Having completed his observations, he moved to Cardiff in 1839 to supervise the construction of the Bute Dock which he had designed. His observatory was dismantled and the telescope was sold to Dr John Lee, who re-erected it in a new observatory of Smyth's design at Hartwell House near the village of Stone in Buckinghamshire. Smyth moved to Stone in 1842 and, still having access to the telescope, performed a large number of additional astronomical observations from 1839 to 1859. The telescope is now in the Science Museum, London.