Scottish chemist and physicist (1842-1923) best known for his invention of the vacuum flask. Superb matte-finish 6 x 7.75 photo of Dewar posing beside an impressive flask, affixed to its original 10.5 x 13.75 mount, boldly signed on the image in fountain pen. Reverse is imprinted with the name of the photographer, M. Olive Edis. In fine condition, with creasing to the mount.