With regard to the application of steam power to _locomotion on land_, it is remarkable enough that, when Watt's attention was first directed, by his friend Robison, to the steam-engine, "he (Robison) at that time drew out an idea of applying the power to the moving of wheel-carriages." "But the scheme," adds Watt, "was not matured, and was soon abandoned on his going abroad." In 1769, however, when he heard that a linen-draper, one Moore, had taken out a patent for moving wheel-carriages by steam, he replied: "If linen-draper Moore does not use my engine to drive his chaises, he can't drive them by steam." In the specification of his patent of 1784, he even described the principles and construction of "steam-engines which are applied to give motion to wheel-carriages for removing persons or goods, or other matters, from place to place," and in 1786, Watt himself had a steam-carriage "of some size under hand;" but his most developed plan was to move such carriages "on a hard smooth plane," and there is no evidence to show that he ever anticipated the union of the rail and wheel. Among Watt's mechanical recreations, soon after the date of the last of his steam-engine patents, were four plans of making lamps, which he describes in a letter to Argand; and for a long time lamps were made at Soho upon his principles, which gave a light surpassing, both in steadiness and brilliancy, anything of the kind that had appeared. About a year after, in 1788, he made "a pretty instrument for determining the specific gravities of liquids," having, he says to Dr. Black, improved on a hint he had taken. Watt also turned his "idle thoughts" toward the construction of an _arithmetical machine_, but he does not appear ever to have prosecuted this design further than by mentally considering the manner in which he could make it perform the processes of multiplication and division. Early in the present century Watt devised, for the Glasgow water-works, to bring pure spring-water across the Clyde, an articulated suction-pipe, with joints formed on the principle of those in a lobster's tail, and so made capable of accommodating itself to all the actual and possible bendings at the bottom of the river. This pipe was, moreover, executed at Soho from his plans, and was found to succeed perfectly.