Crawford, Brian Hewson
Brian Hewson Crawford was a British physicist who made important contributions to the science of vision, colorimetry, lighting, and color rendering.
Brian Crawford was born in 1906 and died in 1991. His first scientific publication was, as his mother’s ghostwriter, the Boy’s Own Corner of the Daily Mail. He went to the University College London, graduating with first-class honors in Physics at the age of 19. After a brief spell at the Rodenside Laboratory of the photographic company, Ilford, he joined the staff of the National Physical Laboratory (NPL) in 1927.
Having very wide interests, Crawford explored languages, painting, and music. His attitude to life was well illustrated by his remark after breaking his wrist in a fall from a bicycle that it had a reset at a more convenient angle for playing the viola. His honors included his Doctorate of Science from the University of London and his Newton Medal from the Colour Group (Great Britain).
Crawford worked in the NPL with W. S. Stiles under the leadership of John Walsh. A brilliant series of papers followed in the Proceedings of the Royal Society, on such new topics as equivalent backgrounds, increment thresholds, and, above all, the directional sensitivity of the retina to light and color known as the Stiles-Crawford effects. These were discovered during attempts to build a visual photometer based on pupillometry. The then “usual assumption that the apparent brightness of an object is proportional to the pupil area” was soon demolished [1, 2, 3].
Good fortune in research was characteristic of both Crawford and Stiles, but important discoveries fall only to those who deserve them. Crawford would say that you only had to search about in any field and you were bound to find out something interesting. No doubt this was so in his case. His 1947 Proc. Roy. Soc. paper on “Visual Adaptation in Relation to Brief Conditioning Stimuli”  is not obviously inspired by temporary blinding effects of gunfire flashes during the Second World War, but that was how “Crawford masking” was discovered. This is the effect whereby “a luminal stimulus begins to rise before the conditioning stimulus is applied to the eye.”
To compare and contrast the large-field colorimeters which Stiles and Crawford had each constructed in adjacent laboratories is an interesting exercise. Stiles’ machine was workshop built to the highest NPL precision and endowed with such facilities as a meteorology station of hygrometers, barometers, and thermometers, to monitor changes in the refractive index of the air. Crawford’s apparatus belonged to the string and sealing wax tradition, with corks for nonslip knobs and strips of graph paper for scales. Both instruments served their respective purposes admirably.
The successful early partnership and later divergence of Crawford and Stiles are perhaps explained by the creative tension between opposite natures. To draw an analogy from art, Stiles’ science was classic; like Nicolas Poussin, he had neglected nothing. Crawford was a romantic; he was fond of quoting Maxwell’s dictum that it is always worth playing a trombone to a petunia at least once, and you never know what might happen. But Crawford could work to the highest NPL precision and accuracy when required, as he did in determining the average scotopic spectral response of the human eye, which forms the basis of the present CIE definition . Not least was the difficulty of eliminating the effects of minute amounts of stray light and simultaneously discrediting data produced by several investigators who had not been so careful.
In his last years at NPL, Crawford studied the color rendering properties of artificial light sources, and he made a great breakthrough in convincing suspicious experts in art galleries and hospitals that certain fluorescent lamps were suitable for their exacting requirements . Typical of Crawford was his finding that combinations of tungsten filament lamps and “radar blue” fluorescent lamps could imitate almost perfectly any phase of natural daylight. The resultant equipment was essential in providing a transportable reference illuminant for the darker corners of the Victoria and Albert Museum and the Sheffield Royal Infirmary. He also studied color matching and adaptation .
Work in the conservation department of the National Gallery was continued by Crawford long after officially retiring from NPL. He also made investigations on color in the laboratories of the University of Edinburgh, the Paint Research Association, Imperial College, and the Institute of Ophthalmology. He went on publishing original papers until the age of 79, thus refuting the fallacy that scientific research is only for young people .
- 8.With the kind permission of the Colour Group (Great Britain), this account is based largely on the obituary written by Dr. D. A. Palmer and published in its newsletter. 17, 1 (1992)Google Scholar