Slide showing pedigree chart of origin of colour blindness. Slide shows black and white pedigree chart of origin of colour blindness. On the front of the slide frame, handwritten title reads: 'colour blindness'. There is a small sticker lower right corner which reads: 'William Hume, 1 Lothian Street, Edinburgh'. William Hume was a Scientific Instrument Maker at 1 Lothian Street in the 1890s, advertising regularly in the Transactions of Edinburgh Photographic Society. Late 19th - early 20th century