Longitude is a short tale of an individual from an indistinct background and minimal education, striving to solve one of the most difficult conundrums of his day, through patience, diligence and a monumental attention to detail, combined with the exertions of half a century of labour. The story has plot twists and setbacks, rivals and allies, and if one wishes to stretch the imagination a little, even a villain. And of course, it’s all true.

In many ways, this book is little out of the ordinary, or at least its subject matter isn’t. Over the past few centuries this world has produced many remarkable personages: daring adventurers, shocking geniuses, revolutionary thinkers, and in this instance, plain hard-working pioneers. The age of discovery was perhaps particularly fertile in producing such remarkable characters, and a complete survey of the eighteenth century could easily fill a small library.

Which is precisely why Sobel’s book is so charming. In a period so active, a society so effervescent with ideas, Sobel has picked one lonely character, and one particular problem, and distilled a story that any layman can pick up and read. Despite the prominent cast of characters, the Isaac Newtons and Edmund Halleys, James Cooks and astronomers royal, the book in its entirety stretches to just 175 pages, and that in a fair spaced typeset. This brevity is precisely the book’s strength. The story needs no embellishment, it virtually tells itself, each iteration of John Harrison’s timepiece carried its own chapter heading in his life, each page a new development in the search for accurately keeping longitude at sea. Where many other books of this sort ramble on for a few hundred more pages about things entirely unpertinent to the theme, Sobel’s Longitude is concise and self-explanatory. What longitude is, how it proved such a problem to calculate, what rival solutions to the problem were being developed, and how John Harrison managed to essentially solve the riddle in one swoop, in a manner completely against the contemporary views of the time, all are clearly outlined and explained in this wonderfully distilled book.