Records of Humber Conservancy and the Humber Ports (Records deposited by Associated British Ports and its Predecessors) > Humber Conservancy > Publications produced, or acquired by the Humber Conservancy Board > International Lighthouse Conference, 1929 > Conference of the Chiefs of Lighthouse Departments, London 1929: Theorem on the Refraction of the Pencils of Rays. Appliance to the calculation of the brightness by M. André Dargenton