Early Thirty-Hour Marine Chronometer

This early and unusual chronometer has a number of high-quality features that reduce friction, such as diamond endstones. The unique balance and temperature compensation suggest that Snellen was experimenting with the expansion and contraction of metals, among other innovations.

William Snellen likely made this chronometer shortly after reading Harrison’s H-4 specifications, which were published in 1767. Made in the Netherlands in 1770, this piece indicates how quickly longitude-related information disseminated across Europe. A chronometer nearly identical to this one was once mistaken for H-6, the chronometer made by John Harrison’s son William. Snellen was a great and innovative craftsman, but little of his work survives.