On 23 December 1788, Thompson seriously fractured his tibia, forcing him to spend the next two winters at Cumberland House convalescing. It was during this time that he greatly refined and expanded his mathematical, astronomical, and surveying skills under the tutelage of Hudson's Bay Company surveyor Philip Turnor. It was also during this time that he lost sight in his right eye.
On 23 December 1788, Thompson seriously fractured his tibia, forcing him to spend the next two winters at Cumberland .House convalescing. It was during this time that he greatly refined and expanded his mathematical, astronomical, and surveying skills under the tutelage of Hudson's Bay Company surveyor Philip Turnor It was also during this time that he lost sight in his right eye.