The story of John (Longitude) Harrison is well known; how after many years of work, he developed a clock that would keep accurate time at sea. His goal was to win the Longitude prize, a glittering £20,000 offered in the Act of 1714. John's story is well recounted at all levels from the glossy booklet through the symposium proceedings, the popular book, the deep technical tome and the TV film. James Harrison, (James 4) was the great-grandson of James, John's brother. He worked in Hull making turret clocks between around 1826 and 1860. He died in 1875 and left at least 30 turret clocks that are known of today. James well knew his forebears horological knowledge and incorporated some of John's principles into his clocks. A key invention was a detached escapement that although it looked like a grasshopper, was in fact a gravity escapement. Other firsts for James were cast-iron wheels, expanding flys to regulate striking speed, an effective striking mechanism and skeleton cast-iron dials.But James 4 left more than what he bequeathed in his will, it was a spin-off from John Harrison's knowledge. This 'Longitude's Legacy' is exposed and explained. Much has been written about John Harrison, however, little has been told about the rest of the family. This book corrects some of this woeful shortfall providing a brief history of James Harrison, brother of the famous John. This James turned to bell hanging, bellfounding and milling after he had helped his brother with making of the regulators and the first sea clock. His son, Henry was a bellfounder too and was succeeded briefly by his son Henry. Henry died early in his life and the bellfoundry was then run by James 3. James 3 was eccentric but through a series of 100 plus letters in the Mechanics' Magazine provide a deep insight into his knowledge and character and this is explored in two chapters. A chapter is provided on the clockmaker William Wynn whose letters in the Mechanics' Magazine spurred responses from James 3. James 3 won two prizes from the Society for Arts, one for a detached escapement the other for expanding flys. His son, James 4 started with bells but then turned to turret clock making settling in Hull. He died in 1875 and left no issue.The books starts with necessary introductory chapters covering John Harrison and his quest for the longitude prize. Later family members are then covered followed by detailed information on James 3 and James 4. The largest chapter covers the clocks made by James 4. All known clocks are described and illustrated. In a somewhat unusual approach, over half the book is appendices. The majority of these are the letters that appeared in the Mechanics' Magazine and these are given for the interest of the reader and for the information of the serious researcher. Other details are letters written by James 4 and the various awards he received.The book will be of interest to anyone interested in clocks, particularly turret or tower clocks. Next, those who are fascinated by the Harrison story and want to know more about John 'Longitude's' wider family will find it useful. For churches that have a Harrison turret clock, and those who care for them, the book is a must. Finally local historians in the Lincolnshire, Yorkshire and Hull regions will discover more about their local man and clocks in their locality. Author Chris McKay is well known in the turret clock field both in historical and practical modes. It was in 1976 he saw his first Harrison turret clock and has been researching ever since. In explaining the book as 'a long time in the coming' he took advice from a friend and wrote the history 'just as it is'.