Theodore Lyman (23.02.1874- 11.09.1954) was an American experimental physicist and a member of the National Academy of Sciences. He was born in Boston. He graduated from Harvard University (1897) and worked there from 1902; in 1910-47 he was director of the Jefferson Physical Laboratory and in 1917 — 25 professor.
His research concerned optics and spectroscopy. In 1906 he discovered a spectral series in the ultraviolet part of the hydrogen spectrum (the Lyman series). He obtained the ultraviolet spectra of gases and of metallic sparks down to 500 Å. In 1906 he established standards in the ultraviolet region of the spectrum and was the first to measure wavelengths in the vacuum ultraviolet region. He proposed a double-slit vacuum spectrograph (the Lyman spectrograph).
He was president of the American Physical Society (1921) and of the American Academy of Arts and Sciences (1924). The B. Rumford Medal and others.