When Bushnell learned that the candle used to illuminate instruments inside the "turtle" consumed the oxygen in its air supply, he turned to Benjamin Franklin for help. The solution: the phosphorescent weed, foxfire. Heavy tides thwarted the first sabotage operation. A copper-clad hull which could not be penetrated by the submarine's auger foiled the second. (The "turtle" did blow up a nearby schooner, however.) The secret weapon would almost certainly have achieved success against a warship if it had not gone to the bottom of the Hudson River when the mother ship to which it was moored was sunk by the British in October 1776.