THE ARTESIAN WELL OF GRENELLE, AT PARIS.

The boring of this well by the Messrs. Mulot occupied seven years, one month, twenty-six days, to the depth of 1794-1/2 English feet, or 194-1/2 feet below the depth at which M. Elie de Beaumont foretold that water would be found. The sound, or borer, weighed 20,000 lb., and was treble the height of that of the dome of the Hospital des Invalides, at Paris. In May, 1837, when the bore had reached 1246 feet 8 inches, the great chisel and 262 feet of rods fell to the bottom; and, although these weighed five tons, M. Mulot tapped a screw on the head of the rods, and thus, connecting another length to them, after fifteen months' labour, drew up the chisel! On another occasion, this chisel having been raised with great force, sunk at one stroke 85 feet 3 inches into the chalk![[7]]

[7] The depth of the Grenelle Well is nearly four times the height of Strasburg Cathedral; more than six times the height of the Hospital des Invalides, at Paris; more than four times the height of St. Peter's, at Rome; nearly four times and a half the height of St. Paul's, and nine times the height of the Monument, London. Lastly, suppose all the above edifices to be piled upon each other, from the base-line of the Well of Grenelle, and they would but reach within 11-1/2 feet of its surface.—Year-Book of Facts, 1843.

"WET THE ROPES."

The property of cords contracting their length by moisture became generally known, it is said, on the raising of the Egyptian obelisk in the square facing St. Peter's, at Rome, by order of Pope Sixtus V. The great work was undertaken in the year 1586, and the day for raising the obelisk was marked with great solemnity. High mass was celebrated at St. Peter's, and the architect and workmen received the benediction of the Pope. The blast of a trumpet was the given signal, when engines were set in motion by an incredible number of horses; but not until after fifty-two unsuccessful attempts had been made, was the huge block lifted from the earth. As the ropes which held it had somewhat stretched, the base of the obelisk could not reach the summit of the pedestal, when a man in the crowd cried out, "Wet the ropes!" This advice was followed, and the column, as of itself, gradually rose to the required height, and was placed upright on the pedestal prepared for it.