Alexander Dallas Bache (July 19, 1806 - February 17, 1867) was an American physicist, scientist and surveyor who erected coastal fortifications and conducted a detailed survey mapping of the United States coastline. As a lieutenant in the United States Army Corps of Engineers, he was engaged for a short time in the erection of coastal fortifications. In 1843 Bache was appointed superintendent of the United States Coast Survey. He convinced the United States Congress of the value of this work and by means of the liberal aid it granted, he completed the mapping out of the whole coast by a skillful division of labor and the erection of numerous observing stations. In addition, magnetic and meteorological data was collected. Bache served has head of the Coast Survey for 24 years until his death in 1867 at the age of 60.