Thus equipped, he began in 1886 the investigations on the temperature of the sun and the radiation from sunspots, which were remarkable pioneer work. In 1894 he published, with Philip Leman Gray, his ‘Experimental Investigation on the Effective Temperature of the Sun’ (Phil. Trans. 185A, p. 361), in which he arrived at the result 6590° C. This, with other important papers, published in the Phil. Trans. and Monthly Notices of the Royal Astronomical Society, and a selection of his admirable celestial photographs were collected in a volume, ‘Astronomical and Physical Researches made at Mr. Wilson's Observatory, Daramona, Westmeath,’ printed privately in 1900. Subsequent work included an examination of the effect of pressure on radio-activity, and an expedition to Plasencia to observe the solar eclipse of 1900. He was elected F.R.S. in 1896, and was made hon. D.S. of Dublin University in 1901.
Wilson, who mainly lived on his estate, was high sheriff of co. Westmeath in 1901.
He died at Daramona on 6 March 1908, and was buried in the family burying ground attached to the parish church of Streete, the village adjoining his demesne. There is a portrait in oils at Daramona, painted in 1886 by E. Marshall.
He married on 10 Nov. 1886, Caroline Ada, third daughter of Captain R. C. Granville of Grand Pré, Biarritz, and left one son, John Granville, and two daughters.
[Royal Soc. Proc., 83 A., 1910; Monthly Notices Roy. Astron. Soc., lxix. Feb. 1909.]
WIMSHURST, JAMES (1832–1903), engineer, born at Poplar on 13 April 1832, was the second son of Henry Wimshurst, designer and builder of the Archimedes and Iris, the first two screw-propelled ships. After education at Steabonheath House, a private school in London, he was apprenticed at the Thames Ironworks to James Mare. In 1853, on the completion of his apprenticeship, he obtained an appointment in London as a surveyor of Lloyds. He was subsequently transferred to Liverpool, where in 1865 he was made chief of the Liverpool Underwriters' Registry, then a rival establishment to Lloyds, but since incorporated with it. In 1874 he joined the board of trade as chief shipwright surveyor in the consultative department. He attended as its representative the international conference at Washington in 1890, and retired on reaching the age limit in 1899.
Through life Wimshurst devoted his leisure to experimental work, erecting at his house in Clapham large workshops, which he fitted up with various engineering appliances and where he also built electric-lighting machinery. About 1880 he became interested in electrical-influence machines, and built several of the then current types, including machines of the Holtz and Carré patterns. In the former he made many modifications, the result being a plate machine remarkably independent of atmospheric conditions. This was followed by a compound machine of the same type in which there were twelve plates revolving between twenty-four rectangular glass inductor plates, and which had a miniature friction plate machine for producing the initial charge. The result, however, did not satisfy Wimshurst, and shortly afterwards he invented what he called the ‘duplex machine,’ but what is generally known simply as the ‘Wimshurst machine.’ It had two circular plates rotating in opposite directions with metallic sectors on the outer surface of each. This machine displaced all previous generators of static electricity, being self-exciting under any atmospheric condition. It has never been improved upon. In all Wimshurst constructed more than ninety electrical-influence machines, including the gigantic two-plate machine in the Science Collection at South Kensington. Many of his machines he presented to scientific friends. Some had cylindrical plates, and one was designed with two ribbons which travelled past each other in opposite directions. He took out no patents for his improvements, and was consequently precluded from exercising control over the design or construction of inferior machines put upon the market in his name.
In 1896 Wimshurst found his machines to be an admirable means of exciting the ‘Röntgen rays,’ and showed that for screen observation, where a steady illumination is desired, the steady discharge from one of his eight-plate influence machines was preferable to the intermittent discharge of the usual induction coil. His machines are also used in hospitals for the production of powerful brush discharges, efficacious in the treatment of lupus and cancer.
Wimshurst also invented an improved vacuum pump, an improved method for electrically connecting light-ships with the shore station, and an instrument for ascertaining the stability of vessels. He was elected F.R.S. in 1898. He was also a member of the Institute of Electrical Engineers, the Physical Society, the
