Short, crisp, and quite enjoyable history of the longitude problem. As a help to understand the mechanical devices described in this book, I looked at videos and animations of Harrison's chronometers available online. That helped a lot in understanding the scale of achievement of John Harrison. The author does not attempt to make a "what happened at the end?" mystery out of this story. The summary of what happened is stated right at the beginning. The author instead engages the reader by providing the context of the times, the details of the challenges, and so on. This approach works quite well.
Those of you who work in engineering will find the technology development challenges described in this book quite relatable!