Mr. Rittenhouse’s application to books, had, no doubt, been more regular and constant in the earlier part of his life; before I knew him well, or before I had accustomed myself to watch the progress of his mind. He was, certainly, profoundly, acquainted with the Principia and other writings of Newton, which he read partly in the original, and partly through the medium of translation. And although, within the period of my better acquaintance with him, his reading I have said, was not intense, he suffered no important discovery in philosophy to escape his notice. Although his own library was small, he had ample opportunities, through the medium of the valuable library belonging to the Philosophical Society, and other collections in Philadelphia, of observing the progress of his favourite studies in Europe. He took much interest in the discoveries of Mr. Herschel, whose papers he eagerly read as they arrived from Europe: and I well remember the time (in 1785) when he was engaged in reading Scheel’s work on Fire, which had recently appeared, in an English dress. He then assured me, that some of this great Swedish philosopher’s notions concerning the nature and the laws of heat, had long before suggested themselves to his mind.
The chemical discoveries of Crawford and Priestley solicited some of Mr. Rittenhouse’s attention, about the year 1785-1786, and for some time after. The brilliant discoveries of Priestley, in particular, were not unknown to him. Upon the arrival of this illustrious philosopher in Philadelphia, in 1794, Mr. Rittenhouse stood foremost among the members of the Philosophical Society in publicly welcoming the exiled philosopher to the country which he had chosen as the asylum of his declining years; and in expressing his high sense of his estimable character, and of the vast accessions which he had brought to science. I often met Dr. Priestley at the house of our friend. Their regard for each other was mutual. It is to be regretted that their immediate intercourse with each other could not be more frequent. Priestley had unfortunately chosen the wilderness, instead of the capital or its vicinity, as his place of residence: and Rittenhouse, alas! did not live two years after the arrival of Priestley in America.
On the death of Mr. Rittenhouse, Dr. Priestley wrote me a letter of condolence on the great loss which the publick had sustained; on the irreparable loss which I, in particular, had suffered. When the Doctor afterwards returned from Northumberland to Philadelphia, he discovered much solicitude to know from me Mr. Rittenhouse’s religious sentiments, and the manner and circumstances of his death; and he evinced no small satisfaction in receiving from me that relation which I have already given you, of the last hours, and of the last words, of one of the best of men.
Mr. Rittenhouse had not studied natural history as a science: but to some of the branches of this science he had paid particular attention; and upon some of them he was capable of conversing with the ablest, and the most experienced. In Botany, he was not acquainted with the scientific or classical names: but the habits, and in many instances, the properties of plants were known to him. I well recollect how great were his pleasure and satisfaction, in contemplating the Flora of the rich hills of Weeling, and other branches of the Ohio, when I accompanied him into those parts of our union, in the year 1785. In this wilderness, he first fostered my love and zeal for natural history. Upon his return from the woods, in the month of October, he brought with him, as ornaments to his garden, many of the transmontain plants of the state of Pennsylvania: and long before I knew that it grew wild in the vicinity of Philadelphia, upon the banks of his native Schuylkill, he had naturalized in his garden, the beautiful Silene virginica, which he designated with the name of “Weeling Star.”
It is a fact, that in the last months of his life he devoted a good deal of his time to an examination of the structure of the most important organs of plants. Acquainted with that doctrine which forms the basis of the sexual system, he was fond of examining plants during the period of their inflorescence: and I remember, with what apparent pleasure, he pointed out to me the tube in the styles of some of the plants which grew in his garden.
He had made many observations upon the buds of trees, some of which I think were new. I regret that the memorandums which he kept of these observations have not been found among his papers.
Not fifteen days before his death, he had finished the perusal of a German translation of Rousseau’s beautiful letters on Botany, which I had put into his hands.
Mr. Rittenhouse, like Newton and many other men of great talents, employed much of his time in the perusal of works on the subject of natural and revealed religion. This was, I think, more especially the case in the latter part of his life. Among other books which I could mention, I well recollect that he read the Thoughts of the celebrated French philosopher Pascall: and he acknowledged, that he read them with pleasure. But that pleasure, he observed to me, was diminished, when he learned, what was often the state of Pascall’s mind:—a state of melancholy and gloom: and sometimes even of mental derangement. At the time of his death, the American Philosopher was engaged in the perusal of Mosheim’s Ecclesiastical History: and he had just before finished the perusal of the Meditations of the Emperor Marcus Antoninus; that excellent work, replete with the sublimest morality, and with much of a sublime religion.
About three weeks before his death, I had put into his hands the first volume of Dr. Ferguson’s Elements of Moral and Political Science. I took the liberty of particularly directing his attention to the last chapter of the volume: the chapter on the future state. He read it with so much satisfaction, that he afterwards sent it to his elder daughter, with a request that she would peruse it.
The benevolent dispositions of our friend were well known to you. You have, doubtless, done justice to this portion of his character; yet permit me to mention a few detached facts, which have came under my own immediate notice, and the relation of which may serve to augment even your respect and veneration for Mr. Rittenhouse.