Gentlemen A lot has been written about the Harrison H4, a true landmark in horology having huge practical impact in navigation back in the 18th century. I posted about it before (https://omegaforums.net/threads/longitude-book-review.86056/) but just found this really cool movie showing the working parts of a replica made of H4. It is a bit sad that the replica was started by Derek Pratt that didn't live to finish the job and asked Frodshams to have it completed. Apparently up to this day, it is still unknown in detail how the diamond pallets of the escapement were made by Harrison, quote: "These pallets are very small and potentially very difficult to make in natural diamond. Unfortunately, Harrison did not leave any clues as to how he produced them. The method for the shaping and correct polishing of the pallets in H4 has taxed the minds of many horologists and diamond experts ever since.". Seeing the moving parts and the description of the watch is quite interesting. I hope you enjoy it (video in the linked page): http://frodsham.com/commissions/h4/ See below a few photos: