Soon after entering, they reached the chapel of Saint Anthony, excavated in the times of the Byzantines, supported by columns, with altar, crucifix, and life-size statues of saints. They appeared, from being coated with smoke, to be of black marble, but Mark, putting his tongue to the nose of one of the saints, discovered it to be of salt. Many of the saints, however, were disappearing before the damp, which enters in that higher region from the upper world. The heads of some, and the limbs of others had already fallen. The guide had come provided with some Bengal lights, one of which he kindled on the altar, bringing into light this strange temple; then, as the flame burnt out, the whole vanished as if by magic. Passing across a wooden bridge, resting on piers of salt, they entered a vast irregular vault in which were two obelisks of salt, to commemorate the visit of Francis the First and his empress. As they reached the floor, a boy ran along the bridge above with a burning Bengal light, which threw flashes of blue lustre on the obelisks, the scarred walls, the vast arches, the entrance to the deeper halls, and the lofty roof, fretted with the picks of the workmen. Another hall was entered, with cavernous tunnels at the farther end, passing through one of which, they embarked upon a lake in a heavy, square boat, and entered a gloomy passage, over the entrance to which was inscribed, in salt letters, "Good luck to you." Midway in the tunnel the halls at either end were suddenly illuminated, and a crash, as of a hundred cannon bellowing through the vaults, shook the air in such a way that the boat had not ceased to tremble when they landed in the farther hall. The noise was produced by a single gun. A tablet, on which was inscribed, "A hearty welcome," greeted them on landing. At a depth of 450 feet their journey ceased, although they were but half-way to the bottom. About 1500 men are employed in the mines, who labour only six hours at a time, and live in the upper world. The blocks are first marked out on the surface by a series of grooves. One side is then deepened to the required thickness, and wedges being inserted under the block it is soon split off. This salt bed occupies a space of 9000 feet in length and 4000 in width, and consists of five successive stages, separated from each other by intervening strata of from 100 to 150 feet in thickness, and reaching to the depth of 1500 feet.