As a rule it is almost impossible to fix the dates of the "Epistolæ Ho-Elianæ," but the first part of "Dodona's Grove" was issued in 1640, and the second part in 1650, so that the letter was probably written in 1651. Even if the letters were never really sent to those to whom they are addressed, Howell selected his apparent correspondents with such care that he would not have addressed Harvey in this manner unless he had been credited with some skill as a critic of general literature. This, too, is borne out in another letter to Nardi on October 25, 1655, in which he says that he is used to solace his declining years and to refresh his understanding, jaded with the trifles of everyday life, by reading the best works. Shortly before he died he was engaged in reading Oughtred's "Clavis Mathematica," and in working out the problems. The book was no doubt brought under his notice by Charles Scarborough, who with Seth Ward was the first to read it with his pupils at Cambridge, where it long remained a favourite textbook. When Scarborough and Ward were young, they once made a journey to see Oughtred, an old Etonian, "who was then living at Albury, in Surrey, to be informed of many things in his 'Clavis Mathematica,' which seemed at that time very obscure to them. Mr. Oughtred treated them with great humanity, being very much pleased to see such ingenious young men," says Anthony Wood, who tells the story, "apply themselves to those studies, and in a short time he sent them away well satisfied in their desires." Harvey still retained his Lumleian lectureship, the duties of which he conscientiously discharged to the last. His life, says Dr. Munk, already prolonged beyond the span allotted to man, and his waning powers yet further broken by repeated and severe attacks of illness, warned him of his approaching end. He had lived to see his grand discovery of the circulation of the blood universally accepted and inculcated as a canon in most of the medical schools of Europe; and he is said by Hobbes to have been "the only one that conquered envy in his lifetime and saw his new doctrine everywhere established." Harvey now prepared for the great change awaiting him, and on July 28, 1656, resigned his lectureship, took his leave of the College, and in so doing manifested the same zeal for its prosperity as had marked the whole of his former life. On this occasion he put the crowning act to his munificence by giving to the College in perpetuity his patrimonial estate at Burmarsh in Kent, then valued at £56 a year. The particular purposes of this donation were the institution of an annual feast, at which a Latin oration should be spoken in commemoration of the benefactors of the College, a gratuity for the orator, and a provision for the keeper of his library and museum. All this attention to perpetuate a spirit of concord and social friendship among his brethren, was in full accordance with Harvey's benevolent and liberal sentiments.