His next attempt was almanac-making, in the which he improved considerably upon those current at the time. His almanac for 1670 was rejected, however, and returned to him, and, not to lose his whole labour, he sent his calculations of an eclipse of the sun, and of five occultations of stars by the moon, which he had undertaken for the almanac, to the Royal Society. He sent the paper anonymously, or, rather, signed it with an anagram, 'In mathesi a sole fundes,' for 'Johannes Flamsteedius.' His covering letter ends thus:-- 'Excuse, I pray you, this juvenile heat for the concerns of science and want of better language, from one who, from the sixteenth year of his age to this instant, hath only served one bare apprenticeship in these arts, under the discouragement of friends, the want of health, and all other instructors except his better genius.' This letter was dated November 4, 1669, and on January 14, Mr. Oldenburg, the secretary of the Society, replied to him in a letter which the young man cannot but have felt encouraging and flattering to the highest degree. 'Though you did what you could to hide your name from us,' he writes, 'yet your ingenious and useful labours for the advancement of Astronomy addressed to the noble President of the Royal Society, and some others of that illustrious body, did soon discover you to us, upon our solicitous inquiries after their worthy author.' And after congratulating him upon his skill, and encouraging him to furnish further similar papers, he signs himself, 'Your very affectionate friend and real servant'--no unmeaning phrase, for the friendship then commenced ceased only with Oldenburg's life. The following June, his father, pleased with the notice that some of the leading scientific men of the day were taking of his son, sent him up to London, that he might be personally acquainted with them; and he then was introduced to Sir Jonas Moore, the Surveyor of the Ordnance, who made him a present of Townley's micrometer, and promised to furnish him with object-glasses for telescopes at moderate rates. On his return journey he called at Cambridge, where he visited Dr. Barrow and Newton, and entered his name in Jesus College. It was not until the following year, 1671, that he was enabled to complete his own observatory, as he had had to wait long for the lenses which Sir Jonas Moore and Collins had promised to procure for him. He still laboured under several difficulties, in that he had no good means for measuring time, pendulum clocks not then being common. He, therefore, with a practical good sense which was characteristic, refrained from attempting anything which lay out of his power to do well, and he devoted himself to such observations as did not require any very accurate knowledge of the time. At the same time, he was careful to ascertain the time of his observations as closely as possible, by taking the altitudes of the stars.