LONDON (AP) -- Experts at London's National Gallery said on Friday they had discovered a new Leonardo Da Vinci picture, hidden underneath another painting by the Italian master. This is the first time a new Da Vinci has been discovered since the 1930s, when the "Ginevra de' Benci'' and "The Madonna of the Carnation'' were attributed to him. Experts using infrared techniques found the sketch hidden beneath the delicate brushstrokes of Da Vinci's "The Virgin on the Rocks,'' a powerful study of Christ's mother in a rather gloomy cavern that hangs in the National Gallery. The sketch shows a woman...