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HISTORICAL VIEW OP THE

sioned not only regret, but even offence, in the state ofVenice , who had patronised him there. In all otherplaces he was received with marks of the highest estima-tion. Going to Rome in l6ll, all ranks vied in payinghim attention ; and evinced the greatest anxiety to wit-ness the facts he had observed. In 1612, on his returnto Florence, he published his discourse on floating bodies,in which he explains the principles of that part of hy-drostatics with great accuracy ; noticing, among otherpoints, the remarkable experiment called the hydrostaticparadox.

In December, 1612, Galileo was much perplexed bythe disappearance of the lateral appendages he had beforenoticed in the planet Saturn : but no adequate theoryseems to have suggested itself of their true nature.

In ]6l5, we find him entering warmly into variousschemes, then under the consideration of the Spanish government, for the discovery of the longitude ; and, inparticular, suggesting the use of the eclipses of Jupiter ’ssatellites for the purpose.

The year 1618 was remarkable for the appearance ofthree comets: these gave occasion to much discussion,in which Galileo , at least, displays his caution in observ-ing that the distance of these bodies cannot be accuratelydetermined from their parallax. He, probably, stillinclined to the notion of their being only a species ofmeteors.

Galileo’s telescope was composed of a convex objectglass and a concave eye glass,—precisely the same con-struction as that now adopted for the common opera glass.Kepler, in his “ Dioptrics,” had investigated the moregeneral theory of the combinations of lenses, adjustedwith the principal foci in coincidence, and so (in theory)forming telescopes ; and among them had treated ofthe case when both lenses are convex, and are placedat a distance equal to the sum of their focal lengths,giving an inverted image. This is the constructioncalled the astronomical telescope. But none of thiskind were made till Scheiner took up the invention and