John Day (c. 1740 – died 22 June 1774[1]) was anEnglishcarpenter andwheelwright. He is the first recorded death in an accident with asubmarine.[2] With the financial support of Christopher Blake, an Englishgambler, Day built a wooden "diving chamber" without an engine. He attached his invention to the deck of a 50-tonsloop named theMaria, which Blake had purchased for £340. The sloop's hold contained 10 tons ofballast, and two 10-ton weights were attached beneath the keel which could be released from inside the diving chamber. An additional 20 tons of ballast would be loaded on theMaria after Day had been locked inside the diving chamber.[2][3][4]
Day claimed he had previously spent 6 hours underwater inEast Anglia in a different vessel.[5] He bet with Blake that he and his boat could descend to a depth of 130 feet (40 m) and stay underwater for 12 hours.[2][6] Blake lost his initial bets on the venture with other gamblers due to delays in the construction of the diving chamber that prevented Day from making the dive within an initially specified 3-month period.[1]
On 22 June 1774,[7] theMaria was towed to a location north ofDrake's Island (St. Nicholas' Island) inPlymouth Sound, offPlymouth, England.[4] Day took acandle, water and biscuits on board. The boat was equipped with ahammock for the passenger. After the boat was locked, the weights were loaded and the boat sank forever into the depths. Day had the calculation of thetrim completely wrong.[3] It has been speculated that Day may have died fromasphyxiation,[1]hypothermia[4] or catastrophic structural failure of theMaria and/or the diving chamber due to waterpressure.[2][4][6]
Nikolai Detlef Falck mounted a rescue attempt a month after Day's descent, believing that Day might be alive in a form ofsuspended animation, but without success. In 1775, Falck published a pamphlet,A philosophical dissertation on the diving vessel projected by Mr Day, and sunk in Plymouth Sound, about Day's experiment.[5] Day's death was the first recorded fatal accident involving a submarine.[3][5]
