University of Pennsylvania formally dedicated its observatory on a 100-acre farm bequeathed by Mr. Reese Wall Flower in 1897. Gustavus Wynne Cook, an avid amateur astronomer and wealthy Philadelphia businessman, established an observatory in his own home. When he moved to an estate in Wynnewood during the depression, he constructed two buildings to accommodate his hobby. When Mr. Cook died in 1940, he left all his astronomical instruments to the University of Pennsylvania. In the late 1940s, Charles P. Olivier, then Chairman of the Astronomy Department and Director of the Flower Observatory, urged the University administration to purchase a plot of land in Willistown Township, Chester County, bounded by Providence Road and Warren Avenue. In 1954, simultaneous with the completion of the new Physical Science Building (later called the David Rittenhouse Laboratory), an on-campus observatory was established on the rooftop of the building. In 1956, a new off-campus Flower and Cook Observatory was finally constructed with funds from the sale of the Flower Observatory property.