Watt was most grateful to Murdock for his unvarying assistance. In January, 1813, when Watt was in his seventy-seventh year, he wrote to Murdock, asking him to accept a present of a lathe "I have not heard from you," he says, "in reply to my letter about the lathe; and, presuming you are not otherwise provided, I have bought it, and request your acceptance of it. At present, an alteration for the better is making in the oval chuck, and a few additional chucks, rest, etc., are making to the lathe. When these are finished, I shall have it at Billinger's until you return, or as you otherwise direct. I am going on with my drawings for a complete machine, and shall be glad to see you here to judge of them." The drawings were made, but the machine was never finished. "Invention," said Watt, "goes on very slowly with me now." Four years later, he was still at work; but death put a stop to his "diminishing-machine." It is a remarkable testimony to the skill and perseverance of a man who had already accomplished so much, that it is almost his only unfinished work. Watt died in 1819, in the eighty-third year of his age, to the great grief of Murdock, his oldest and most attached friend and correspondent. Meanwhile, the firm of Boulton and Watt continued. The sons of the two partners carried it on, with Murdock as their Mentor. He was still full of work and inventive power. In 1802, he applied the compressed air of the Blast Engine employed to blow the cupolas of the Soho Foundry, for the purpose of driving the lathe in the pattern shop. It worked a small engine, with a 12-inch cylinder and 18-inch stroke, connected with the lathe, the speed being regulated as required by varying the admission of the blast. This engine continued in use for about thirty-five years. In 1803 Murdock experimented on the power of high-pressure steam in propelling shot, and contrived a steam-engine with which he made many trials at Soho, thereby anticipating the apparatus contrived by Mr. Perkins many years later. In 1810 Murdock took out a patent for boring steam-pipes for water, and cutting columns out of solid blocks of stone, by means of a cylindrical crown saw. The first machine was used at Soho, and afterwards at Mr. Rennie's Works in London, and proved quite successful. Among his other inventions were a lift worked by compressed air, which raised and lowered the castings from the boring-mill to the level of the foundry and the canal bank. He used the same kind of power to ring the bells in his house at Sycamore Hill, and the contrivance was afterwards adopted by Sir Walter Scott in his house at Abbotsford.