Next November, Newton redeemed his promise to Halley by sending him, by the hand of Mr. Paget, a fellow of Trinity College and mathematical master of Christ's Hospital, a copy of his demonstration; and very soon afterward Halley again visited Cambridge to confer with Newton about the problem. On his return to London on 10 December 1684, he informed the Royal Society "that he had lately seen Mr. Newton at Cambridge, who had shown him a curious treatise "De Motu"", which at Halley's desire he promised to send to the Society to be entered upon their register. "Mr. Halley was desired to put Mr. Newton in mind of his promise for the securing this invention to himself, till he could be at leisure to publish it", and Paget was desired to join with Halley in urging Newton to do so. By the middle of February Newton had sent his paper to Aston, one of the secretaries of the Society, and in a letter to Aston dated 23 February 1685, Newton thanked him for "having entered on the register his notions about motion". This treatise "De Motu" was the starting point of the "Principia", and was meant to be a short account of what that work was intended to embrace. It occupies twenty-four octavo pages, and consists of four theorems and seven problems, some of which are identical with some of the most important propositions of the second and third sections of the first book of the " Principia".