Mr. Barton and some others of Mr. Rittenhouse’s friends had repeatedly recommended to him to visit England: the former, particularly, often urged him to it, and for the reasons assigned in the text. That he had, himself, long contemplated that voyage, is apparent from the extract of his letter to Mr. Barton, of the 15th of March 1771, already quoted; and his last mentioned letter to the same gentleman shews, that, nearly a year afterwards, he still had that object steadily in view. Footnote 167: In a preceding letter, Mr. Barton had sent him some Mathematical Problems, for solution. These had been furnished by a schoolmaster, in Mr. Barton’s neighbourhood; who, although reputed a pretty good mathematician, possessed but a small share of genius or invention, while he had a large portion of confidence in his own abilities. In noticing these problems, Mr. Rittenhouse could not refrain from shewing some little irritation: he thought the communications too trifling, too destitute of originality, or too useless, to merit his attention; and, accordingly, he thus expressed himself on the occasion, in a letter dated Feb. 3, 1772: “I entreat you not to insist on my measuring heads with any pragmatical schoolmaster, who is heartily welcome, for me, to divert himself with his _x. y. z’s_, at which he may be very expert, and yet be, as you say, both ignorant and conceited. His first question, however, may be answered by any young algebraist: the second and third are more difficult, and will admit of various answers. The fourth contains four observations, picked out, (and carelessly enough, several of the figures being wrong,) of a set made on the comet of 1682, which I shewed your son William in about half a dozen different books; you will find them in Dr. Halley’s Astronomical Tables. Every thing relating to this comet has long ago been settled by Dr. Halley; so that, to give a complete answer to the question, I need only transcribe from him: but you cannot conceive how much I despise this kind of juggle, where no use is proposed. If your schoolmaster will give me but three good observations (I do not want four) of the comet of 1769, I will accept them with thanks, and soon undertake the laborious task of determining its orbit, which we yet know nothing about.” To this Mr. Barton replied, in a vein of good-humoured pleasantry: “I imagine you have mistaken me, with regard to the mathematical questions. They were not sent as trials of your abilities: but, for reasons with which W. B. is acquainted, and which I have desired him to give you, in order to afford you a laugh. I shalt never “insist” on your “measuring heads” with a “schoolmaster,” of any kind; because I know full well, already, that your head is longer than all the heads of the whole tribe. Had you known what diversion your solutions would have afforded me, you would have sent them.” -----