151 years ago today, November 23, 1874 (October 15, 1874 in the lunar calendar), American physicist Theodore Ryman was born. November 23, 1874-Theodore Ryman was born. American physicist Ryman was born in Boston, Massachusetts, USA in 1874. In 1893, he entered Harvard University to study physics. After graduating in 1897, he stayed on to teach. In 1919, he went to work in the Cavendish Laboratory at the University of Cambridge in the United Kingdom for two years, and returned to Harvard University in 1921 to serve as a professor. Since 1926, Ryman has served as director of the Jefferson Physics Laboratory and is a member of the American Academy of Sciences. He died in Boston in 1954 at the age of 80. During his research career, Ryman devoted himself to the study of far-ultraviolet spectroscopy and developed a vacuum spectrograph capable of measuring spectral lines with wavelengths shorter than 200nm. In 1906, Lyman and Millikan collaborated and discovered the Lyman line system in the far ultraviolet region of the hydrogen atom spectrum, improving the research on hydrogen atom spectrum and confirming the correctness of the principles of combination of Rydberg's formula, Bohr's model and Ritz spectral terms. Since then, Lyman observed the spectra of neon, helium, aluminum, magnesium and other elements, and studied the short-wave components in the solar spectrum, but did not obtain satisfactory results. Later, in 1959, after his death, instruments carried by rockets observed the Lyman alpha line in the solar spectrum. In addition, Ryman has also studied the sterilization effect of ultraviolet light. Comments: Discoverer of the Lyman series in the hydrogen atom spectrum.