GRAYSON, HENRY JOSEPH (1856-1918), designer of machine for ruling diffraction gratings, scientist,

was born in Yorkshire, England, in 1856 or early in 1857. He came of a family of market-gardeners, arrived in Victoria when about 30 years of age, and for some time worked as a nursery gardener. Becoming interested in science he joined the Field Naturalists' Club, made some study of botany, and did some work on the Diatoniaceae, a group of minute plants. This led to an interest in microscopy and before 1894 he had constructed a machine for making micrometer rulings on glass, the results being very good for that time. In 1897 some very beautiful work Grayson had done in cutting sections of plants led to his being given a position in the physiology department of the university of Melbourne under Professor Martin. He was afterwards transferred to the geology department, and in December 1901 accompanied Professor Gregory (q.v.) on his expedition to Central Australia. In the preface to The Dead Heart of Australia Gregory paid a special tribute "To my assistant Mr Grayson on whom much of the hard work of the expedition fell". In 1910 Grayson was associated with D. J. Mahony in the preparation of a paper on "The Geology of the Camperdown and Mount Elephant Districts" (No. 9 in the Memoirs of the Geological Survey of Victoria), and in the same year, while working at the university under professor Skeats, who succeeded Gregory, Grayson made a highly efficient apparatus for preparing rock sections, a description of which will be found in the Proceedings of the Royal Society of Victoria for the year 1911.

In the meanwhile Grayson had been perfecting his fine ruling work. References to it will be found in the Journal of the Royal Microscopical Society for 1899, p. 355; 1902, p. 385; 1904, p. 393; 1910, pp. 5, 144, 701 and 801; 1911, pp. 160, 421 and 449. In the 1910 volume, on pages 239 and 243, there is an interesting note by Grayson himself "On the Production of Micrometric and Diffraction Rulings". He had then succeeded in ruling 120,000 lines to the inch. From this time onwards much of his time was given to the preparation of a dividing engine for ruling diffraction gratings. In 1913 he was transferred to the national philosophy department of the university under Professor T. R. Lyle and was allowed to give his full time to the machine. In July 1917 he read a paper before the Royal Society of Victoria giving a full description of the machine, which was published with several plates in the society's Proceedings for that year. In the same year he was awarded the David Syme Research Prize of £100 by the university of Melbourne. He died on 21 March 1918 leaving a widow but no children.

Grayson was a modest, quiet man absorbed in his work and daunted by no difficulty. He was never content with anything less than the best, and would spend endless pains in the endeavour to get complete efficiency from his mechanism. Much work of the same kind was being done in America and other parts of the world, but no one in his time had equal success with Grayson.