With no formal training or apprenticeship, John Harrison revolutionized clock making and succeeded in a lifelong quest to finally solve a problem that caused nightmares for all sea faring adventures. That nightmare is not knowing where you were. The sun could be used to determine your latitude but there was no way aboard ship to tell how far West (or East) you had sailed. This caused many deaths and much waste of time and money.
Knowing what time it was at a set point on the globe could tell you where you are. Because the difference in that time to local time (determined by the sun), directly correlates to your longitude.
Almost everyone else was attacking the problem via the planets/stars/sun/moon positions. Harrison, working alone, was sure he could create a time piece that would do the trick. When he started watches, even on land, lost minutes a day. As a navigation device that would not do.
I will stop there.
I highly recommended this book.
