SECTION VI. 235 of right ascension on the equator, though the sunor stars may be far from the equator. By these you may also compute on the earthly globe what hour it is at any place in the world, by having the true hour given at any other place, and by changing the degrees of their difirèrence of longitude into hours. But singe several questions or problems that relate to the hour, cannot be so commodiously resolved by these few meridians or hour-lines, because every place on the earth bath its proper meridian where the sun is at 12 o'clock, therefore there is a brass dial-plate fixed at the north-pole in the globe, whose 24 hours do exactly answer the 24 hour circles which might be drawn on the globe: now the dial being fixed, and the pointer being moveable, this answers all the purposes of having an infinite number of hour circles drawn on the globe, and fitted to every spot on the heavens or the earth. For the pointer or index may be set to 12 o'clock, when the sun's true place in the heavens, or when any place on the earth is brought to the brass meridian, and thus the globe moving round with the index naturally repre- sents, and shews by the dial-plate the 24 hours of any day in the year, or in any particular town or city. Note, The upper 12 a clock is the hour of noon, the- lower 12 is the midnight hour, when the globe is fixed for any particular latitude where there are days and nights. The declination of the sun or stars is their distancefrom the equator toward the north or south pole, measured on the meridian; and it is the same thing with latitude on the earthly globe. Note, the sun in the vernal or autumnal equinoxes, and the stars that are just on the equator have uo declination. Parallels ofdeclination are lines parallel to the equator, the same as the parallels of latitude on the earthlyglobe. In the heavens they may be supposed to be drawn through each degree of the meridian, and thus shew the declination of all the stars ; or theymay be drawn through every degree of the ecliptic, and ,thus represent the sun's path, every day in the year. These parallel lines also would lead the eye to the degree of the sun's or 'any particular star's declination marked on the meridian. The declination is called north or south declination accord- ing as the sun or stars lies, northward or southward from the equator. Observe here, -that as any place, town, or city on earth is found determined by the parallel of its latitude; crossing its line of 'longitude ; so the proper place of the sun or star in the heavens is.found.and determinedby the point where its parallel of declination crosses its meridian or line of right ascension;
RkJQdWJsaXNoZXIy OTcyMjk=