U.S. surgeon and transit expert who played a major role in the development of rapid transit in New York City.

Gilbert attended the College of Physicians and Surgeons in New York City and then served as a surgeon in the Federal Army in the Civil War, attaining the rank of lieutenant colonel. He became interested in rapid transit as a means of freeing people from living in the unhealthful, crowded tenements in the centres of large cities. After gaining experience as assistant superintendent of the Central Railroad of New Jersey, he incorporated the Gilbert Electric Railway Company on June 17, 1872, to build elevated lines in New York City. The cars were to be propelled by air pressure from pneumatic tubes mounted on the elevated structure. A financial depression delayed construction until 1876, however, and forced adoption of the more conventional type of elevated railroad, which employed trains drawn by steam locomotives. The Sixth Avenue line, running from Trinity Church to Central Park, was completed and began operation in April 1878, but financiers forced Gilbert from the company.