Mary Watson Whitney was born on September 11, 1847 in Waltham, Massachussets, the daughter of Samuel Buttrick and Mary Watson (Crehore) Whitney. Her family was of old New England stock, going back on her father's side directly to John Whitney who brought his family to the New World in 1635. Her parents, who had intellectual tastes, gave their children a happy home and provided them with excellent educational advantages.
Mary attended the public schools of Waltham and early attracted the attention of her teachers by her unusual mental ability and love of study, being especially proficient in mathematics. Unfortunately further training seemed impossible to her since none of the eastern colleges were open to women, but while still in high school she heard of the new college intended especially for women being established in the Hudson Valley by Matthew Vassar. Her earnest desire to go there was gratified by her father, and accompanied by him she presented herself at Vassar College on its opening day in September 1865. She was at once greatly attracted by Prof. Maria Mitchell, the distinguished astronomer whose classes she entered. Her superiority and interest endeared her to the older woman and she became one of her most cherished pupils. She graduated in 1868, in the second class. Mary Whitney was much admired by her fellow students and recognized as a leader. Several times she served as president of their newly formed organizations. Her fine presence, good judgment and impartiality made her an excellent presiding officer, while her modesty and kindness of heart won their devoted affection. After graduation she continued her studies at home, and received the A. M. degree from Vassar in 1872.
By personal invitation she attended mathematical lectures given by Prof. Benjamin Peirce at Harvard College, and from 1874 to 1876 she attended lectures in mathematics at Zürich, Switzerland. Occasionally she returned to Vassar to assist Professor Mitchell in some piece of astronomical research, and in 1881 accepted an urgent call to become her permanent assistant. She kept this position until Professor Mitchell resigned in 1888, when she was appointed her successor. She was the director of the Vassar Observatory as well as professor of astronomy. In the former capacity she carried on research work with excellent equipment. She summoned to her assistance one of her own pupils and, working together, they published a long series of positions of comets and asteroids. Later they took up the study of variable stars and the measurement of photographic plates. In all, one hundred publications issued from the Vassar Observatory during her tenure of office which lasted until 1910 when a serious illness forced her retirement.
Her research work was marked by accuracy and thoroughness. As a teacher she was noted for her clearness in explaining difficult mathematical points and for the vividness and elegance with which she presented the more descriptive topics. Many students elected her courses merely to come in contact with her personality. As a member of the faculty, she was highly esteemed for her soundness of judgment and her progressive ideas. As a scholar she was a constant stimulus to her younger colleagues.
She was a fellow of the American Academy for the Advancement of Science.
She read extensively on political and philosophical topics, and had highly developed tastes in literature and music.
