The man who put Bideford on the map.
During the eighteenth century, business in all the ports on the Atlantic coast of England was booming. This was due to increasing trade, both imports and exports, with the American colonies. There was thus a corresponding need for seamen versed in the maritime arts and related subjects, a need which was not met by a grammar school education. So George Donn, a native of Bideford and Benjamin’s father, set up a Mathematical School in Bridge Street, in which were taught all the skills needed for navigation, commerce, industry, surveying and, indeed, astronomy. George and his elder son Abraham taught there to begin with, but when Abraham died in 1746 his younger brother Benjamin took over from him. As well as teaching, he wrote many articles for magazines, mainly on mathematical and astronomical subjects (including one on eclipses that could be seen from Bideford).
It was at about this time that he embarked upon his most ambitious project. The Society of Arts announced that it would award a prize of £100 to anyone who could produce an accurate one inch to one mile map of an English county. Donn wrote to the Secretary, informing him of his intention to undertake ‘ the Surveying and Making (of) a New and Accurate Map of the County of Devon’. He managed to complete this task, but it cost him more than £1,900 to do so. He won the prize but still ended up considerably out of pocket, in spite of having 526 subscribers to the map.
The map itself contains many features which would later be incorporated in Ordnance Survey maps, but was unusual in that one of its main features was the inclusion of all the manor houses in Devon, of which there were 650, together with the names of the people who lived in them at the time.
In 1759, he married a Bidefordian, Mary Anne, daughter of Henry Wilcocks.
In 1764, Donn moved to Bristol, where he became Librarian to the City Library. The duties were light, so he was able to continue his cartographic activities, making a detailed map of Bristol and its environs, amongst other projects. He tried to set up another mathematical academy there, but was unsuccessful, so he set up his own academy at The Park, near St. Michael’s Church. When that failed, he went to live in Kingston, near Taunton.
In 1796, until he died, he was master of mechanics to King George III. He was held in high regard by his contemporaries, which included such figures as Erasmus Darwin, Samuel Taylor Coleridge and Josiah Wedgwood.
As well as being a cartographer and mathematician he made mathematical instruments, which he used in the many peripatetic lectures he gave.
He died impecuniously in 1798, leaving a widow, and a son, also Benjamin Donn, who became a priest in the Church of England, and minor cartographer.