OF THE PHENOMENA OF THE HEAVENS, AS SEEN FROM THE EARTH, THE HE various appearances of the celestial bodies, as seen from the earth, are the facts which lay the foundation of all astronomical knowledge. To account for, and explain them, is it's principal business: a true idea of these phænomena is therefore a neceffary step to a knowledge of aftronomy. OF THE APPARENT MOTION OF THE SUN. The first and most obvious phænomenon is the daily rifing of the fun in the east, and his fetting in the weft; after which the moon and ftars appear, ftill keeping the fame wefterly courfe, till we lofe fight of them altogether. This cannot be long obferved, before we must also perceive, that neither the fun nor moon always rife exactly at the fame point of the heavens. If we commence our obfervations of the fun, for instance, in the beginning of March, we fhall find him appear to rife more to the northward every day, to continue longer above the horizon, to be more vertical, or higher, at mid-day; this continues till towards the end of June, when he moves backward in the fame manner, and continues this retrograde motion. till near the end of December, when it begins to move forwards, and so on. It is this change in the fun's place, that occafions him to rife and fet in different parts of the horizon, at different times of the year. It is from hence that his height is fo much greater in fummer, than in winter. In a word, the change of the fun's place in the heavens is the cause of the different length in the days and nights, and the viciffitudes of the feafons. As the knowledge of the fun's apparent motion is of great importance, and a proper conception of it abfolutely neceffary, in order to form a true idea of the phænomena of the heavens, the reader will excufe my dwelling fomething longer upon it. If on an evening we take notice of fome fixed star near the place where the sun sets, and observe it for several fucceffive evenings, we shall find that it approaches the fun from day to day, till at laft it will disappear, being effaced by his light, though but a few days before it was at a fufficient distance from him. That it is the fun which approaches the stars, and not the ftars the fun, is plain, for this reafon; the stars always rise and set every day at the same points of the horizon, opposite to the fame terrestrial objects, and are always at the fame distance from each other; whereas the fun is continually changing both the place of it's rifing and fetting, and it's distance from the stars. The fun advances nearly one degree every day, moving from west to east; so that in 365 days we see the same star near the setting fun, as was obferved to be near him on the fame day in the preceding year. In other words, the fun has returned to the place from whence he fet out, or made what we call his annual revolution. We cannot indeed obferve the fun's motion among the fixed stars immediately, on account of the brightness of his light, which prevents our seeing those stars that are in his neighbourhood ; but |