them with those of his own invention, certainly seems to warrant the information he received on the subject. Although, perhaps, the first instance, it was to be by no means the last in which he was to suffer by the application of the “vos non "vobis " principle. But it was usual with him not to make any public reclamation of even his best-established rights, until forced to do so by a strong pressure; and then it was only in the most modest, cautious, and unobtrusive manner. CHAPTER VI. MR. WATT'S INTRODUCTION TO DR. BLACK, AND TO PROFESSOR ROBISON — EXPERIMENTS ON INVENTION OF SEPARATE CONDENSER, AND FURTHER IMPROVEMENTS ON THE STEAM-ENGINE. IT was at this time that the young artificer's earnest devotion to philosophical pursuits, as well as his amiable and virtuous dispositions, had gained him the approving notice and enduring friendship of Dr. Black; who, in 1756, was appointed Professor of Anatomy, and, in 1757, Professor of the Practice of Medicine, in Glasgow College. It was also in the commencement of the winter of 1758-9 that he made the acquaintance of another able and ardent student, imbued with predilections similar to his own, Mr. John Robison, afterwards, by Dr. Black's recommendation, appointed to succeed Dr. B. as Lecturer on Chemistry in the University of Glasgow; and who subsequently became eminent as Professor of Natural Philosophy in that of Edinburgh. Both of those learned persons, owing to the accidental circumstance of their testimony having been called for on occasion of infringements of Mr. Watt's patents, at a period nearly forty years subsequent to their first meeting at Glasgow, have left interesting narratives of the rise and progress of their intercourse with Mr. Watt, and of the origin of his first and greatest invention; which, as they do honour alike to their authors and their subject, we do not hesitate to place before our readers. That by Dr. Black, which is by much the shorter of the two, had never been noticed by any of the previous biographers of Watt, nor, indeed, did its existence appear to have been known to them; while from Dr. Robison's longer, but highly curious and im portant narrative, only a very brief extract was published by M. Arago. History of Mr. Watt's Improvement of the Steam-Engine. By JOSEPH BLACK, M.D.* "I became acquainted with Mr. James Watt in the year "1757 or 1758, at which time I was Professor of Medicine "and Lecturer of Chemistry in the University of Glasgow. "About that time Mr. Watt came to settle in Glasgow as a "maker of mathematical instruments; but being molested by some of the corporations, who considered him as an "intruder on their privileges, the University protected him by giving him a shop within their precincts, and by conferring on him the title of Mathematical Instrument Maker "to the University. 66 66 66 66 66 I soon had occasion to employ him to make some things "which I needed for my experiments, and found him to be a young man possessing most uncommon talents for mechanical "knowledge and practice, with an originality, readiness, and copiousness of invention, which often surprised and delighted me in our frequent conversations together. I also had many opportunities to know that he was as remarkable for "the goodness of his heart, and the candour and simplicity "of his mind, as for the acuteness of his genius and understanding. I therefore contracted with him an intimate "friendship, which has continued and increased ever since "that time. I mention these circumstances only to show "how it happened that I was thoroughly acquainted with the progress of his inventions, and with the different objects "that engaged his attention, while I remained at Glasgow, "and, in a great measure, ever since. 66 66 "A few years after he was settled at Glasgow he was "employed by the Professor of Natural Philosophy to examine "and rectify a small workable model of a steam-engine, which *The original document is in the hand-writing of Dr. Black. On the envelope in which it is enclosed, Dr. B. has written, "Mr. Watt's lawsuit, 1796-97." 66 66 "was out of order. This turned a part of his thoughts and "fertile invention to the nature and improvement of steamengines, to the perfection of their machinery, and to the "different means by which their great consumption of fuel might be diminished. He soon acquired such a reputation "for his knowledge on this subject, that he was employed to plan and erect several engines in different places, while at "the same time he was frequently making new experiments "to lessen the waste of heat from the external surface of the "boiler, and from that of the cylinder. 66 "But after he had been thus employed a considerable "time, he perceived that by far the greatest waste of heat "proceeded from the waste of steam in filling the cylinder "with steam. In filling the cylinder with steam, for every "stroke of the common engine a great part of the steam is "chilled and condensed by the coldness of the cylinder, before "this last is heated enough to qualify it for being filled with "elastic vapour or perfect steam; he perceived, therefore, "that by preventing this waste of steam, an incomparably greater saving of heat and fuel would be attained than by 66 any other contrivance. It was thus, in the beginning of "the year 1765, that the fortunate thought occurred to him "of condensing the steam by cold in a separate vessel or 66 66 apparatus, between which and the cylinder a communi"cation was to be opened for that purpose every time the "steam was to be condensed; while the cylinder itself might "be preserved perpetually hot, no cold water or air being "ever admitted into its cavity. 66 "This capital improvement flashed on his mind at once, "and filled him with rapture; and he immediately made a hasty trial of it, which satisfied him of its value, employing "for this purpose a large brass syringe which he borrowed "from a friend." Such is the first part of the concise, but emphatic and comprehensive account given by Dr. Black; the remainder of which we reserve till somewhat later in our narrative. In the meantime, we proceed to give the greater portion of that of Dr. Robison, which, entering more into detail, seems more entirely to place us, as it were, in the very presence, and reveal to us the whole course of thought and inquiry, of his inventive companion and friend. According to Mr. Watt's own statement, to Robison belongs the honour of having been the first who drew his attention to the subject of steamengines ;-in 1759 even suggesting their application to "the moving of wheel-carriages," and to other purposes. 66 66 Narrative of Mr. Watt's Invention of the Improved Engine. By PROFESSOR ROBISON.* My acquaintance with Mr. Watt began in 1758. † I "was then a student in the University of Glasgow, and studying the science which I now profess to teach, Natural Philosophy. The University was then building an astro"nomical observatory. Mr. Watt came to settle in Glasgow “as a mathematical and philosophical instrument-maker, "and was employed to repair and set up a very noble collec"tion of instruments bequeathed to the University by Mr. "Macfarlane of Jamaica, a gentleman well known to the "scientific world. Mr. Watt had apartments and a workshop within the College. I had, from my earliest youth, a great relish for the natural sciences, and particularly for "mathematical and mechanical philosophy. I was eager to "be acquainted with the practice of astronomical observation, "and my wishes were much encouraged by the celebrated "Dr. Simson, Professor of Geometry, Dr. Dick, Professor of "Natural Philosophy, and Dr. Moor, Professor of Greek ;gentlemen eminent for their mathematical abilities. Those gentlemen brought me with them into Mr. Watt's shop; and 66 66 66 |