Can it then be deemed unnatural, and will you not expect to hear, that upon the death of professor Rush, Dr. Barton became desirous of filling his chair? He accordingly applied for it, and was appointed some few months after the decease of his learned predecessor. This chair he held in conjunction with that of natural history and botany, till the day of his death. It was, however, his intention, had he lived, to resign the latter, perhaps about this time. He believed that the duties of a lecturer on natural history and botany required all the fire, the zeal, the bodily and laborious exertions of a young man. The energy and fervour he had once shown in teaching those branches, he believed himself no longer capable of, neither did he wish to substitute for the necessary perambulatory excursions with his botanical class (which had been always frequent) the tame and uninstructive lectures of an old, and, what is an inevitable consequence, of a closet teacher.—He well knew that demonstrative branches, like those of natural history, could neither be faithfully taught nor properly elucidated by a man whose age naturally made him prone to the more inactive pursuits of life. He had been eminent as a teacher of those sciences, because he was young and active—when he became older he was unwilling to detract from his well-earned reputation. Besides these motives, he had determined to devote the remainder of his life to the more important chair to which he had succeeded. In a conversation with me a short time after his accession to the practical chair, in which he stated his intention to keep that of natural history and botany but a year or two longer, he declared his firm determination to direct the concentrated powers of his mind to the fulfilment of the duties of his new professorship; and in his dedication of his Archaeologiae Americanae Telluris, &c., to Mr. John Mason Good, an eminent surgeon of London, with whom he had long been in habits of correspondence, he thus expresses himself: "It is my object to collect materials for a history of these extinct animals and vegetables, the remains or impressions of which are daily discovered in the rapid progress of American population and improvement. I can hardly flatter myself that my time, devoted as it must be to other, and to me more important pursuits, will ever permit me to prosecute these archaeological inquiries very far;" and in the preface of the same work he says, "I at one time, indeed, for some years toge-
