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 in 1841. According to his memorial at St. Peter and St. Paul's Church, Dinton, it was "a work universally adopted by the naval service". Raper died on 6 January 1859 at Torquay in Devon, England.