The most important of the optical discoveries of Newton, of which we have given a general history, were communicated to the Royal Society in detached papers; but the disputes in which they had involved their author made him hesitate about the publication of his other discoveries. Although he had drawn up a connected view of his labours under the title of “Opticks, or a Treatise on the Reflexions, Refractions, Inflexions, and Colours of Light,” yet he resolved not to publish this work during the life of Hooke, by whose rival jealousy his tranquillity had been so frequently interrupted. Hooke, however, died in 1702, and the Optics of Newton appeared in English in 1704. Dr. Samuel Clark proposed a Latin edition of it, which appeared in 1706, and he was generously presented by Sir Isaac with 500_l._ (or 100_l._ for each of his five children), as a token of the approbation and gratitude of the author. Both the English and the Latin editions have been frequently reprinted both in England and on the Continent,[33] and there perhaps never was a work of profound science so widely circulated. CHAPTER X. _Astronomical Discoveries of Newton—Necessity of combined Exertion to the Completion of great Discoveries—Sketch of the History of Astronomy previous to the Time of Newton—Copernicus, 1473–1543— Tycho Brahe, 1546–1601—Kepler, 1571–1631—Galileo, 1564–1642._ From the optical labours of Newton we now proceed to the history of his astronomical discoveries—those transcendent deductions of human reason by which he has secured to himself an immortal name, and vindicated the intellectual dignity of his species. Pre-eminent as his triumphs have been, it would be unjust to affirm that they were achieved by his single arm. The torch of many a preceding age had thrown its light into the strongholds of the material universe, and the grasp of many a powerful hand had pulled down the most impregnable of its defences. An alliance, indeed, of many kindred spirits had been long struggling in this great cause, and Newton was but the leader of their mighty phalanx,—the director of their combined genius,—the general who won the victory, and therefore wears its laurels.