Sir Charles Vernon Boys, F.R..S., Hon.F.R.S.E.

by C T R Wilson

Charles Vernon Boys was born at Wing, in the county of Rutland, on March 15, 1855, the son of the Rev. Charles Boys. After being at school at Marlborough, he was a student at the Royal School of Mines from 1873 till 1876. He was for a short time at a colliery, but was brought back to South Kensington by Guthrie, who made him his private assistant and gave him a life membership of the Physical Society. For many years he was Demonstrator and Librarian of that Society; he was later to become its President, and was its second Duddell Medallist. Boys was Demonstrator of Physics at the Royal College of Science, South Kensington, from 1881 till 1889, when he became Assistant Professor.

Much of the work for which Boys is best known was begun in the years 1887-90. A preliminary note on the radio-micrometer was communicated to the Royal Society on February 24, 1887. In the tests of the method there described he had used spun glass for the suspension of his radio-micrometer. In a note added a month later he states that he has since found a method of producing fibres immensely superior to those of spun glass. These fibres, of fused quartz, were obtained by his bow-and-arrow method, and their production, properties, and some of their uses were described in a paper read before the Physical Society a little later in the same year. An account of the perfected radio-micrometer was given to the Royal Society in the following year. He found a suitable application for the instrument in an investigation "on the heat of the moon and stars," begun, in his father's garden at Wing, in September 1888, and published in the Proceedings of the Royal Society two years later. Boys found his apparatus amply sensitive for the comparison of the heat received from different parts of the moon's surface; it gave no certain indication of any heat being received from even the brightest stars, although able to detect the heat received from a candle-flame more than a mile away.

In 1889 Boys communicated to the Royal Society his ideas on improvements in the Cavendish experiment to determine the constant of gravitation, pointing out the advantages of reducing the scale of the apparatus; the use of a fibre of fused quartz for the suspension made it practicable to carry this reduction very much further than would otherwise have been possible. Boys's final measurements of the Newtonian constant of gravitation were carried out in the Clarendon Laboratory, Oxford, and published by the Royal Society in 1894. He had succeeded in reducing the length of the torsion rod from which the attracted masses were suspended from the six feet of the original Cavendish experiment to less than one inch; the measurement was more accurate than any previously made of the constant of gravitation.

In 1890 Boys published a paper on quartz as an insulator. His experiments not only demonstrated the great merits of quartz as an insulator of electricity, but gave very strong indications that the leakage of electricity from a charged body suspended in a closed vessel may not be entirely by the insulating support but partly by conduction through the air.

An account of experiments with a soap bubble was given by Boys to the Physical Society in 1888, and in December 1889 and January 1890 he delivered the Christmas lectures before a juvenile audience at the Royal Institution, which formed the basis of his book on Soap Bubbles and the Forces which Mould them. In this subject Boys found ample scope for the exercise of his wonderful ingenuity and manual dexterity.

Notes on photographs of rapidly moving objects and on the oscillating electric spark formed the subject of a communication to the Physical Society in 1890. He gave a popular lecture at the Edinburgh meeting of the British Association in 1893, in which he showed photographs of rifle bullets in flight and the air waves accompanying them. In a note communicated in 1937 to the Royal Society of Edinburgh, of which in 1936 he had been elected an Honorary Fellow, he draws attention to the high speed of rotation given to a mirror by very simple means in these early experiments. He had used the rotating mirror to measure times as short as one-hundred millionth of a second, and with its aid had found how to get an illuminating spark which lasted for only one-thirteen millionth of a second.

It was in 1888, in the midst of this wonderfully active period of his scientific life, that Boys was elected a Fellow of the Royal Society; he was awarded a Royal Medal in 1896 and the Rumford Medal in 1924.

In 1897 Boys became one of the metropolitan Gas Referees. He greatly improved the methods of gas calorimetry, and the calorimeter described by him in the Proceedings of the Royal Society in 1903 was adopted as the standard instrument for testing London gas; it came into general use in gasworks throughout the country. He devoted much thought during many years to the planning of a still better gas calorimeter, but it was not till 1934 that he finally arrived at a design which completely satisfied him. This was described in his Guthrie Lecture of that year. Boys told in this lecture how the idea underlying one important part of the design came to him in a dream. "I was sufficiently impressed by it to get up at six and go to Victoria Street, where I blew in glass the bulb and tube you now see." He was then in his eightieth year.

it is not surprising that Boys, after his experiments with electric spark discharges, should take an interest in the development of a lightning discharge. With the object of investigating this subject (of finding, for example, at what part of its path the discharge begins and the speed with which it extends itself) he constructed in 1900 a camera with a rotating pair of lenses, of which he gave a short description in Nature in 1926. Although he was in the habit of carrying this camera about with him, it was not till twenty-eight years after its construction that, while staying with Loomis in America, he succeeded in getting a photograph which showed the progressive development of a lightning discharge. Boys must have been interested in lightning for more than half a century when this photograph was taken, for in 1926 he gave in Nature a very interesting account of a distant thunder-cloud which he had watched from Wing in 1876. For every flash seen in the rain-cloud or below, and simultaneously with it, one or more slender flashes of typical lightning (in one case as many as seven) were observed to shoot upwards into the clear sky.

In spite of the handicap of the loss of one eye and very defective vision in the other, Boys continued his varied activities till the end of his long life. When he was eighty he published little books on the natural logarithm and on weeds; it was in this year that he received his Knighthood. In his eighty-ninth year he published a paper on " An Elliptograph"; problems in practical mathematics had always interested him.

Boys does not appear to have been greatly interested in theoretical Physics; his delight was in designing, constructing, and manipulating apparatus for physical measurements of the highest accuracy and in overcoming experimental difficulties which to most would have seemed insuperable. He was a really great experimenter, and his methods of working were original and often unconventional.

He appears to have been equally original and unconventional in ordinary life.

Boys married in 1892 Marion Amelia, daughter of the late Henry Pollock; the marriage was dissolved eighteen years later. They had one son and one daughter.

Boys died on March 30, 1944, in his ninetieth year.

Charles Vernon Boys's RSE obituary by C T R Wilson appeared in Royal Society of Edinburgh Year Book 1945, 14-15.

See also Obituary Notices of Fellows of the Royal Society, IV, 1944, 771.