Conversation so far:
what happened inJames Watt's later years?
James Watt retired in 1800.
Why did James Watt retire in 1800?
It was the same year that James Watt's fundamental patent and partnership with Boulton expired.

Question: What else did they do after he retired?
Self-contained rewrite: What else did James Watt do after he retired when his fundamental patent and partnership with Boulton expired?