Spalding's diving bell. Historical illustration of Spalding's diving bell. The bell consisted of a lead-covered truncated wooden cone, 2.4 metres in height. Two small barrels were raised and lowered alternately to supply fresh air. One is seen renewing the bell's air supply at lower right. A tap (centre) in the side of the bell was opened and closed to remove foul air. This bell is an evolution of an original system by Edmund Halley, who is credited with inventing the first practical diving bell. He reported that five people were able to remain underwater at a depth of 18 metres for 90 minutes. Illustration from a book published in 1815.