One of the piers was sunk 110 feet below the surface of the river, through ninety feet of gravel and sand. Eads's theories were justified by finding the bed-rock so smooth and water-worn as to show that at times it had been uncovered. This was the deepest submarine work that had ever been done, and Eads tells us in his reports many interesting experiments he made in the air-chambers. In their dense atmosphere a candle when blown out would at once light again. This was before the days of electric lighting: otherwise we may be sure that that would have been used, as so many other modern inventions were. For the first time in any such work, the last pier sunk had telegraphic communications with the offices on shore; which must have been comforting to workmen starting out to their labor in the dead of winter with two weeks' provisions. The dense air of the chambers caused not only discomfort to the ears, but also in the case of some of the workmen a partial paralysis. There was no previous experience to go by, but every precaution seen to be necessary was taken; the hours of work were made very short, the elevator was provided, medical attendance and hospital care were given free. After the first disasters no man was allowed to work in the air-chambers without a doctor's permit. And it is known that in helping the sufferers with his private means, Eads was as charitable as ever. Out of 352 men employed in the various air-chambers, 12 died. Eads, with his wonted generosity of praise, printed in his yearly report the names of all the men who worked in the deepest pier from its beginning till it touched bed-rock. It is interesting to note in passing that of all the workmen in the blacksmith's yard only the head smith himself could lift a greater weight than the designer of the bridge.