Derek Pratt’s Reconstruction Of John Harrison’s H4, The World’s First Precision Marine Chronometer (Part 1 of 3)
Here we present the first part in a three-part series about the making of Derek Pratt’s H4 reconstruction. This part was written by Roger Stevenson, chief watchmaker at Frodsham. This article was first published in the British Horological Journal (BHJ) in February 2015 and we thank them for permission to republish it on Quill & Pad.