Board approved a policy to replace lighthouses in the interior. Around 100 of these complex structures were built on the Atlantic coast line from the Delaware and Chesapeake Bays down to the Florida Keys and Gulf of Mexico. One of the most famous towers was the Thomas Point Shoal Light - it has been called “the finest example of a screw pile cottage anywhere in the world.” On March 3, 1851, the U.S. Congress passed "An Act Making Appropriations for Light House, Light Boats, Buoys, &c.", leading to the creation of the United States Lighthouse Board to replace the Department of Treasury's Lighthouse Establishment as the governmental agency responsible for the construction and maintenance of all lighthouses and navigation aids in the United States. Lighting improvements The source of illumination had generally been wood pyres or burning coal but this was expensive, some lighthouses consuming 400 tons of coal a year. Candles or oil lamps backed by concave mirrors were used, often in large banks. The French conducted a series of tests between 1783 and 1788 with varying results. Smeaton's Eddystone lighthouse used 24 candles until 1810. The Argand lamp, invented in 1782 by the Swiss scientist, Aimé Argand, revolutionized lighthouse illumination with its steady smokeless flame. The Argand lamp had a sleeve-shaped candle wick mounted so that air could pass both through the center of the wick and also around the outside of the wick before being drawn into cylindrical chimney. This steadied the flame and improved the flow of air. Early models used ground glass which was sometimes tinted around the wick. Later models used a mantle of thorium dioxide suspended over the flame, creating a bright, steady light. The Argand lamp used whale oil, colza, olive oil or other vegetable oil as fuel which was supplied by a gravity feed from a reservoir mounted above the burner. The lamp was first produced by Matthew Boulton, in partnership with Argand, in 1784 and became the standard for lighthouses for over a century. John Richardson Wigham was the first to develop a system for gas illumination of lighthouses. He was given a grant by the Dublin Ballast Board in 1865 and he fitted his new gas 'crocus' burner at the Baily Lighthouse in Howth Head, giving an output 4 times more powerful than the equivalent oil lights. An improved 'composite' design, installed in the Baily light in 1868, was