Background: James Watt  (30 January 1736 (19 January 1736 OS) - 25 August 1819) was a Scottish inventor, mechanical engineer, and chemist who improved on Thomas Newcomen's 1712 Newcomen steam engine with his Watt steam engine in 1781, which was fundamental to the changes brought by the Industrial Revolution in both his native Great Britain and the rest of the world. While working as an instrument maker at the University of Glasgow, Watt became interested in the technology of steam engines. He realised that contemporary engine designs wasted a great deal of energy by repeatedly cooling and reheating the cylinder. Watt introduced a design enhancement, the separate condenser, which avoided this waste of energy and radically improved the power, efficiency, and cost-effectiveness of steam engines.
Context: Watt retired in 1800, the same year that his fundamental patent and partnership with Boulton expired. The famous partnership was transferred to the men's sons, Matthew Robinson Boulton and James Watt Jr. . Longtime firm engineer William Murdoch was soon made a partner and the firm prospered.  Watt continued to invent other things before and during his semi-retirement. Within his home in Handsworth, Staffordshire, Watt made use of a garret room as a workshop, and it was here that he worked on many of his inventions. Among other things, he invented and constructed several machines for copying sculptures and medallions which worked very well, but which he never patented. One of the first sculptures he produced with the machine was a small head of his old professor friend Adam Smith. He maintained his interest in civil engineering and was a consultant on several significant projects. He proposed, for example, a method for constructing a flexible pipe to be used for pumping water under the Clyde at Glasgow.  He and his second wife travelled to France and Germany, and he purchased an estate in mid-Wales at Doldowlod House, one mile south of Llanwrthwl, which he much improved.  In 1816 he took a trip on the paddle-steamer Comet, a product of his inventions, to revisit his home town of Greenock.  He died on 25 August 1819 at his home "Heathfield" in Handsworth, Staffordshire (now part of Birmingham) at the age of 83. He was buried on 2 September in the graveyard of St Mary's Church, Handsworth. The church has since been extended and his grave is now inside the church.
Question: what happened in his later years?. Whats the answer?
Watt retired in 1800, the same year that his fundamental patent and partnership with Boulton expired.