 At the same time, the two lighthouses were each provided with a medium-sized (third-order) catadioptric fixed optic designed by James Chance.In 1865 John Tyndall had succeeded Faraday as scientific adviser to Trinity House, remaining in post until 1883.In 1873 Professor Tyndall was engaged by Trinity House to conduct a series of experiments on the relative effectiveness of different types of fog signal.