Harrison's Chronometer H1 John Harrison, 46 years old, trials his first marine chronometer H1, built last year, on a round trip between London and Lisbon. A total failure on the way outward - it lost time -, the way back brings an encouraging success in the form of a precise landing against a 60-mile error in longitude for the traditional method of navigation by dead reckoning and by position shift through sun observation. This unexpected half-success rouses the Board of Lon