The use of telescopes opened, in a manner, a new world to Galileo. He observed with astonishment the increased magnitude and splendour of the planets and their satellites, formerly invisible: which afforded additional proofs of the veracity of the Copernican system, particularly the satellites of Jupiter, and the phasis of Venus. He discovered an innumerable multitude of fixed stars, which the naked eye could not discern, and what greatly excited his wonder, without the least increase in their size or brightness.
About the same time, John Napier, of Merchiston, in Scotland, invented what are called “Logarithms,” first published at Edinburgh in 1614, afterwards improved by Mr. Briggs, Professor of Geometry, at Oxford, in which, by a very ingenious contrivance, addition is made to answer for multiplication, and subtraction for division; an invention of the greatest utility in astronomical calculations.
Galileo was not afflicted with poverty, but with persecution. At seventy years of age he was called before the Holy Inquisition, for supporting opinions contrary to Scripture,—and was obliged, on the 11th of June, 1633, formally to abjure them, to avoid being burnt as a heretic. The system of Copernicus had yet gained but few converts; and the bulk of professions and learned men in Europe, attached to the philosophy of Aristotle, supported the old doctrine. Galileo was condemned to prison, and confined to the small city of Arcem, with its territory, where he consoled himself by the study of astronomy. He contrived a method of discovering the longitude by the satellites of Jupiter, which, however, has not been productive of all the advantages he expected. He died in prison, or rather in exile, in 1642.
Although there were a great number of astronomers contemporary with Kepler and Galileo, none made any conspicuous figure. John Bayer, of Augsburg, introduced the Jewish method of marking the stars with letters of the Greek and Latin alphabets; this the Jews use because their law does not permit the use of figures, the produce of fancy.
In 1732, astronomers were very attentive to observe the transit of Venus over the disc of the sun, which Kepler had predicted, as a confirmation of the system of Copernicus. Mercury was observed by Gassendi in France, and some others; but the transit of Venus did not then take place for their inspection.
The transit of Venus was first seen by Jeremiah Horrox, of Hoole, an obscure village, fifteen miles north of Liverpool, on the 24th of November, 1639, and at the same time by his friend, William Crabtree, at Manchester. Horrox was born in 1619, and died in 1641, in the twenty-third year of his age. He wrote an account of his observations, which were published after his death, under the title of “Venus in Sole visa,” by Hevelius.
The Copernican system was first publicly defended in England, by Dr. Wilkins, in 1660; in France, by Gassendi, the son of a peasant in Provence, who published many valuable works on Philosophy. He was born in 1592, and died in 1655. He was violently opposed by Morin, a famous astrologer.
Descartes, descended from a noble family, the son of a counsellor of Brittany, in France, born at Haye, in Tourraine, 31st of March, 1596, early distinguished himself by his knowledge in algebra and geometry. He attacked and overturned the philosophy of Aristotle, in his own country. He attempted to establish certain principles, which, though founded in theory, he took for granted, by which he accounted for all appearances. Like Mochus and Democritus, he imagined all space to be filled with corpuscules, or atoms, in continual agitation, and denied the possibility of a vacuum. He explained everything by supposing vortices, or motions round a centre, according to the opinions of Democritus, and thus discovered the centrifugal force in the circular motion of the planets. But the system of Descartes not being founded on facts or experiments, did not subsist long: although at first it had many followers. His astronomical opinions were much the same with those of Copernicus.
Although the lively notions of Descartes led him into error, yet his exalted views greatly contributed to the improvement of science. Men were led to observation and experiments, in order to overturn his system, and astronomy was cultivated by persons of ability; viz., Bouillard, at Paris; Ward, at Oxford, 1653; and by Helvelius, at Dantzic, 1643, who constructed a fine observatory, and collected a great many facts by his long assiduous observation, for fifty years, during which he made many discoveries concerning the planets, fixed stars, and particularly comets. Colbert, in the name of Louis XIV., sent him a sum of money and a pension. Hevelius published a catalogue of fixed stars, entitled, “Firmamentum Sobieskianum,” dedicated to John Sobieski, King of Poland, at that time justly famous for having raised the siege of Vienna, when attacked by the Turks, 1683. In honour of whom Helvelius formed a new constellation between Antinonus and Serpenterius, called Sobieski’s Shield.
But the most distinguished astronomer of that time was Christian Huygens, son to the secretary of the Prince of Orange, born at the Hague, 14th of April, 1629, and educated at Leyden, under Schooten, the commentator on Descartes,—famous for the application of pendulums to clocks and springs to watches, for the improvement of telescopes and microscopes, and for the great discoveries he made, in consequence of these improvements in astronomy.