ALEXANDER, Stephen, astronomer, born in Schenectady, New York, 1 September 1806; died in Princeton, New Jersey, 25 June 1883. He was graduated at Union in 1824 and at Princeton Theological Seminary in 1832, was a tutor at Princeton in 1833, and became adjunct professor of mathematics in 1834, and professor of astronomy in 1840. From 1845 to 1854 he occupied the chair of mathematics, and afterward that of astronomy and mechanics until he retired in 1878. He has written a great number of scientific papers, some of which have been translated into other languages. He was chief of the expedition that went to the coast of Labrador to observe the solar eclipse of 18 July 1860, and was the leader also of that sent to the west to observe the eclipse of August 1869. His principal writings are "Physical Phenomena attendant upon Solar Eclipses," read before the American philosophical society in 1848- a paper on the "Fundamental Principles of Mathematics," read before the American Association for the Advancement of Science in 1848; another on the "Origin of the Forms and the Present Condition of some of the Clusters of Stars and several of the Nebulm," read before the American Association in 1850; others on the "Form and Equatorial Diameter of the Asteroid Planets" and Harmonies in the Arrangement of the Solar System which seem to be Confirmatory of the Nebular Hypothesis of Laplace," presented to the National Academy of Science ; a "Statement and Exposition of Certain Harmonies of the Solar System," which was published by the Smithsonian Institute in 1875.