It is supposed to have been somewhat about this time, that Mr. Rittenhouse exercised his ingenuity upon an object, which, though not of great importance, is nevertheless a matter of considerable utility and some curiosity; the invention of an Hygrometer, made wholly of wood. The simplicity of the construction of this instrument, renders it easily attainable by almost every one; and as it is found to answer, very well, the end for which more expensive instruments are often employed, it may be considered as being more generally useful. Descriptions of the construction, and principle of operation, of this Hygrometer, having been furnished to the writer through the obligingness of two of his friends,[212] a very concise account of it, drawn up from those descriptions, is given in the Appendix. ----- Footnote 212: Robert Patterson, Esq. Director of the Mint, and David Rittenhouse Waters, Esq. a gentleman bred to the law, and a grandson of the late Dr. Rittenhouse. The decease of Mr. Waters happened soon after: he died on the 4th of September, 1813, at the premature age of twenty-two years. Although he had just entered on the threshold of the world, this excellent young man exhibited many proofs of extraordinary attainments in literature and science, as well as of a superior genius. He appeared to have inherited from his maternal grandfather, congenial talents. In his life, his amiable disposition endeared him to all who had an opportunity of knowing his virtues: in his death, not only have his relatives and friends experienced an afflicting bereavement, but his country has sustained the loss of a citizen of great promise. ----- A circumstance shall be noticed in this place, which, although trivial in itself, will serve to shew the grateful sense entertained by our Philosopher of the merits of General Washington. It appears, that just about the time when the provisional articles of peace, concluded on between the United States and Great-Britain, were made known in America, Mr. Rittenhouse had forwarded to the General, at the head-quarters of the army, a pair of spectacles, and reading glasses,—as a small testimonial of his respect for the character and services of that great man. The terms of the letter that accompanied this little present, are not known to the writer of these memoirs; but, of what complexion they were, may be inferred from the General’s answer, which is in these words: “_Newburgh, 16th Feb. 1783._ “Sir, “I have been honoured with your letter of the 7th, and beg you to accept my sincere thanks, for the favor conferred on me, in the Glasses—which are very fine; but more particularly, for the flattering expressions which accompanied the present.