Engraving depicting Niels Ryberg Finsen's original UV arc light used to treat various skin conditions, including Lupus. In the tubes placed at 45 to the arc light quartz lenses concentrated the ud rays and a column of running water absorbed heat. Repeated daily exposures of 1 1/4 hours necessary for beneficial effect. Niels Ryberg Finsen (1860-1904) a Faroese physician, scientist and Nobel Prize Laurette of Icelandic and Danish descent. Dated 20th century.