In 1834, the British Imperial Troy Pound and Yard were destroyed by fire when the Houses of Parliament burned. New Imperial Standards were completed in 1855, and copies were presented to the United States. The Office of Weights and Measures subsequently adopted them as new standards to replace the Troughton Scale and the Troy Pound of the Mint. Toward both ends of Bronze Yard No. 11 are cylindrical wells containing inset gold plugs with 1-yard defining lines inscribed upon them.

Detail of Bronze Yard No. 11