This remains the canonical text for understanding John Harrison, the 18th century watchmaker who was eventually acknowledge as the one how solved the Longitude Problem.

This is a story about the Enlightenment and, therefore, about the birth of our Modern age. At the heart of the story is the conflict between the mechanical know-how of Harrison and the entrenched allegiances to Astronomy, which stretch back through the Scholastics of the Middle Ages to the ancient Greeks. (For more on this relationship, see Hans Blumenberg’s The Genesis of the Copernican World.)

Harrison’s challenge was to build a clock that could overcome all the challenges of telling-time at sea with accuracy — the key to solving the Longitude Problem from the perspective of a clockmaker. Pendulums are too volatile in the rolling seas, and changes in weather would also affect the accuracy of the clocks as metals would expand and contract in different conditions.

In the building of these clocks, we find time suddenly untethered from nature and embodied in a device that can travel through nature without disturbance. Time thus becomes mechanically abstract (after Newton had made it intellectually abstract), and we begin to see the possibilities of our dominant image of time becoming the face of a clock.

All four of the Harrison clocks can be seen at the Royal Observatory. H-1, 2 and 3 are all running. H-4 requires lubrication and therefore too much handling for it to be running.