Work began on the reef in August of 1756, with the gradual cutting away of recesses in the rock which were designed to dovetail in due course with the foundations of the tower. During the winter, the workers stayed ashore and were employed in dressing the stone for the lighthouse; work then resumed on the rock the following June, with the laying of the first courses of stone. The foundations and outside structure were built of local Cornish granite, while lighter Portland limestone masonry was used on the inside. As part of the construction process, Smeaton pioneered 'hydraulic lime', a concrete that cured under water, and developed a technique of securing the blocks using dovetail joints and marble dowels. Work continued over the course of the following two years, and the light was first lit on 16 October 1759.