AVE8907274: 1960s: Man blows on embers in cannister and stirs them with stick. Flames emerge from cannister. / Bridgeman Images

AVE8907277: 1960s: Men point guns at horsemen near log cabin in painting. / Bridgeman Images

AVE8907282: 1960s: Photographic portrait of man in suit and tie sits on display. / Bridgeman Images

AVE8907283: 1960s: Photographic portrait of man in suit and tie sits on display. / Bridgeman Images

AVE8907284: 1960s: Photographic portrait of Daniel Webster sits on display. / Bridgeman Images

AVE8907302: 1960s: Government officials meet in House of Representatives in painted illustration. / Bridgeman Images

AVE8907308: 1960s: Men work in steel mill in painted illustration. UPSIDE DOWN / Bridgeman Images

AVE8907309: 1960s: Portraits of Abraham Lincoln and Hannibal Hamlin appear in painted illustration. UPSIDE DOWN / Bridgeman Images

AVE8907314: 1960s: Scale. Man points at white balls in upside down test tube. Man lights candle. / Bridgeman Images

AVE8907315: 1960s: Scale. Finger points at weights. Finger points at test tube filled with white balls and candle. / Bridgeman Images

AVE8907322: 1960s: Hot piece of coal over bunsen burner. / Bridgeman Images

AVE8907331: 1960s: Yard. Boys get on seesaw and rock up and down. Boy watches. / Bridgeman Images

AVE8907336: 1960s: House. Yard. Boys play on seesaw. Man picks up piece of wood. / Bridgeman Images

AVE8907337: 1960s: Man uses push lawn mower to cut grass. / Bridgeman Images

AVE8907352: 1960s: Shadow of object on chart. / Bridgeman Images

AVE8907361: 1960s: Pocket watch. Man turns watch to show interior mechanism. Part spins. / Bridgeman Images

AVE8907367: 1960s: Copper bowl floats in bowl of water. Woman lifts and replaces bowl. Woman points. / Bridgeman Images

AVE8907372: 1960s: Sundial. / Bridgeman Images

AVE8907373: 1960s: Sundial. / Bridgeman Images

AVE8907375: 1960s: Clock. / Bridgeman Images

AVE8907385: 1960s: Sand falls through hourglass. Man turns hourglass over. / Bridgeman Images

AVE8907393: 1960s: Sunset over water, tilt down to reflection on water. / Bridgeman Images

AVE8907397: 1960s: Photograph of man. / Bridgeman Images

AVE8907402: 1960s: View across the cover of Harper's Weekly on January 5, 1861. / Bridgeman Images

AVE8906503: 1960s: Man with weight on scale, balancing scale. / Bridgeman Images

AVE8906504: 1960s: Sculpture of woman and child. / Bridgeman Images

AVE8906511: 1960s: Sculpture of woman and child. / Bridgeman Images

AVE8906515: 1960s: People look at marble sculptures on display in gallery. / Bridgeman Images

AVE8906526: 1960s: Men ride train engine pulling cargo through rail yard. Worker sweeps tracks clean near signal light. / Bridgeman Images

AVE8906535: 1960s: Sculpture on display in gallery. / Bridgeman Images

AVE8906539: 1960s: Statue of eagle stands outside large brick post office building. / Bridgeman Images

AVE8906549: 1960s: Sculpture on display in gallery. / Bridgeman Images

AVE8906559: 1960s: Metal medallion hangs from bottom of medieval parchment. / Bridgeman Images

AVE8906561: 1960s: Sculpture on display in gallery. / Bridgeman Images

AVE8906565: 1960s: Sculpture on display in gallery. / Bridgeman Images

AVE8906567: 1960s: Large nest hangs in trees above marsh. / Bridgeman Images