T45 table clock by Anthony Randall

A glazed table clock known as ‘T45’ by Anthony Randall, England, completed 1998. This clock incorporates an accurate reconstruction of parts, from the centre wheel onwards, of the mechanisms of John Harrison’s H4 and H5 timekeepers. The ‘T’ in the name references the two tensator mainsprings which drive the mechanism, and enable it to run for 8 days on a single wind, with a very constant driving force. The centre wheel drives a train remontoire via an internally cut third wheel. The remontoire rewinds an additional small spring, which provides the energy to drive the escapement, which is mounted on a platform at the top of the clock. Donated to the Clockmakers' Charity by the maker, Anthony Randall. Clockmakers' Museum No. 1535

Anthony Randall is one of the most skilled craftsmen of modern British horology. His clock T45 links to one of the most important pieces in the Clockmakers’ Museum collection – John Harrison’s marine timekeeper, known as H5, as well as his prize-winning timekeeper, H4. Randall’s clock was built to provide evidence in one way or the other, of the capabilities of Harrison's H4 and H5 design, so much debated ever since the 1760s. Tests on the 250 year-old original would not be fair evidence and only a newly made version might prove the real capabilities of the design. This T45 achieved with great results and demonstrates that H4 and H5 were not flukes or any kind of deception.