Thomas Earnshaw, High Holborn, London, UK - Blue Plaques on Waymarking.com

The first practical marine chronometers were created by John Harrison in the late 18th century, effecively solving the "longitude problem". While star-sightings could provide an accurate latude, without a sufficiently accurate timepiece, one robust enough to be used on board ship, accurate caclulation of longitude was difficult, if not impossible. This is told in in Dava Sobel's exellent book "Longitude" [1].

Harrison's chronometers were a ground breaking proof-of-concept in the face of scepticism and outright opposition from the authorities. After Harrison's death in 1776, the race was on to mass produce marine chronometers, and to simplify Harrison's complex and expensive designs.

The two main players in this race were Thomas Earshaw and the father and the son duo of John Arnold and his son, John Roger. Earnshaw designed a key component, the "spring detent escapement"[2], and became involved in a bitter patent dispute with Arnold father and son.

In 1805 the Board of Longitude awarded equal amounts of £3,000 to Earnshaw and Arnold jr. Earnshaw bitterly protested, and in 1808 published "An Appeal to the Public", putting his side of the case. However, Earnshaw's 'naturally irritable habit' and blunt manner "caused almost the whole trade to turn against him" [3].

Although the dispute was never resolved to Earnshaw's satisfaction, he remained nonetheless a highly successful manufacturer.

Examples of Earnshaw chronometers are on display in the National Maritime Museum in Greenwich, UK [4] and the Powerhouse Museum in Sydney, Australia [5].

Plaque reads
Site of the business premises of Thomas Earnshaw 1749-1829 Noted watch and chronometer maker.

Links

1. Longitude, Dava Sobel Harper Collins
2. Earnshaw's Chronometer Escapement antique-watch.com
3. Longitude. An appeal to the public International League of Antiquarian Booksellers. This page contains a detailed history.
4. Marine Chronometer by Thomas Earnshaw National Maritime Museum, Greenwich, UK
5. Earnshaw Chronometer no.520 Powerhouse Museum, Sydney, Australia

Blue Plaque managing agency: London County Council Individual Recognized: Thomas Earnshaw Physical Address: 120 High Holborn London , UK WC1V 6RD Web Address: [Web Link]

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Date Logged Log User Rating   10/29/2011 Master Mariner visited it