Two-Day Marine Chronometer

Built to be read at a glance

A marine chronometer is built to do one thing without fail: hold true time at sea so a navigator can fix his longitude, and everything about this one is arranged to that end. The movement sits in a gilt brass bowl, swung in gimbals so it stays level however the ship moves beneath it, and the whole assembly locks into a two-tier mahogany box with a glazed inner lid, so the time can be read without opening the case to the air.

The dial is silvered, with black Arabic numerals and an outer minute track, laid out for fast and unambiguous reading. Subsidiary seconds sit low on the dial, at seven, and a second small dial at one carries the Auf and Ab scale, running from zero to fifty-six: the up-and-down indicator that shows at a glance how much of the two-day run remains before the chronometer must be wound. The hour and minute hands are gilt spades; the seconds and up-and-down hands are blued steel. Winding and hand-setting are done from the back, with the tipsy key that is still here on its bracket inside the lid.

What sets this example apart is that it is whole. Most of these wartime chronometers left Glashütte with bowls and gimbal rings of bakelite, a material that discolours, shrinks and cracks with the decades. This one keeps its gilt brass bowl and brass gimbals, and they have held their finish. The mahogany box is sound, its brass drop handles and locks work, and the bevelled glasses in both the bowl and the lid are clear.

It is also complete in the way that matters most on an instrument like this: the numbers agree. The same series number runs through the movement, the dial, the dust ring and the bowl, so the chronometer in front of you is the chronometer as it was finished and delivered, not an assembly of parts gathered together later.