In January 1844, nineteen-year-old Julius Hilgard sent a letter to A. D. Bache, director of the United States Coast Survey, pointing out errors in the formulas used by the Survey to determine geographical positions, and attached his own corrected formulas. The impressed Bache responded with a job offer for Hilgard with the Coast Survey. Hilgard rose rapidly through the ranks of the Survey and was soon leading expeditions in the lower Chesapeake Bay and along the coast of the Gulf of Mexico. After leaving the Survey briefly for a job in private industry, he returned at the outbreak of the Civil War. He soon found himself in charge of the Office of Coast Survey and was required also to assume more and more of the duties of the superintendent, who was incapacitated by illness. He remained de facto head of the Coast Survey until 1867. In 1872 he traveled to Europe, taking charge of the operations for the telegraphic determination of transatlantic longitude. He also served on the International Committee for Weights and Measures, contributing to the 1874 determination of a new standard meter. Hilgard served as inspector of standard weights and measures for the United States; in 1881 he became superintendent of the Coast Survey, a position he held for four years. Hilgard was a charter member of the National Academy of Sciences.