270 GEOGRAPHY AND ASTRONOMY. The hour of the sun is its distance from noon or the meri- dian of the place measured on the equator by 15 degrees, for 'every 15 degrees on the equator make an hour. Or it may be reckoned from the opposite meridian or midnight. Note, The right ascension is reckoned either in degrees or in hours. 'rho latitude of a star or planet is its distance northward or southward from the ecliptic : Note, The sun has no latitude be- cause it is always in the ecliptic. The longitude of the sun or star is its distance from the point aries eastward measured on the ecliptic. But with regard to the sun or a planet, this is usually called the place of the sun, or planet, for any particular day, i. e. its place in the Zodiac, or the degreeof the sign in which it is at that time. The altitude or height of the sun or a star is its distance from and above the horizon, measured on the quadrant of alti- tudes. The depression of the sun or star is its distance from and below the horizon, The azimuth of the sun or a star is its dis- stance from the cardinal points of east, west, north or south, measured on the horizon. The sun or star's meridian altitude is its altitudeor height when it is on the meridian or at the south. The vertical altitude of the sun is used by some writers for its height above the horizon when it is in the azimuth or vertical circle of east or west. But the sun is. said to be vertical at any place when it is in the zenith of that place at noon. The amplitude of the sun or a star is its azimuth or distance from east or west at rising or setting. The ascensional difference is the time of the sun or star's risingor setting before or after six o'clock : Or it is the difference between the sun or star's semidiurnal arc and a quadrant or 90 degrees, as some persons express it, because 90 degrees or a quadrant reaches from 6 o'clock to 12. PROBLEMS. ProblemL " To find the longitude and latitude of any place on the earthly globe." Turn the globe about till the place come just under the side of the brazen meridian ou which the figures are, which iscalled its graduated edge, then the degree marked on the meridian just over the place shews the latitude either north or south : And the globe so standing, that degree of the equator, which is cut by the meridian shows the true longitude of the place. So London will appear to have 511 degrees of north latitude, and near 18 de- grees of longitude, counting the first meridian at Teneriff. So Romehas 411 degrees of north latitude, and about 13 degrees of , longitude, eastward from London, or almost 31 degrees front Teueriff.
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