36′ N. latitude?

Answer. y in Pegasus.

2. On the 5th of June 1810, at midnight, the moon's longitude was 3s. 26° 32', and her latitude 4° 55' S.; find her place on the globe.

3. What stars have the following latitudes and longi. tudes?

2 25 51 21 6 S.

11 O 56

16 3 S.

4. On the first of June 1810, the longitudes and latitudes of the planets were as follow; required their

places on the globe?

Long todes

Latitudes

Longitudes.

Latitudes. 0° 56' S.

The day and hour, and the latitude of a place being given, to find what stars are rising, setting, culminating, &c. Rule. Elevate the pole to the latitude of the place, find the sun's place in the ecliptic, bring it to the brass meridian, and set the index of the hour circle to 12; then, if the time be before noon, turn the globe eastward on its axis till the index has passed over as many hours as the time wants of noon; but, if the time be past noon, turn the globe westward till the index has passed over as many hours as the time is past noon: then all the stars on the eastern semi-circle of the horizon will be rising, those on the western semi-circle will be setting, those under the brass meridian above the horizon will be culminating, those above the horizon will be visible at the given time and place, those below will be invisible. If the globe be turned on its axis from east to west, those stars which do not go below the horizon never set at the given place; and those which do not come above the horizon never rise; or, if the given latitude be subtracted from 90 degrees, and circles be described on the globe, parallel to the equinoctial, at a distance from it equal to the degrees in the remainder, they will be the circles of perpetual apparition and occultation.

Examples. 1. On the 9th of February, when it is nine o'clock in the evening at London, what stars are rising,

what stars are setting, and what stars are on the meridian.

Answer. Alphacca in the northern Crown is rising; Arcturus and Mirach in Bootes just above the horizon; Sirius on the meridian ; Procyon and Castor and Pollux a little east of the meridian. The constellations Orion, Taurus, and Auriga, a little west of the meridian; Markab, in Pegasus, just below the western edge of the horizon, &c.

2. On the 20th of January, at two o'clock in the morning at London, what stars are rising, what stars are setting, and what stars are on the meridian?

Answer. Vega in Lyra, the head of the Serpent, Spica, Virginis, &c. are rising; the head of the great Bear, the claws of Cancer, &c. on the meridian; the head of Andromeda, the neck of Cetus, and the body of Columba Noachi, &c. are setting.

3. At ten o'clock in the evening at Edinburgh, on the 15th of November, what stars are rising, what stars are setting, and what stars are on the meridian?

4. What stars do not set in the latitude of London, and at what distance from the equinoctial is the circle of perpetual apparition?

5. What stars do not rise to the inhabitants of Edinburgh, and at what distance from the equinoctial is the circle of perpetual occultation?

6. What stars never rise at Otaheite, and what stars never set at Jamaica?

7. How far must a person travel southward from London to lose sight of the Great Bear?

8. What stars are continually above the horizon at the north pole, and what stars are constantly below the horizon thereof?

PROBLEM LXX.

The latitude of a place, day of the month, and hour being given, to place the globe in such a manner as to represent the heavens at that time; in order to find out the relative situations and names of the constellations and remarkable stars.

Rule. Take the globe out into the open air, on a clear star-light night, where the surrounding horizon is uninterrupted by different objects; elevate the sole to the latitude of the place, and set the globe due north and south by a meridian line, or by a mariner's compass,

taking care to make a proper allowance for the variation; find the sun's place in the ecliptic, bring it to the brass meridian, and set the index of the hour circle to 12; then, if the time be after noon, turn the globe westward on its axis till the index has passed over as many hours as the time is past noon; but, if the time be be fore noon, turn the globe eastward till the index has passed over as many hours as the time wants of noon: fix the globe in this position, then the flat end of a pencil being placed on any star on the globe, so as to point towards the centre, the other end will point to that particular star in the heavens.

PROBLEM LXXI.

To find when any star, or planet, will rise, come to the meridian, and set at any given place.

Rule. Elevate the pole so many degrees above the horizon as are equal to the latitude of the place; find the sun's place in the ecliptic, bring it to the brass meridian, and set the index of the hour circle to 12; bring the the star (or the planet's place*) to the eastern part of the horizon, and the hours between the sun's place and the brass meridian will be the time from noon when the star or planet rises. If the sun's place be to the east of the brass meridian, the star or planet will rise before noon; if the sun's place be to the west of the brass meridian, the star or planet will rise after noon. In a similar manner, by bringing the star or planet to the meridian, and western part of the horizon, you will have the times of its culminating and setting.

Examples. 1. At what time will Arcturus rise, come to the meridian, and set at London, on the 7th of September?

*The latitude and longitude (or the right ascension and declinaion) of the planet, must be taken from an ephemeris, and its place on the globe must be determined by Prob. LXVIII (or LXVII).