Twr Mawr Llanddwyn Lighthouse

Caernarfon harbour board commissioned improvements to a "day mark" (an unlit tower) in 1842, because of the proximity of Llanddwyn Point to the harbour bar. The light came into service in 1846. The lantern and fittings cost £250 7s 6d, including the adaptation of the earlier tower. The lantern, originally comprising six Argand lamps burning colzo oil and fitted with catoptric reflectors, was made by De Ville & Co, London. It projected a fixed red beam from a window on the ground floor of the attached "lean-to" building. This was visible over distance of five miles (in clear weather) between bearings of N.W. by N. and S.W. by W., to provide a marker for the entrance to Menai Strait. A black…