Engraving of an experiment to test Captain Jerningham's idea to assist the launching of lifeboats. The launching of lifeboats from a beach into heavy breaking surf was often dangerous and sometimes impossible due to the strength of the waves. Captain Jerningham felt that if a mortar were used to fire one or two anchors out beyond the surf, a lifeboat could haul on these anchor lines to pull itself through the breakers and into the calmer water beyond.