The last of the great American astronomers whom we shall mention here is Edward Charles Pickering, whose name is so closely connected with the development of the great observatory at Harvard. Born at Boston, and educated at the Lawrence Scientific School, his first work was in the field of physics, but in 1876, he was appointed professor of astronomy and geodesy, and director of the Harvard observatory, which, under his management, has become of the first importance. His principal work has been the determination of the relative brightness of the stars, and many thousands have been charted. On the death of Henry Draper, the study of the spectra of the stars by means of photography was continued as a memorial to that great scientist, and the results obtained have been of the most important character, including a star map of the entire heavens. Other phases of the science of scarcely less importance have been carefully developed, and the work which has been done under Pickering's direction, is second to none in the history of the science. Not satisfied with the Northern hemisphere, a branch has been established in Peru, in which the observatory's methods of research have been extended to the south celestial pole. So for eighteen years and more, it has kept ceaseless watch of the heavens, with an accuracy of which the world has hardly a conception. For this great work the scientific world must pay tribute to the genius and perseverance of Edward Charles Pickering. The second department of science claiming our attention is that of paleontology. Here one of the most eminent of American names is that of Othniel Charles Marsh. A graduate of Yale and firmly grounded in zoology and kindred sciences by a course of study at Heidelberg and Berlin, he returned to the United States in 1866 to accept the chair of paleontology which had been established for him at Yale. The remainder of his life was devoted to the original investigation of extinct vertebrates, especially in the Rocky Mountain regions. In these explorations, more than a thousand new species of extinct vertebrates were brought to light, many of which possess great scientific interest, representing new orders never before discovered in America. So important was this work that the national geological survey undertook the publication of his reports, which formed the most remarkable contributions to the subject ever written in this country, attracting the attention and admiration of the whole scientific world.