In 1875, she submitted a model sculpture of Charles Sumner for a blind competition conducted by the Boston Art Committee. She knew Sumner, a senator and abolitionist, through her brother Alexander, who was a classmate of Sumner's at Harvard University. Whitney's model competently captured Sumner's frame and features. She depicted him seated in a chair, in part because of ancient Greek artist's practice of portraying prominent people seated to "represent dignity and something of state." She won the contest, including receiving the prize money, until the judges realized that they had selected a work made by a woman; they thought it would be inappropriate for a woman to sculpt a man's legs. The judges rejected her offering and selected Thomas Ball's sculpture for the Boston Public Garden. Both the Sumners and the Whitneys were disappointed, but Whitney wrote in a letter, "Bury your grievance; it will take more than the Boston Art committee to quench me."