These assurances were no doubt founded on the belief that Galileo would adhere to his pledges; but so bold and inconsiderate was he in the expression of his opinions, that even in Rome he was continually engaged in controversial discussions. The following very interesting account of these disputes is given by Querenghi, in a letter to the Cardinal D'Este:-- "Your eminence would be delighted with Galileo if you heard him holding forth, as he often does, in the midst of fifteen or twenty, all violently attacking him, sometimes in one house, sometimes in another. But he is armed after such fashion that he laughs all of them to scorn; and even if the novelty of his opinions prevents entire persuasion, he at least convicts of emptiness most of the arguments with which his adversaries endeavour to overwhelm him. He was particularly admirable on Monday last in the house of Signor Frederico Ghisilieri; and what especially pleased me was, that before replying to the contrary arguments, he amplified and enforced them with new grounds of great plausibility, so as to leave his adversaries in a more ridiculous plight, when he afterwards overturned them all." The discovery of Jupiter's satellites suggested to Galileo a new method of finding the longitude at sea. Philip III. had encouraged astronomers to direct their attention to this problem, by offering a reward for its solution; and in those days, when new discoveries in science were sometimes rejected as injurious to mankind, it was no common event to see a powerful sovereign courting the assistance of astronomers in promoting the commercial interests of his empire. Galileo seems to have regarded the solution of this problem as an object worthy of his ambition; and he no doubt anticipated the triumph which he would obtain over his enemies, if the Medicean stars, which they had treated with such contempt, could be made subservient to the great interests of mankind. During his residence at Rome in 1615 and 1616, Galileo had communicated his views on this subject to the Comte di Lemos, the Viceroy of Naples, who had presided over the council of the Spanish Indies. This nobleman advised him to apply to the Spanish minister the Duke of Lerma; and, through the influence of the Grand Duke Cosmo, his ambassador at the court of Madrid was engaged to manage the affair. The anxiety of Galileo on this subject was singularly great. He assured the Tuscan ambassador that, in order to accomplish this object, "he was ready to leave all his comforts, his country, his friends, and his family, to cross over into Spain, and to stay as long as he might be wanted at Seville or at Lisbon, or wherever it might be convenient to communicate a knowledge of his method." The lethargy of the Spanish court seems to have increased with the enthusiasm of Galileo; and though the negotiations were occasionally revived for ten or twelve years, yet no steps were taken to bring them to a close. This strange