therefore, a well of sixty feet in diameter to dig down to a depth of nine hundred feet. This great work must be completed within eight months, so that you have 2,543,400 cubic feet of earth to excavate in 255 days; that is to say, in round numbers, 2,000 cubic feet per day. That which would present no difficulty to a thousand navvies working in open country will be of course more troublesome in a comparatively confined space. However, the thing must be done, and I reckon for its accomplishment upon your courage as much as upon your skill.” 

 At eight o’clock the next morning the first stroke of the pickaxe was struck upon the soil of Florida; and from that moment that prince of tools was never inactive for one moment in the hands of the excavators. The gangs relieved each other every three hours. 

 On the 4th of November fifty workmen commenced digging, in the very center of the enclosed space on the summit of Stones Hill, a circular hole sixty feet in diameter. The pickaxe first struck upon a kind of black earth, six inches in thickness, which was speedily disposed of. To this earth succeeded two feet of fine sand, which was carefully laid aside as being valuable for serving the casting of the inner mould. After the sand appeared some compact white clay, resembling the chalk of Great Britain, which extended down to a depth of four feet. Then the iron of the picks struck upon the hard bed of the soil; a kind of rock formed of petrified shells, very dry, very solid, and which the picks could with difficulty penetrate. At this point the excavation exhibited a depth of six and a half feet and the work of the masonry was begun. 

 At the bottom of the excavation they constructed a wheel of oak, a kind of circle strongly bolted together, and of immense strength. The center of this wooden disc was hollowed out to a diameter equal to the exterior diameter of the Columbiad. Upon this wheel rested the first layers of the masonry, the stones of which were bound together by hydraulic cement, with irresistible tenacity. The workmen, after laying the stones from the circumference to the center, were thus enclosed within a kind of well twenty-one feet in diameter. When this work was accomplished, the miners resumed their picks and cut away the rock from underneath the wheel itself, taking care to support it as they advanced upon blocks of great thickness. At every two feet which the hole gained in depth they successively withdrew the blocks. The wheel then sank little by little, and with it the massive ring of masonry, on the upper bed of which the masons labored incessantly, always reserving some vent holes to permit the 

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