Dismantling of H1 has progressed well and the timekeeper is now almost totally in pieces. As parts come off I'm taking the chance to look at them closely and am developing a much more detailed idea of the restoration carried out by Gould and the Chronometer Section in the 1960s.

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In spite of his descriptions of the restorations in his notebooks, Gould did not provide complete data, and I am now busy counting teeth on wheels, measuring parts and keeping a tally of the total number of parts in H1. Some statistics are proving quite surprising. For example, just the two fusee chains (which link the driving springs with the wheels of the clock) between them total almost 4,000 bits!

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Now that the wheels and roller bearings are all out it is becoming clear that the timekeeper is in very fine condition. Almost no wear is perceptible on the bearings, and Harrison's 'rolling contact' arrangement has stood the test of time extremely well. The only evidence of long use is what one might call the 'computer mouse' problem, where the rolling contact has caused thin layers of dust to become compacted on the rollers (just as it does inside the mouse sometimes).

Next is extensive photography and measuring, and I have to decide on the best (and most conservative) way to repair the broken balance spring connection.