Although Galileo had been thwarted in his attempt to introduce into the Spanish marine his new method of finding the longitude at sea, yet he never lost sight of an object to which he attached the highest importance. As the formation of correct tables of the motion of Jupiter's satellites was a necessary preliminary to its introduction, he had occupied himself for twenty-four years in observations for this purpose, and he had made considerable progress in this laborious task. After the publication of his "Dialogues on Motion," in 1636, he renewed his attempts to bring his method into actual use. For this purpose he addressed himself to Lorenzo Real, who had been the Dutch governor-general in India, and offered the free use of his method to the states-general of Holland.[31] The Dutch government received this proposal with an anxious desire to have it carried into effect. At the instigation of Constantine Huygens, the father of the illustrious Huygens, and the secretary to the prince of Orange, they appointed commissioners to communicate with Galileo; and while they transmitted him a gold chain as a mark of their esteem, they at the same time assured him, that if his plan should prove successful it should not pass unrewarded. The commissioners entered into an active correspondence with Galileo, and had even appointed one of their number to communicate personally with him in Italy. Lest this, however, should excite the jealousy of the court of Rome, Galileo objected to the arrangement, so that the negotiation was carried on solely by correspondence.
It was at this time that Galileo was struck with blindness. His friend and pupil, Renieri, undertook, in this emergency, to arrange and complete his observations and calculations; but before he had made much progress in the arduous task, each of the four commissioners died in succession, and it was with great difficulty that Constantine Huygens succeeded in renewing the scheme. It was again obstructed, however, by the death of Galileo; and when Renieri was about to publish, by the order of the grand duke, the "Ephemeris," and "Tables of the Jovian Planets," he was attacked with a mortal disease, and the manuscripts of Galileo, which he was on the eve of publishing, were never more heard of. By such a series of misfortunes were the plans of Galileo and of the states-general completely overthrown. It is some consolation, however, to know that neither science nor navigation suffered any severe loss. Notwithstanding the perfection of our present tables of Jupiter's satellites, and of the astronomical instruments by which their eclipses may be observed, the method of Galileo is still impracticable at sea.