At Glasgow, through the intervention of Dr. Dick, he was first employed in cleaning and repairing some of the instruments belonging to the college; and, after some difficulty, he received permission to open a shop within the precincts as "mathematical instrument maker to the University." Here Watt prospered, pursuing alike his course of manual labor and of mental study, and especially extending his acquaintance with physics; endeavoring, as he said, "to find out the weak side of nature, and to vanquish her." About this time he contrived an ingenious machine for drawing in perspective; and from fifty to eighty of these instruments, manufactured by him, were sent to different parts of the world. He had now procured the friendship of Dr. Black and another University worthy, John Robison, who, in stating the circumstances of his first introduction to Watt, says: "I saw a workman, and expected no more; but was surprised to find a philosopher as young as myself, and always ready to instruct me." It was some time in 1764 that the professor of natural philosophy in the University desired Watt to repair a pretty model of Newcomen's steam-engine. Like everything which came into Watt's hands, it soon became an object of most serious study. The interesting little model, as altered by the hand of Watt, was long placed beside the noble statue of the engineer in the Hunterian Museum at Glasgow. Watt himself, when he had got the bearings of his invention, could think of nothing else but his machine, and addressed himself to Dr. Roebuck, of the Carron Iron-works, with the view of its practical introduction to the world. A partnership ensued, but the connection did not prove satisfactory. Watt went on with his experiments, and in September, 1766, wrote to a friend: "I think I have laid up a stock of experience that will _soon_ pay me for the trouble it has cost me." Yet it was between eight and nine years before that invaluable experience was made available, so as either to benefit the public or repay the inventor; and a much longer term elapsed before it was possible for that repayment to be reckoned in the form of substantial profit. Watt now began to practise as a land-surveyor and civil engineer. His first engineering work was a survey for a canal to unite the Forth and Clyde, in furtherance of which he had to appear before the House of Commons. His consequent journey to London was still more important, for then it was that he saw for the first time the great manufactory which Boulton had established at Soho, and of which he was afterward himself to be the guiding intelligence. In the meantime, among his other performances, he invented a micrometer for measuring distances; and, what is still more remarkable, he entertained the idea of moving canal-boats by the steam-engine through the instrumentality of a _spiral oar_, which as nearly as possible coincides with the screw-propeller of our day.