Harrison decoded : towards a perfect pendulum clock Brings together the output of a forty year collaborative research project that unpicked and put into practice the fine details of John Harrisons extraordinary pendulum clock system. Harrison predicted that his unique method of making pendulum clocks could provide as much as one hundred times the stability of those made by his contemporaries. However his final publication which promised to describe the system was a chaotic jumble of information much of which had nothing to do with clockwork. One contemporary reviewer of Harrisons book could only suggest that the end result was a product of Harrisons superannuated dotage. 0The focus of this book centres on the making adjusting and testing of Clock B which was the subject of various trials at the Royal Observatory Greenwich. The modern history of Clock B is accompanied by scientific analysis of the clock system Clock Bs performance the methods of data gathering alongside historical perspectives on Harrisons clockmaking that of his contemporaries and some evaluation of the possible influence of early 18th century scientific thought