The Diffusion Photometer

Abstract

IN the discussion before the Physical Society of June 9, a photometer made of paraffin blocks is mentioned as “The Jolly Photometer.” I think, however, that this is the photometer described by me in the Philosophical Magazine some two or three years ago; also in the proceedings of the Royal Dublin Society, and exhibited before the British Association on the occasion of their meeting at Bath. I cannot now give exact references, but I must be pardoned for calling attention to the mistake, as it has been made before by a high authority, and seems likely to be perpetuated in England.