Blinded by the light

This item, from the Bartholomew Archive Printing Record, is a stark contrast to and visually unique from anything else that I have found. It pre-dates Piet Mondrian’s self styled Neo-Plasticism by a good 25 years and whilst you could be forgiven for thinking it was a work of art, as it happens, this is science.

This is a colour chart, not of the paint variety but related to a case of colour blindness. It was printed by Bartholomew on the 9 December, 1895 and ran to 780 copies. Printed for the Transactions of the Royal Society of Edinburgh it accompanied an article revealing the strange case of Mr A.

Mr A. was a patient of Dr William Peddie, or perhaps more accurately a subject of Dr William Peddie. Dr Peddie was not a medical doctor as you might expect but rather a physicist. He was born on Papa Westray in 1861, going on to study science at the University of Edinburgh. After graduation, he eventually rose to the position of Harris Chair of Physics at University College, Dundee, a post held by him for 35 years. He died only comparatively recently, in 1946. One of his particular interests and fields of expertise was colour vision which explains his link to the case. As it happens, he was also a Fellow of the RSE and consequently an unsurprising contributor to their Transactions.

Appearing in the 38th edition, Peddie’s article is a brief but interesting insight into Mr A.’s condition and how such matters were dealt with by scientists in 1895. Numerous methods and instruments are mentioned including quartz plates, colour discs and colourful powders. There are of course the obligatory equations such as 180 R + 180 B = 133 R + 60 W + 167 Bk. The result of these investigations led Dr Peddie to believe that Mr A. was probably dichromatic rather than monochromatic, a paradox which suggests that he could see both no and some colours at the same time. It appears that there was still much to be learnt by Dr Peddie’s generation.

So to the significance of the chart. This is a representation of how you would have seen the world had you been Mr A. Mr A. lacked the ability to distinguish certain colours from one another with differences that might seem blatant to most people meaning nothing to him. To Mr A. the colours in the first column, as you go from top to bottom, were all identical, the same with the second column. He was also unable to distinguish between the top and bottom pairs of colour in the third column although somehow he knew that they were different. In Peddie’s opinion Mr A. was blind to all colours except red.