The building in the rear, used as the coinage department, has two arched and paved brick vaults in its basement intact except the doors. One of the vaults, illustrated opposite page 9, has a smaller vault in its rear end, which was undoubtedly used as a storage place for the most valuable of the mint’s possessions. Strong brick arches and exceedingly heavy joists, averaging twelve inches square, were placed in the basement to support the coinage presses above.
The building formerly facing Filbert Street had no basement, and when excavations were made for the new building two old brick-walled wells were uncovered, one of which was four feet in diameter, with cesspool refuse in the bottom. The other well was about seven feet in diameter and the bottom was not reached, as the excavations only went down about 12 feet. These wells were between the old building and Filbert Street. The larger one was three or four feet back of the centre of the property at 35 North Seventh Street, and the other was just off the southeast corner of the demolished building. It is quite likely that the largest well furnished water for the distillery of Michael Shubart.
It is interesting to note that in the excavations on the site of the old building, several copper coins and planchets were found, most of which are illustrated opposite page 20. Two worthy of mention are about the size of half-cents, but with small holes in the centre, one of them having a milled edge, the other a plain edge. They are supposed to be planchets for the excessively rare 1792 silver centre cents, which must certainly have been struck off at the mint, otherwise the planchets would not have been found there. The author now has these finds in his possession, as well as a collection of hand forged hardware taken off the old building.
On May 8, 1792, the director of the mint was authorized, with the approbation of the President, to purchase a quantity of copper for the coinage of cents and half-cents, and Congress also provided that when fifty thousand (50,000) dollars of such cents and half-cents had been coined notice should be given to the public in at least two newspapers, and that any attempt to pass other copper coins would result in their forfeiture.