An excellent history of the problem of longitude is detailed in the book 'Longitude' by Dava Sobel. There are great stories about the clocks leading up to the creation of H4, and many more details on the "injustice" that John Harrison felt.
Longitude particularly made me appreciate the craftsmanship that these inventors applied. Could you imagine spending 20 years building a single machine, not sure if it was going to work, then sending it off on a boat for 2 years and only when it comes back do you know if it worked? Makes me a bit more patient to wait 2 minutes for the test suite to run...
I've been plugging away (part-time) for three years. Sometimes it feels like a long time, but when you consider that Harrison spent decades on a much harder and worthwhile problem... Anyway, if anyone wants to help me with my "sea trials", I'd appreciate it. Here's an overview of my next release: