Page:Gods Glory in the Heavens.djvu/114

96 the observed perturbation, so that it is likely other planets will yet be discovered on the sun's disc.

The black spot, produced by a planet coming between us and the sun, can readily be distinguished from the dark spots on the sun itself, which can often be seen by the naked eye. The planet's motion is much more rapid. Vulcan's time of passage was only 1 hour 17 minutes. As the sun takes twenty-five days to rotate on his axis, the solar spots are seen usually for days together before they disappear. The planetary spot is perfectly round and sharp; the solar, is usually of an irregular form, and shaded. The planetary spot does not change its form in passing across the disc; it is otherwise with the solar spots. In the case of the latter, the black central spot is the bottom of a deep pit, and the shaded parts are the shelving sides. When the spot is in the centre of the disc, you are looking straight down, and if it is circular you see it perfectly round; but when it moves to the side, the circle, from the change of perspective, becomes an oval. Solar spots are usually near the equator of the sun; planets may be seen at any distance from it. Besides these, there are other points of difference which render it impossible to mistake a solar spot for a planet.

The last news from Paris, is that the medical practitioners, there, have been attempting to spoil their unassuming brother, who has been thus suddenly raised to distinction. They invited him to a grand