On the 5th of January, 1769, James Watt obtained a patent for a series of improvements in the steam-engine, one of which was most important in its bearing on naval engines. It was that which provided for steam acting _above_ the piston as well as below it, in, of course, the same cylinder. Here was a grand move at once. Previously every engine for pumping, the only practical purpose to which steam was yet put, was worked by a beam engine and pair of cylinders. In 1779, Matthew Wasborough, an engineer of Bristol, obtained a patent, as others, indeed, had before him, for converting a rectilinear into a continuous circular motion. It failed, as the others had done, because they required ratchet wheels, pulleys, &c. The following year James Pickard invented the present connecting-rod and crank, with fly-wheel, and removed the great obstacle to propelling vessels by steam. The following year, again, Watt invented what is now known as the “sun and planet motion,” another step in the same direction. We now approach the name of one of those who are most intimately connected with the history of steam navigation, Patrick Miller of Dalswinton. In 1787 he published a pamphlet(24) describing a _triple vessel_, propelled by paddle-wheels, and worked by cranks. In it he very distinctly says: “I have also reason to believe that the power of the _steam-engine_ may be applied to work the _wheels_, so as to give them a quicker motion, and consequently to increase that of the ship. In the course of this summer I intend to make the experiment,” &c. A statement was presented to the Royal Society, Dec. 20th, 1787, regarding experiments made by Mr. Miller in the Firth of Forth, the previous summer, in a _double_ vessel, sixty feet long and fourteen and a half feet broad, put in motion by a water-wheel, wrought by a capstan of five bars. On the lower part of the capstan a wheel was fixed, with teeth pointing upwards, to work in a trundle fixed on the axis of the water-wheel. She was worked at from three and a half to five miles an hour, with four or five men at the capstan. Two men propelled her at the rate of two and a half miles. The vessel was three-masted, and sailed well with a smart breeze, when the wheel was invariably raised above the surface of the water. “After making sundry tacks in the Firth,” says the narrator, “with all the sails set, the wind fell to a gentle breeze, when all the sails were taken in, and the following experiments made:— “The vessel being put in motion by the water-wheel, wrought by five men at the capstern (_sic_) was steered so as to keep the wind right ahead, and her going was found by the log to be three and a half miles in the hour. “After this the wind was brought on the beam (that situation being considered as the nearest to trying the effect of the wheel in a calm), when five men at the capstern made the vessel to go at the rate of four miles an hour.