Henry Raper was a British

British people

The British are citizens of the United Kingdom, of the Isle of Man, any of the Channel Islands, or of any of the British overseas territories, and their descendants...

 Royal Naval

Royal Navy

The Royal Navy is the naval warfare service branch of the British Armed Forces. Founded in the 16th century, it is the oldest service branch and is known as the Senior Service...

 lieutenant

Lieutenant

A lieutenant is a junior commissioned officer in many nations' armed forces. Typically, the rank of lieutenant in naval usage, while still a junior officer rank, is senior to the army rank...

 who became a nineteenth-century authority on navigation

Navigation

Navigation is the process of monitoring and controlling the movement of a craft or vehicle from one place to another. It is also the term of art used for the specialized knowledge used by navigators to perform navigation tasks...

. Amongst his achievements was his quantification of the unreliability of a key longitudinal

Longitude

Longitude is a geographic coordinate that specifies the east-west position of a point on the Earth's surface. It is an angular measurement, usually expressed in degrees, minutes and seconds, and denoted by the Greek letter lambda ....

 measurement, lunar distance

Lunar distance (navigation)

In celestial navigation, lunar distance is the angle between the Moon and another celestial body. A navigator can use a lunar distance and a nautical almanac to calculate Greenwich time...

, when taken at different times. One early beneficiary of Raper's research was Robert FitzRoy

Robert FitzRoy

Vice-Admiral Robert FitzRoy RN achieved lasting fame as the captain of HMS Beagle during Charles Darwin's famous voyage, and as a pioneering meteorologist who made accurate weather forecasting a reality...

, whose second expedition was made famous by the work of his travelling companion, Charles Darwin

Charles Darwin

Charles Robert Darwin FRS was an English naturalist. He established that all species of life have descended over time from common ancestry, and proposed the scientific theory that this branching pattern of evolution resulted from a process that he called natural selection.He published his theory...

.

Raper is primarily remembered, however, for his seminal work The Practice of Navigation and Nautical Astronomy, for which he was awarded the Founder's Medal of the Royal Geographical Society

Royal Geographical Society

The Royal Geographical Society is a British learned society founded in 1830 for the advancement of geographical sciences...

 in 1841. According to his memorial at St. Peter and St. Paul's Church, Dinton

Dinton, Buckinghamshire

Dinton is a village in Buckinghamshire, England. It is in the very south of the Aylesbury Vale on the ancient turnpike leading from Aylesbury to Thame . Dinton with Ford and Upton is also a civil parish within Aylesbury Vale district.The village name is Anglo Saxon in origin, and means 'Dunna's...

, it was "a work universally adopted by the naval service".

Raper died on 6 January 1859 at Torquay

Torquay

Torquay is a town in the unitary authority area of Torbay and ceremonial county of Devon, England. It lies south of Exeter along the A380 on the north of Torbay, north-east of Plymouth and adjoins the neighbouring town of Paignton on the west of the bay. Torquay’s population of 63,998 during the...

 in Devon

Devon

Devon is a large county in southwestern England. The county is sometimes referred to as Devonshire, although the term is rarely used inside the county itself as the county has never been officially "shired", it often indicates a traditional or historical context.The county shares borders with...

, England

England

England is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west; the Irish Sea is to the north west, the Celtic Sea to the south west, with the North Sea to the east and the English Channel to the south separating it from continental...

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