George A. Cornish, 87, retired editor in chief of the Encyclopedia Americana. Cornish began his career on newspapers, joining the old New York Herald-Tribune in 1923. He served as managing editor from 1941 to 1952 and as executive editor from 1952 to 1960. Cornish left the Herald-Tribune in 1960 to work at Grolier Inc., a publishing house, where he was editor in chief of Encyclopedia International. He took a similar job with Encyclopedia Americana in 1965 and retired in 1970. In St. Petersburg, Fla., on Sunday.