An Epitome of Astronomy with the New Discoveries
Including an Account of the Eidouranion, or Transparent Orrery
9781465647245
281 pages
Library of Alexandria
Overview
As information is the primary object of this lecture, it is thought more useful to exhibit parts of the solar system, separately, before a grand display was made of the whole. This scene therefore, opens with only the Sun and the Earth. The Sun seems suspended in the middle of the system, and by spots on his face, is seen to turn round on his axis in 25¼ days; light issues from his orb in all directions; in the blaze of which is suspended the Earth, turning on its axis to produce day and night, and revolving round the Sun to produce the seasons: its axis inclines 23½ degrees from a perpendicular to the plane of its orbit; and by that axis keeping parallel to itself during this annual journey, the northern and southern hemispheres are alternately addressed to the Sun; shewing, when it is summer in one, it is winter in the other, and vice versâ. This scene so naturally exhibits the cause of day, night, twilight, summer and winter, spring and autumn, long and short days, &c. that a bare inspection of the Machine is sufficient to convey the clearest idea of these phænomena. The Earth in this scene ought to be unshackled with meridians or parallels of latitude:—to be a free and independent ball, with land and water represented as they would appear to a distant spectator looking at the real Earth. But as globes are seldom seen without these appendages, a globe of two feet in diameter, equipped with meridians and parallels of latitude (being requisite for illustration) will perform a diurnal and annual motion round the Sun, and explain the above phænomena on so large a scale, that their effects on the smallest island may be seen from the most distant part of the theatre.
