On 24 July 1837, Cocking arranged a trial of his parachute, which took the form of an inverted cone connected by three hoops. Attached to Charles Green's 'Royal Vauxhall' balloon, piloted by Green and Edward Spencer the balloon rose to 5000 feet (1524m) Cocking released his parachute but it failed due to a mechanical error. Cocking died as a result.