On February 25th Mr. Aston, the secretary, communicated a letter from Newton in which he expressed his willingness "to enter in the register his notions about motion, and his intentions to fit them suddenly for the press." The progress of his work was, however, interrupted by a visit of five or six weeks which he made in Lincolnshire; but he proceeded with such diligence on his return that he was able to transmit the manuscript to London before the end of April. This manuscript, entitled _Philosophic Naturalis Principia Mathematics_ and dedicated to the society, was presented by Dr. Vincent on April 28, 1686, when Sir John Hoskins, the vice-president and the particular friend of Dr. Hooke, was in the chair. Dr. Vincent passed a just encomium on the novelty and dignity of the subject; and another member added that "Mr. Newton had carried the thing so far that there was no more to be added." To these remarks the vice-president replied that the method "was so much the more to be prized as it was both invented and perfected at the same time." Dr. Hooke took offence at these remarks, and blamed Sir John for not having mentioned "what he had discovered to him"; but the vice-president did not seem to recollect any such communication, and the consequence of this discussion was that "these two, who till then were the most inseparable cronies, have since scarcely seen one another, and are utterly fallen out." After the breaking up of the meeting, the society adjourned to the coffee house, where Dr. Hooke stated that he not only had made the same discovery, but had given the first hint of it to Newton. An account of these proceedings was communicated to Newton through two different channels. In a letter dated May 22d Dr. Halley wrote to him "that Mr. Hooke has some pretensions upon the invention of the rule of the decrease of gravity being reciprocally as the squares of the distances from the centre. He says you had the notion from him, though he owns the demonstration of the curves generated thereby to be wholly your own. How much of this is so you know best, as likewise what you have to do in this matter; only Mr. Hooke seems to expect you would make some mention of him in the preface, which it is possible you may see reason to prefix."