All these planets, like the signs of the zodiac, are indicated by astronomers by certain symbols, which, as they derive their form from the names or nature of the planets, may properly here be explained. The sign of Neptune is ♆, representing the trident of the sea; for Uranus ♅, which is the first letter of Herschel with a little globe below; ♄ is the sickle of time, or Saturn; ♃ is the representation of the first letter of Zeus or Jupiter; ♂ is the lance and buckler of Mars; ♀ the mirror of Venus; ☿ the wand of Mercury; ☉ the sun's disc; and ☽ the crescent of the moon.
Plate IX.—The Solar System.
The more modern discoveries have, of course, been all made by means of the telescope, and a few words on the history of its discovery may fitly close this chapter.
According to Olbers, a concave and convex lens were first used in combination, to render objects less distant in appearance, in the year 1606. In that year the children of one Jean Lippershey, an optician of Middelburg, in Zealand, were playing with his lenses, and happened to hold one before the other to look at a distant clock. Their great surprise in seeing how near it seemed attracted their father's attention, and he made several experiments with them, at last fixing them as in the modern telescope—in draw tubes. On the 2nd of October, 1606, he made a petition to the States-General of Holland for a patent. The aldermen, however, saw no advantage in it, as you could only look with one eye instead of two. They refused the patent, and though the discovery was soon found of value, Lippershey reaped no benefit.
Galileo was the first to apply the telescope to astronomical observations. He did not have it made in Holland, but constructed it himself on Lippershey's principle. This was in 1609. Its magnifying power was at first 4, and he afterwards increased it to 7, and then to 30. With this he discovered the phases of Venus, the spots on the sun, the four satellites of Jupiter, and the mountains of the moon.
Plate X.—The Discovery of the Telescope.