Correspondence and documents dated between September 1849 and November 1850 relating to the development of the Moorsom System of tonnage measurement which became British Law in 1854. Printed documents include a mode proposed for determining the register of tonnage of merchant shipping by means of a system of internal measurements by G. Moorsom. Correspondence shows how the proposal was received at the time, and includes letters of support from various shipping interests, including ship builders Gilmours of Glasgow, and Hall & Co, ship owners of Aberdeen.

Administrative / biographical background
The subject of the report is how the cargo carrying capacity of seagoing vessels should be measured. This was important because taxes and harbour dues were calculated on tonnage. Previous methods known as ‘girting’, based on the external size of a sailing ship, were crude and did not take into account the great space devoted to boilers, bunkers, engines and coal necessary in steamers.