Stroborama Backwash from a propeller blade rotating in a wind tunnel, c. 1925-1930. Photograph to the millionth of a second taken with the Stroborama. Work of Mr Valensi at the Institut de Mécanique des Fluides de Marseille. Vintage silver print with white retouching. Typewritten and handwritten captions on the back. 7.2 x 10.5 cmStroborama Backwash from a propeller blade rotating in a wind tunnel, c. 1925-1930. Photograph to the millionth of a second taken with the Stroborama. Work of Mr Valensi at the Institut de Mécanique des Fluides de Marseille. Gelatin silver print, enhanced with white gouache. Typed and handwritten captions on verso. 7.2 x 10.5 cm