From the rude mode by which light was obtained, the stone mullions which supported the cupola-roof became so much damaged, that in 1717 it was necessary to remove the light to the apartment below, till the light-room and upper works were restored. But the new light being so defective that it could not be seen at sea at a greater distance than six miles, many accidents and complaints arose, when it was determined to construct the light-room of iron instead of stone. By this means the light passed with less obstruction, and in 1727, after a lapse of ten years, it was again exhibited at its accustomed height and with increased brilliancy. The light was further improved in consequence of pit-coal being used instead of timber; and the interior of the roof was converted into a kind of inverted conical reflector, the point of which projected downwards, and its base extended nearly to the full size of the roof. Still, however, the light being exposed in an open chauffer, was little to be depended on at any great distance from the shore, so that about the year 1780 reflectors and lamps were introduced, and in 1822 the light received its last improvement by the introduction of Fresnel's beautiful apparatus.
Management of English Lighthouses--The Trinity House--Early History of this Corporation--Management of Lighthouses vested in--The Power of the Crown to grant Patents for Lighthouses--Recent Law for the Regulation of Lighthouses--Revenue of Corporation--Rates of Dues--How collected and disbursed--Constitution of the Corporation--The Public Lights of England.
It will now be necessary to give some account of the important institution to whose members is entrusted the management of Lighthouses, and of various interests connected with the Seamen and Shipping of this country. This is the Corporation of the Trinity House of Deptford Strond, whose full title is as follows:--'The Master, Wardens, and Assistants of the Guild, Fraternity, or Brotherhood of the most glorious and undivided Trinity, and of St. Clement, in the parish of Deptford Strond, in the county of Kent.'
The early records of this corporation were destroyed by fire in 1714, so that the origin of the institution cannot be precisely stated. But it appears that the purpose for which it was first established was, for the increase of correct information of the intricacies of navigation connected with the channels leading into the Thames, and with the river itself, and that the society was originally an association of seamen formed for the purpose of forwarding and assisting the attainment of the object.