Lawrence House Museum and the Cornishman who discovered Neptune using mathematics

By Ralph Gifford | 20 May 2011
a bubst of a man with short hair
A bust of John Couch Adams by Neville Northey Burnard© Cornwall Museums / Bernie Pettersen
The people of Cornwall are proud: proud of where they live, proud of their heritage and proud of their rugby team. However, their pride is most deeply felt when it comes to people from the county who achieved great things. People like Richard Trevithick, inventor of the steam engine, or Bob Fitzsimmons, who made boxing history as the sport’s first three-division world champion.  

But if you were to ask the average Cornish person who John Couch Adams was, the most likely answer would be a shrug of the shoulders. That is, unless they were from Launceston.

Once Cornwall’s capital, this old market town sits just a couple of miles west of the River Tamar and has an extraordinary history as well as an impressive castle.

Its famous son, John Couch Adams, was born and grew up just outside Launceston. He was a brilliant mathematician and astronomer who, among other things, discovered Neptune, our solar system’s fourth-largest and second-most distant planet – using only mathematics.

At the Lawrence House Museum in Launceston visitors can learn about this brilliant man, his life and his work.  

It’s a story of humble beginnings. Born in 1819 to poor tenant farmers from Lidcott Farm in Laneast, roughly eight miles from Launceston, John was the eldest of seven children. At the village school in Laneast he showed great academic potential and his teacher had to first teach himself algebra so that he could help the bright youngster.  

His finished his schooling in Devonport under the tutelage of Rev John Couch Grylls, a cousin of his poor but well-connected mother. As well as studying the classics, it is said he mastered mathematics by studying alone in the library at the Devonport Mechanics Institute.

a black and white copy of a painitng of a man in Victorian dress
© Courtesy Lawrence House Museum
In 1836 his mother inherited the small estate of Badharlick, and the additional revenue allowed him to go the University of Cambridge in 1839, where he entered as a sizar to St Johns College.

For four years he studied mathematics, finally graduating in 1843 as a Senior Wrangler (the best graduate in the university) with a First Class degree. He was immediately elected as a fellow of the university where he started work on the Uranus "problem".

Based on data published in 1821 by Alexis Bouvard, the concept predicted the orbit of Uranus using Newton’s Law of Motion and Gravitation. However, observations showed that its orbit had large deviations from the tables, and this subsequently led Bouvard to hypothesise a perturbing body.

Convinced by this theory, Adams worked on a series of calculations while at home in Cornwall on a summer vacation which would lead to the planet’s discovery.

In October 1845 he left his findings with the Astronomer Royal George Biddell Airy. These calculations proved the existence of another body mass that was affecting the orbit of Uranus. When Airy wrote to Adams for a full explanation, Adams failed to respond.  

It remains a matter of conjecture as to why Adams fell silent - he was known to be quite a nervous and disorganised individual who spent much of his time alone.

Whatever the reason, his silence left the door open for the French astronomer and mathematician Urbain Le Verrier, who had been working on the same conundrum. In November 1845 Le Verrier presented his findings to the Academies des Sciences in Paris.

a photo of a blue planet
A picture of Neptune taken by Voyager 2 in 1989© NASA
Back in Greenwich, Airy immediately initiated the race for England to find the undiscovered planet. The search began on July 29 1846 and, after Neptune’s discovery was announced in Paris in September of the same year, James Challis at Cambridge Observatory declared that he had already seen it in August using Adams’ calculations, but hadn’t been able to confirm the discovery as he didn’t have an up-to-date star map.  

Thus began a dispute as to who should be credited with the discovery of Neptune. In the end, both Adams and Le Verrier were given the credit, although at the time the French asserted that the English had "stolen Neptune".  

Nevertheless, in 1847 Queen Victoria offered Adams a knighthood, which he refused apparently out of modesty. He did take other honorary and respected positions, including Foreign Honorary Member of the American Academy of Arts and Sciences, Fellow of the Royal Society, Professor of Mathematics at St Andrews University and the Directorship of the Cambridge Observatory in 1861. He also found time to become the President of the Royal Astronomical Society on two occasions.  

He died in 1892 at the Cambridge Observatory and is buried in Cambridge near his home.

Back in Launceston, at the Lawrence House Museum, portraits of Adams are accompanied by a sculpture of this famous son by the enigmatic Victorian Cornish sculptor Neville Northey Burnard. The sculpture is one of the items featured in the History of Cornwall in 100 Objects.

Despite public acknowledgement of his work, Adams was a man who preferred to keep his pride to himself. Perhaps the next time you hear of a famous Cornish person it will be Mr Adams, the Cornishman who discovered Neptune.

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