A very fine marine  chronometer purchased by the Royal Navy in February 1895 for £42 (the eqivalent of more than £7000 today). Documented history from a "Ledger of Receipts and Issues of Chronometers" shows its use aboard HMS Pioneer, HMS Terror, HMS Admiral Farragat and HMS Mistley. There are several returns to Johannsen from Portsmouth, Plymouth, Bermuda and Sheerness, taking the uninterrupted history until March 6th 1936, during which time the chronometer would have been examined, serviced and prepared for its next use.
 
Asmus Johannsen, born in Denmark, is listed in Watchmakers and Clockmakers of the World (Brian Loomes) as working in London from 1863 to 1937, with various addresses culminating in 149 Minories in 1865. He is also listed in Chronometer Makers of the World (Tony Mercer) as a "Great maker supplying other makers". The firm continued trading until 1937, and this chronometer would have been one of the last to be returned to its maker for servicing on March 6th 1936.
 
As is to be expected, this marine chronometer keeps excellent time. Accuracy in timekeeping is not the most important feature of a marine chronometer - the ability to keep consistent time in different conditions of temperature, weather and sea states is key to accurate navigation. In theory, a chronometer could gain or lose a minute a day, but if that "rating" is known, the navigator can make allowances in calculating a ship's position.