1365. CHARLES GREELEY ABBOTT (1872-1973) American astrophysicist and director of the Smithsonian Astrophysical Observatory for almost four decades, campaigning to demonstrate that varying output of energy by the Sun has a measurable effect on the Earth's weather. Very rare A.N.S. 1p. 12mo., [n.p., n.d.], with fine content, in full: "Recalling with pleasure my two visits to South America, especially my grand view of the total solar eclipse of 1919 at La Paz Bolivia, I am Very sincerely yours, Charles Greeley Abbot". Edges ragged, with an affixed photo cut from a newspaper above, fine condition. With envelope panel, cancelled Oct. 31, 1924, also in Abbot's hand addressed to a Mr. San Martin in Uruguay. $75-100