The face of the rock was cleaned off during the brief intervals when it was bared by the sea, and rough stones and masonry were laid in concrete and continued solidly to a point 13 feet above high-water. Around this confined platform quarters were built for the handful of men who stayed on the rock during the periods of calm weather, as too much time was lost in travelling to and from the island, while there were risks of landing being interrupted by the swell. A temporary light was also placed in position while constructional work was proceeding, to warn navigation. The facilities also included a small forge for the fashioning upon the spot of the iron dogs and bolts whereby the stones were clamped together, and this proved highly convenient, except for one thing: when the water was somewhat rough and playful, the waves, striking the rock, flew into the air, soused the forge, and extinguished the fire. The preparations of the foundations proved exceedingly tedious. The rock is a very hard black porphyry, but the surface was so scarred with fissures and deep cracks that the whole of the upper surface had to be cleaned off, so as to remove all rotten and splintered rock in order to secure a firm, solid foundation. Then a circle 38 feet in diameter was marked off, and masons cut away all the rock around this line to a depth of about 20 inches and of sufficient width to take the stones--a trench, as it were. This work had to be executed during the short period of low-water, and a special schedule was prepared to insure the men concentrating the whole of their energies upon the task when opportunity offered. As the ebbing tide began to bare the space, the workmen were called, and they followed the receding water, never leaving the spot for meals, but toiling continuously until the returning tide drove them off. As a rule the men were sufficiently fleet to get clear untouched, although they delayed their retreat until the very last moment; but at other times the sea was a trifle quicker, and the men received an unexpected douche from a scurrying wave. When this trench had been cleared out and the face levelled, the outer ring of stones was laid and secured firmly in position. The inner space of the rock was left in its roughly trimmed condition, and was then buried beneath cement and rock to the level of the outer ring of stones, forming a platform ready to receive the mass of the tower. The outer ring was the main consideration, and the work had to be finished in such a manner that a tight joint was made with the rock, to resist the penetration of the water. When the men were compelled to lay down their tools for the coming tide, they hastily applied a thick covering of quick-drying cement to the work completed, thereby protecting it against the disintegrating and percolating action of the sea.