Lighthouse engineer. Born in Edinburgh, into a family of engineers. His grandfather and great-uncle had worked under Robert Stevenson on the Bell Rock Lighthouse (1807-11), and indeed he may have been a relative of John Rennie (1761 - 1821), the supervising engineer of that project.
Slight served as a civil engineer with the Northern Lighthouse Board in Edinburgh, working with the famous lighthouse builders David Stevenson (1815-86) and Thomas Stevenson (1818-87). Having been head-hunted by the Chilean Government, he moved to Chile in the 1890s where he was responsible for building a network of more than seventy lighthouses, beginning with Islote Evangelista in 1896. Thereafter he was appointed Head of Lighthouse Authority of Chile.
He died in Santiago (Chile) and lies buried in the Cementerio General de Santiago. The Chileans have named a lighthouse museum (at Punta Angeles) and a ship in his honour.
