An article in the contract decided that the Columbiad should be hooped with wrought-iron--a useless precaution, for the cannon could evidently do without hoops.

This clause was therefore given up.

Hence a great economy of time, for they could then employ the new system of boring now used for digging wells, by which the masonry is done at the same time as the boring.

Thanks to this very simple operation they were not obliged to prop up the ground; the wall kept it up and went down by its own weight.
This manoeuvre was only to begin when the spade should have reached the solid part of the ground.
On the 4th of November fifty workmen began to dig in the very centre of the inclosure surrounded by palisades--that is to say, the top of Stony Hill--a circular hole sixty feet wide.
The spade first turned up a sort of black soil six inches deep, which it soon carried away.

To this soil succeeded two feet of fine sand, which was carefully taken out, as it was to be used for the casting.
After this sand white clay appeared, similar to English chalk, and which was four feet thick.
Then the pickaxes rang upon the hard layer, a species of rock formed by very dry petrified shells.