vacancy thus left at the top was repeatedly refilled, until all remained solid; the top was then pointed, and, when necessary, defended by a coat of plaster. When the whole of the foundation was in this manner brought to a level, some other means was necessary of attaining the like degree of security. For this purpose the central stone of the sixth course had a hole of one foot square cut quite through the middle. Eight other depressions of one foot square and six inches deep were also sunk at equal distances in the circumference. A plug of strong hard marble, from the rocks near Plymouth, one foot square and twenty-two inches in length, was set with mortar in the central cavity, and fixed firmly therein with their wedges. This course was thirteen inches in height, so that the marble plug, which reached through it, stood nine inches above the surface. Upon this the centre-stone of the seventh course was fixed, having a similar hole made in its centre, bedded with mortar and wedged as before. By this means no force of the sea acting horizontally upon the centre-stone, less than what was capable of cutting the marble plug in two, was able to move it from its place; and to prevent the stone the more effectually from being lifted, in case its bed of mortar should happen to be destroyed, it was fixed down by four trenails. The stones surrounding the central stone were dove-tailed to it in the same manner as before, and thus the courses proceeded with no other interruption than arose from the nature of the situation. Smeaton tells us that when the work had proceeded so far as to afford a level platform, the pleasure he took in it, and the novelty of the thing, led him to walk to and fro upon it with much complacency. But making a false step, and not being able to recover himself, he tumbled over the brink of the work down among the rocks on the west side. The tide had then retreated, so that no serious result happened, but in his fall he dislocated his thumb, and as no medical aid could be procured, he set it himself, and then returned to his work. It was more than six months, however, before he recovered the full use of his thumb. Owing to very boisterous weather, and repeated losses of the necessary materials left on the rock, the seventh course was not laid until the 7th of September. But Smeaton had the satisfaction to find that all the work actually completed, stood the utmost severity of the weather unmoved. At this time the sea became so calm that the work proceeded rapidly, and for three days in succession the top of the work was not wetted. The eighth course was completed on the 13th, but the weather again becoming unfavourable, the ninth was not finished until the 30th, and here Smeaton found it desirable to close the operations for this year.