Niccolò Tartaglia designs diving bell

[ 1551 ] Italian Niccolò Fontana Tartaglia publishes a treatise on retrieving sunken ships in which he proposes a bell device resembling a weighted hour-glass. The entire air supply is contained in a small dome at the top, which makes the design impractical. More than 400 years later, Al Giddings builds a replica that is tested by Pete Romano to a maximum depth of 9 m (30 ft).