Radiography of paintings is a now well established technique in the art world but the earliest investigations were reported in the medical and scientific literature. The first radiograph of a painting is attributed^ to Walter König of Giessen, a former student of Röntgen, in 1896, but the details of his investigation are not well documented. Many years later König referred^ to 'a röntgen picture of an oil painting on wood, which was brought to me by a gentleman from Frankfurt.’