Correspondence, manuscripts, typescripts, conference papers, scientific drawings, photographs, and printed material. This collection consists chiefly of Halford's manuscripts and typescripts of his writings for scientific journals and papers presented at various conferences and symposiums with related correspondence of colleagues. Also included are files on the teaching of chemistry with reference to practices at Columbia, photographs of his spectrometers, a copy of his patent for Recording Spectrometers, and a file relating to his participation in a 1959 panel discussion on the future of education sponsored by the Barnard College and Columbia Alumni Clubs of Chicago. The printed material includes reprints and accompanying bibliography of Halford's writings. Also, a photograph taken by Jack Aeby at the test site of the atomic bomb, Alamogordo, N.M., 16 July 1945 has been added to the collection.