HAYDEN, FERDINAND VANDEVEER American geologist, was born at Westfield, Mass., on Sept. 7, 1829. He graduated from Oberlin college in 185o and from the Albany medical college in 1853, where he attracted the notice of Prof. James Hall, State geologist of New York, through whose influence he was induced to join in an exploration of Nebraska. In 1856 he was engaged under the U.S. Government, and commenced a series of investigations of the western Territories, one result of which was his Geological Report of the Exploration of the Yellowstone and Missouri Rivers in 1859-60 (1869). During the Civil War he was actively employed as an army surgeon. In 1867 he was appointed geologist-in-charge of the U.S. geological and geographi cal survey of the territories, and from his 1 2 years of labour there resulted a most valuable series of volumes in all branches of natural history and economic science; and he issued in 1877 his Geological and Geographical Atlas of Colorado. Upon the reorgan ization and establishment of the U.S. geological survey in 1879 he acted for seven years as one of the geologists. He died at Phila delphia on Dec. 22, 1887.