May 17, 1860 - March 27, 1934
Charlotte Cynthia Barnum was born in Phillipston, Massachusetts, the daughter of the Reverand Samuel Weed Barnum and Charlotte Betts Barnum. Her early education was by private study and her preparation for college was at the Hillhouse School in New Haven. She graduated from Vassar College in 1881. After various teaching positions at Bett's Academy (Stamford, Connecticut), Hillhouse School, and Smith College, where she taught astronomy, Barnum returned to study mathematics, astronomy, and physics at John Hopkins University from 1890 until 1892. In 1892 she moved to Yale University, where her father had studied, and in 1895 she became the first of three women to receive Ph.D.'s in mathematics from Yale before 1900. Her dissertation was on "Functions Having Lines or Surfaces of Discontinuity." Barnun joined the American Mathematical Society in 1894, the first year of the Society's existence after its change in name from the New York Mathematical Society.
After receiving her Ph.D., Barnum taught mathematics for one year at Carleton College. Between 1898 and 1913, she held various jobs in the insurance industry as an actuary, at the U.S. Naval Observatory, the U.S. Coast and Geodesic Survey, and with the U.S. Department of Agriculture as an editor for the Biological Survey. In some publications it is reported that Barnum did editorial work for the Yale Peruvian Expedition and after that worked as a proofreader for the scientific publications at Yale University. There is no mention of her as an employee at Yale in their personnel records; she may have worked as a volunteer. Between 1921 and 1923 she returned to teaching mathematics at Scovill and Columbia Preparatory schools in New York and then at Walnut Hill, Natick, Massachusetts. In the fifth edition of American Men and Women of Science, she listed her research interests as functions having lines or surfaces of discontinuity, tides and currents, annuities, and social legislation.