John William Strutt | Biography

In 1873 John William Strutt's father, the second Baron Rayleigh, died and Strutt succeeded to that title. He is, therefore, almost universally referred to in the scientific literature as Lord Rayleigh. While the majority of his work dealt with sound and optics, Rayleigh may be most familiar to the layperson as the discover of the rare gas argon. For this accomplishment he was awarded the 1904 Nobel Prize in physics. Rayleigh served for a period of five years as director of the Cavendish Laboratory at Cambridge University. With that exception, he spent nearly all of his adult life at his home in Terling Place where he constructed a well-equipped scientific laboratory. There he carried out experiments on a remarkable variety of subjects that led to the publication of some 450 papers.

John William Strutt was born at Langford Grove, near Maldon, in Essex, on November 12, 1842. He was the eldest son of John James Strutt, second Baron Rayleigh, and the former Clara Elizabeth Vicars. Strutt's health as a child was not very good, and he was unable to remain at school for very long. He attended Eton and Harrow for about one term each and spent three years at a private school in Wimbledon. Finally, in 1857, his education was entrusted to a private tutor, the Reverend George Townsend Warner, with whom he stayed for four years.

In 1861 Strutt entered Trinity College, Cambridge, where he studied mathematics under the famous teacher E. J. Routh. During his four years at Trinity, Strutt went from being a student of only adequate skills to one who captured major prizes at graduation. One examiner is reported to have said that Strutt's answers were better than those found in books.

Following graduation, Strutt was elected a fellow of Trinity College, a position he held until 1871. In 1868 he took off on the extended "Grand Tour" vacation traditional among upper class Englishmen, except that he chose to visit the post-Civil War United States rather than the continent of Europe. In 1871, at the conclusion of his tenure at Trinity, Strutt was married to Evelyn Balfour, sister of Arthur James Balfour, later to be prime minister of Great Britain in 1902. The Strutts had three sons, Robert John, Arthur Charles, and Julian.

Within a few months of his marriage, Strutt became seriously ill with a bout of rheumatic fever. As his health returned, he decided to make a recuperative visit to Egypt and Greece with his young bride. It was on a trip down the Nile during this vacation that he began the scientific work that was to occupy his attention for most of the rest of his life, a massive work on The Theory of Sound.

Shortly after the Strutts returned to England in the spring of 1873, his father died and Strutt succeeded to the hereditary title of Baron Rayleigh. He also took up residence in the family mansion at Terling Place, Witham, where he was to live for most of the rest of his life. He soon constructed a modest, but well-equipped, laboratory in which he was to carry out experiments for the next forty years. At first he divided his time between the laboratory and the many chores associated with the maintenance of the Rayleigh estate. Gradually he spent less time on the latter, and after 1876 he left the management of his properties to his younger brother Edward.

Rayleigh always seemed to be a man of unlimited interests. The two fields to which he devoted the greatest amount of time, however, were sound and optics. In 1871, for example, he derived a formula expressing the relationship between the wavelength of light and the scattering of that light produced by small particles, a relationship now known as Rayleigh scattering. One of his first projects in his new Terling laboratory was a study of diffraction gratings and their use in spectroscopes (instruments with which scientists may study the electromagnetic spectrum). Rayleigh appeared to be totally satisfied with his life and work at Terling Place. Then, in 1879, James Clerk Maxwell, the first Cavendish Professor of Experimental Physics at Cambridge, died. The post was offered first to Sir William Thomson, who declined, and then to Lord Rayleigh. With considerable reluctance, he accepted the appointment with the understanding that he would remain for only a limited period of time. During his tenure at Cambridge, Rayleigh made a number of changes that placed the young Cavendish Laboratory on a firm footing and prepared it for the period of unmatched excellence that was to follow in succeeding decades. The most important experimental work carried out under his auspices was a reevaluation of three electrical standards, the volt, ampere, and ohm. This work was so carefully done that its results remained valid until relatively recently.

In 1884 Rayleigh resigned his post at Cambridge and returned to his work at Terling Place. Over the next decade he took on an even more diverse set of topics, including studies of electromagnetism, mechanics, capillarity, and thermodynamics. One of his major accomplishments during this period was the development of a law describing radiation from a black body, a law later known as the Rayleigh-Jeans law.

At the end of the 1880s, Rayleigh began work on the problem for which he is perhaps best known, his discovery of the inert gas argon . That work originated as a by-product of Rayleigh's interest in Prout's hypothesis. In 1815 the English chemist William Prout had argued that all elements are made of some combination of hydrogen atoms. An obvious test of this hypothesis is to find out if the atomic weights of the elements are exact multiples of the atomic weight of hydrogen.

By 1890 most scientists were convinced that Prout's hypothesis was not valid. Still, Rayleigh was interested in examining the problem one more time. In so doing, he made an unexpected discovery, namely that the atomic weight of nitrogen varied significantly depending on the source from which it was obtained. The clue that Rayleigh needed to solve this puzzle was a report that had been written by the English chemist Henry Cavendish in 1795. Cavendish had found that whenever he removed oxygen and nitrogen from a sample of air, there always remained a small bubble of some unknown gas.

To Rayleigh, Cavendish's results suggested a reason for his own discovery that the atomic weight of nitrogen depends on the source from which it comes. Nitrogen taken from air, he said, may include a small amount of the unknown gas that Cavendish had described, while nitrogen obtained from ammonia would not include that gas. Still, Rayleigh was not entirely sure how to resolve this issue. As a result, he wrote a short note to Nature in 1892 asking for ideas about how to solve the nitrogen puzzle.

The answer to that note came from William Ramsay, who was working on the same problem at about the same time. Eventually, the two scientists, working independently, obtained an answer to the problem of the mysterious gas. They discovered that Cavendish's "tiny bubble" was actually a previously unknown element, an inert gas to which they gave the name argon, from the Greek argos, for "inert." On January 31, 1895, Rayleigh and Ramsay published a joint paper in the Philosophical Transactions of the Royal Society announcing their discovery of argon . A decade later, in 1904, Rayleigh was given the Nobel Prize in physics and Ramsay the Nobel Prize in chemistry for this discovery.

Even after returning to Terling Place in 1884, Rayleigh remained active in a number of professional positions. He was appointed professor of natural philosophy at the Royal Institute in 1887 and gave more than a hundred popular lectures there over the next fifteen years. In 1885 he became secretary of the Royal Society, a post he held until his election as president of the organization in 1905. When he left that post in 1908, he became chancellor of Cambridge University, a position he held until his death at Terling Place on June 30, 1919.

In addition to the 1904 Nobel Prize, Rayleigh received the Royal Medal of the Royal Society in 1882, Italy's Bressa Prize in 1891, the Smithsonian Institution's Hodgkins Prize in 1895, Italy's Matteuci Medal in 1895, the Faraday Medal of the Chemical Society in 1895, the Copley Medal of the Royal Society in 1899, the Rumford Medal of the Royal Society in 1914, and the Elliott Cresson Medal of the Franklin Institute in 1914.