Personal and business correspondence, patents, financial papers, blueprints and drawings, scrapbooks of newspaper clippings, and other material relating to: Herman Hollerith's tabulating machines and their use in census taking; the operation of the Tabulating Machine Company and its merger with the Computing-Tabulating-Recording Company; and Hollerith's later association with this company and International Business Machines. Other topics include the employment of Charles G. Talcott, Sr., as a civil engineer in the construction of the railway from Vera Cruz to Mexico City, Mexico, the 1877 fire at the U. S. Patent Office, and the 1906 San Francisco earthquake and fire. Correspondents include C. L. Hayes, Philip P. Merrill, Samuel G. Metcalf, and the Frisbie Motor Company.