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KEPLER'S CONTINUATION.
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different from the first account, something changed in course of time.[1]
At the end of his letter Galileo seemed to think that he had come to the end of his reports about the planets, and observations of new phenomena respecting them, but ever on the watch, that eye of his, that one not of Nature's making—I mean his telescope—in a short time made more discoveries, concerning which read the following letter of Galileo:—
Account of Galileo's discovery of the phases of Venus."Di Firenze li 11 di Decembre 1610.—Sto con desiderio, attendendo la risposta a due mie scritte ultimamente per sentire quello, che averà detto il Sig.- ↑ The completion of Galileo's observations on Saturn depended on the improvement of astronomical instruments, as will be evident from the following sketch. Galileo made out the first indications of Saturn's ring in 1610, as narrated in his letter, with a power of thirty; but in December 1612 he wrote to one of his friends, Marco Velseri, that he could no longer see these indications, and began to imagine that his telescope had deceived him, and apparently abandoned farther researches. Hevelius in 1642 saw the ring more clearly, but figured it as two crescents attached to Saturn by their cusps. At length, in 1653, Huyghens provided himself with a power of one hundred, having made the lenses with his own hands, and immediately discovered the explanation of the phenomena which had baffled previous observers. He published his explanation of Saturn's ring, and his discovery of the first satellite, in his Systema Saturnium, 1659. Cassini, with still more powerful instruments, discovered four more satellites in 1671, 1672, 1684. Sir William Herschel in 1789 detected two more, "which can only be seen with telescopes of extraordinary power and perfection, and under the most favourable atmospheric circumstances."—(Herschel, Outlines of Astronomy, § 548.) And the last of the eight satellites was discovered in 1848 by Lassell of Liverpool, and Bond of Cambridge, U.S., simultaneously.
