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HE same restless energy which impelled the American people to become a world-power has led their men of science to extend the range of their researches. The possibilities of a nation's influence are bounded only by the whole earth; and in a similar way the field of astronomy is limited only by the whole sky. At the latitude of Cambridge, Mass., an observer can never see more than three fourths of the sky. In order to observe the remaining fourth, which lies about the south pole of the heavens, he must seek some station below the equator. A complete study of all the stars in the sky is imperatively demanded for the solution of many of the great questions which the astronomy of the future must answer. Only by bringing such completeness into astronomical research will the construction of the universe and the true place of our solar system become known.

The Arequipa Station of the Harvard College Observatory owes its foundation to the far-sighted policy of its present director. Professor Edward C. Pickering. Under his direction, in 1889, the writer of this article visited South America in order to make the preliminary studies necessary to the selection of a station for the observation of the southern sky. The west coast of South America was chosen for this purpose, since it offered the possibility of great altitude, in addition to a dry climate and a clear atmosphere. The funds for this enterprise had been bequeathed for such a purpose by Uriah A. Boyden, a Boston engineer.

From the best information which could be obtained in the United States, it was thought that the valley of the River Rimac, near Lima, Peru, would furnish conditions favorable for the proposed station. The valley itself, however, did not offer a sufficiently free horizon, being shut in everywhere by mountains. There was a wide range for choice in regard to elevation. The hills near Lima are only a few hundred feet in height, while the great mountains forming the western Andes rise eighteen thousand feet above sea level. The primary conditions were an open horizon and a clear sky. To obtain a free horizon it was only necessary to climb one of the steep and barren summits near the valley; but to determine where the sky was clearest was a more difficult problem. At this latitude the western Cordillera extends