Exum Percival Lewis

Background

Exum Percival Lewis was born on September 15, 1863, United States in Edgecombe County, North Carolina, the son of Henry Exum Lewis, a physician, and Emma (Haughton) Lewis.

Education

Educational facilities were meager in the rural community in which the Lewis family was settled. Privations that arose from the Civil War and the untimely death of his father when Lewis was only seven prevented his attending any elementary school whatever. His early education was obtained almost entirely by his own efforts, through reading and association with a country clergyman who gave him the freedom of his library. Later he attended night classes at Columbian University (the present George Washington University) and received the degree of B. S. in 1888. Three years later he entered Johns Hopkins University as a graduate student in physics. There he came in contact with Professor H. A. Rowland, the famous spectroscopist. Rowland was an inspiring teacher; his enthusiasm and idealism were a strong influence in Lewis' career, for he, too, adopted the study of spectroscopy as his life work. In 1895 he received the degree of Ph. D. from Johns Hopkins University.

Career

When Lewis was yet a boy he went to West Chester, Pennsylvania, where he worked as a printer's apprentice. His service in this office stood him in good stead. No doubt it contributed greatly to his accuracy in spelling and his ability to read rapidly--habits that were valuable assets to him in the occupation he eventually adopted.

His scientific training began a few years later when, as a young man, he accepted a position as clerk in the War Department, in Washington, D. C. In 1895 he went to the University of California as instructor in physics. Promotion to the grade of assistant professor came the following year, partly because a physicist was desired who could cooperate with the Lick Observatory in the field of astrophysics and spectroscopy. The period 1898-1900 Lewis spent abroad, as Whiting fellow, at the Physical Institute of the University of Berlin. He then returned to the University of California, where he became successively associate professor of physics (1902), professor (1908), and chairman of the department (1918); the last two positions he held until his death.

He was a member of expeditions to observe the eclipse of the sun in the South Seas, 1908, at Goldendale, Washington, June 1918, and at Ensenada, Lower California, in 1923. His chief studies in this connection were of the flash and the coronal spectrum. Although Lewis published no books, he was the author of papers on many diverse subjects, in the Astrophysical Journal and other scientific periodicals, and at the time of his death was working on the manuscript of a textbook of spectroscopy.

During his residence in Berlin he made the first systematic investigation of the influence of small quantities of a foreign substance on the character of the spectra of hydrogen, oxygen, and nitrogen. While he was engaged in studying the latter gas, he discovered a peculiar fluorescent afterglow that persists in the nitrogen discharge tube when a trace of oxygen or water vapor is present. Lord Rayleigh, inspired by these observations, discovered the chemical substance he termed "active nitrogen, " which, he showed, was capable of exciting fluorescence in other vapors than oxygen or water. Lewis investigated the band spectra of many substances. He was a pioneer in the very difficult fields of infra-red and far ultra-violet spectroscopy.

He studied the continuous spectrum of hydrogen in the Schuman region, its intensity and extent, and the conditions most favorable to its appearance. He measured the wave-lengths of several hundred new lines in the ultra-violet spectra of the rare gases krypton and xenon. Among his extensive researches in fields other than spectroscopy, were his investigations of ionization and electrical conductivity of gases. He devised a most ingenious method of determining the amplitude of sound waves by observation of illuminated ultra-microscopic particles set into forced vibration by the waves. He also studied various phenomena accompanying magnetic hysteresis.

He died in Oakland and was buried in the family plot in Sonoma, California.

Achievements

• Lewis was distinguished for his investigations in the field of physics and astrophysics. He had many achievements, the more important ones were related to the spectra of gases under various conditions of excitation, purity, etc. He contributed a number of articles on various topics to scientific and educational magazines. He also took the prominent part in the work of Astronomical Society of the Pacific.

Works

More photos

• book

  • Notes on the Properties of Matter and Heat

    (Unlike some other reproductions of classic texts (1) We h...)

  • A Text-Book of Physics

    (This book was originally published prior to 1923, and rep...)

  • The Effects of a Magnetic Field On Radiation: Memoirs by Faraday, Kerr, and Zeeman; Volume 8

    ( This work has been selected by scholars as being cultur...)

  • Light, Magnetism and Electricity

Politics

He was an early advocate of equal suffrage and was generous in support of projects for the improvement of political conditions.

Personality

He possessed a rare ability to divest a complex subject of its difficulty. His lectures on spectroscopy were models of clarity. An idealist and a philosopher, he was distinguished by great simplicity of character and singleness of purpose. His devotion to the study of scientific truth made him uncompromising in dealing with civic or political questions.

Connections

In 1901 Lewis was married to Louise Sheppard of San Francisco. They had two children--a son and a daughter.

Father:

Henry Exum Lewis

physician

Mother:

Emma (Haughton) Lewis

Spouse:

Louise Sheppard

References

• Bible Records of Early Edgecombe North Carolina
• Tombstone and Census Records of Early Edgecombe