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Professional and personal files including Armstrong's correspondence with professional associations, other engineers, and friends, his research notes, circuit diagrams, lectures, articles, legal papers, and other related materials. Of his many inventions and developments, the most important are: 1) the regenerative or feedback circuit, 1912, the first amplified radio reception, 2) the superheterodyne circuit, 1918, the basis of modern radio and radar, 3) superregeneration, 1922, a very simple, high-power receiver now used in emergency mobile service, and 4) frequency modulation - FM, 1933, static-free radio reception of high fidelity. More than half the files concern his many lawsuits, primarily with Radio Corporation of America, over infringement of the Armstrong patents. Litigation continued until 1967. Other files deal with his work in the Marcellus Hartley Research Laboratory at Columbia University, 1913-1935, and with the American Expeditionary Forces in France during World War I, his Air Force contracts for communications development, Army research during World War II, the Radio Club of America, the Institute of Radio Engineers, FM development at his radio station at Alpine, N.J., the use of FM in television, his involvement in Federal Communications Commission hearings and legislation, and his work with the Zenith Radio Corporation. Also, letters to H.J. Round

This collection consists of glass plate negatives compiled by Columbiana curators and University Archives staff. It includes a color glass plate negative of a photograph of Nicholas Murray Butler.

Collection contains watercolor renderings, sketches, technical drawings (ground plans, elevations and details), photographs, glass plate and acetate negatives, scrapbooks, set models and some related papers covering Urban's career in Vienna and New York as an architect, set designer, decorator and illustrator. There is a thorough representation of his New York career including his set designs for Florenz Ziegfeld (1915-1932) and the Metropolitan Opera (1917-1933). The collection also contains information on Urban's work for William Randolph Hearst as art director for Cosmopolitan Studios, his exhibitions including his 1921 Wiener Werkstätte store, and his many architectural projects. Biographical information and research gathered by Richard Cole and Randolph Carter including contributions from his daughter,Gretl Urban, and biographical notes and some letters from his widow, Mary Urban, are also present.

808 glass-plate negatives and ten black-and-white telescopic photographic prints of astronomical subjects.

The papers include correspondence, subject files, photographs, and printed materials. The majority of the collection concerns the mission of the American Red Cross to Russia in 1917-1918; Thacher served as a secretary of the mission. There are letters and telegrams by W.B. Thompson and Raymond Robins, records of supplies, shipments, and distribution reports and over 600 photographs from Russia, China, and Romania. There is substantial correspondence from 1918-1919 concerning Russia, including letters by Louis Brandeis, Felix Frankfurter, and Lillian Wald. A substantial part of the collection concerns Russian war relief in 1941-1942, an area in which Thacher was active. Printed materials include a pamphlet and an article on Russia prepared by Thacher after his return from that country in early 1918.