Scientist. An astrophysicist, he was the fifth Secretary of the Smithsonian Institution in Washington, DC. He was also the second and last person to hold both posts of Secretary of the Institution and Director of the Smithsonian Astrophysical Observatory at the same time. His studies of how solar activity affects weather patterns on Earth were the forerunner of long-range weather predictions. Born in Wilton, New Hampshire, the son of a farmer and the youngest of four children, he attended public schools and graduated from Phillips Andover Academy. In 1894, he graduated with a BS degree from the Massachusetts Institute of Technology (MIT) with a major in Chemical Physics. Remaining at MIT, he earned a Master of Science (MS) degree in 1895. Coming to the attention of Samuel Pierpont Langley, he was hired in 1895 as an assistant at the Smithsonian's Astrophysical Observatory, where he helped Langley map the infrared spectrum of the sun and develop other means of measuring wavelengths in the infrared region of the solar spectrum. Under Langley, Abbot flourished as a creative designer and builder of scientific instruments for measuring solar radiation. He was a leader in the Smithsonian's expeditions to observe solar eclipses in 1900 and 1901, proving to be a reliable observer. Langley's intention was to show that by understanding the amount and character of solar radiation upon the Earth's surface, man could plan to use this information for controlling agriculture and other uses. Abbot picked up the scientific mission of showing that Earth's meteorology and biology were intimately connected to variations in the sun's energy output. In 1907, following Langley's death the previous year, he was made the second Director of the Smithsonian's Astrophysical Observatory. In 1910, he was awarded the prestigious Draper Gold Medal by the National Academy of Sciences, and in 1916, he was awarded the Rumford Medal from the American Academy of Arts and Sciences. By the mid-1920s, he had proven the connection between solar cycles and their effects on weather patterns on Earth. In 1930, he was made the fifth Secretary of the Smithsonian Institution while keeping his job as Director of the Astrophysical Observatory. In 1944, Abbot retired from both jobs.