_It will perhaps be expected, that I should say something particular of a person, to whom I must always acknowledge my self to be much obliged. What I have to declare on this head will be but short; for it was in the very last years of Sir_ ~ISAAC~_’s life, that I had the honour of his acquaintance. This happened on the following occasion. Mr._ Polenus, _a Professor in the University of_ Padua, _from a new experiment of his, thought the common opinion about the force of moving bodies was overturned, and the truth of Mr._ Libnitz_’s notion in that matter fully proved. The contrary of what Polenus had asserted I demonstrated in a paper, which Dr._ ~MEAD~, _who takes all opportunities of obliging his friends, was pleased to shew Sir_ ~ISAAC NEWTON~ _This was so well approved of by him, that he did me the honour to become a fellow-writer with me, by annexing to what I had written, a demonstration of his own drawn from another consideration. When I printed my discourse in the philosophical transactions, I put what Sir_ ~ISAAC~ _had written in a scholium by it self, that I might not seem to usurp what did not belong to me. But I concealed his name, not being then sufficiently acquainted with him to ask whether he was willing I might make use of it or not. In a little time after he engaged me to take care of the new edition he was about making if his Principia. This obliged me to be very frequently with him, and as he lived at some distance from me, a great number of letters passed between us on this account. When I had the honour of his conversation, I endeavoured to learn his thoughts upon mathematical subjects, and something historical concerning his inventions, that I had not been before acquainted with. I found, he had read fewer of the modern mathematicians, than one could have expected; but his own prodigious invention readily supplied him with what he might have an occasion for in the pursuit of any subject he undertook. I have often heard him censure the handling geometrical subjects by algebraic calculations; and his book of Algebra he called by the name of Universal Arithmetic, in opposition to the injudicious title of Geometry, which_ Des Cartes _had given to the treatise, wherein he shews, how the geometer may assist his invention by such kind of computations. He frequently praised_ Slusius, Barrow _and_ Huygens _for not being influenced by the false taste, which then began to prevail. He used to commend the laudable attempt of_ Hugo de Omerique _to restore the ancient analysis, and very much esteemed Apollonius’s book De sectione rationis for giving us a clearer notion of that analysis than we had before. Dr._ Barrow _may be esteemed as having shewn a compass of invention equal, if not superior to any of the moderns, our author only excepted; but Sir_ ~ISAAC NEWTON~ _has several times particularly recommended to me_ Huygens_’s stile and manner. He thought him the most elegant of any mathematical writer of