of his career he had supplied most of the world's leading observatories with equipment. Simms' work formed the basis of the treatise on mathematical instruments written by his younger brother Frederick Walter Simms, who went on to become an important writer on civil engineering. His reputation was enhanced by the improvements he made to graduating instruments and his self-acting circular dividing engine reduced the work involved in manufacture from weeks to hours. He also helped standardize the measures of length the yard and chain for the Admiralty. Simms was elected an Associate of the Institution of Civil Engineers in 1828. He was a Fellow of the Royal Astronomical Society, which he joined in 1831, and elected a Fellow of the Royal Society in 1852. Simms died at the family home in Carshalton on 21 June 1860 and was buried at West Norwood Cemetery. His family, most especially his son James Simms carried on his instrument making work. Honours Simms Rock in Antarctica is named after William Simms. See also List of astronomical instrument makers References 1793 births 1860 deaths People associated with astronomy British scientific instrument makers Fellows of the Royal Society Burials at West Norwood Cemetery Engineers from London