Pocket Chronometer

The pocket chronometer with the serial number 1289 pictured here was made in 1828 by Johann Heinrich Kessels (1781–1849), a manufacturer of precision clocks in the formerly Danish town of Altona. The Danish King Frederik VI. (1768–1839) presented it to Alexander von Humboldt (1769–1859) as a gift.

The clock is about the size of a pocket watch and has a dial with Roman numerals. The clock’s especially large and easily construed second hand, which has its own small dial in the lower part of the clock, is particularly noteworthy. Humboldt was keen on the clock because of his failing eyesight. The clock could be hung in a brass ring that itself hung freely in a wooden box for purposes of transport.

Explorers normally took a number of such high precision chronometers with them on long-distance expeditions. The HMS Beagle, the ship used by Charles Darwin (1809–1882) on his expedition to South America, was found to have 22 chronometers on board at the end of the voyage, eleven of which were still functioning perfectly.