1820-1912 1858-1952 1886-1957 20thcentury adolph americanainart artistic barns biography buckscounty charles criticismandinterpretation criticismandinterpretationsheeler diego diplomats exhibitions ferdinandludwig ferdinandpeter georgebailey greatbritain herff historians history homesandhauntssheeler inart machineryinart modernism(art) pennsylvania photography physicians pictorialworks precisionism rivera sansom sheeler unitedstates vonherff