In our own country the heights of theoretical astronomy have been scaled by such minds as Benjamin Pierce, the profound mathematician of Harvard University; James C. Watson, of Ann Arbor, whose early death was a great loss to science; and Simon Newcomb, the genial savant of Washington. Chauvenet and Loomis have taught us the meaning of practical astronomy; and Olmsted, Young, Todd, and not a few others of distinction have prepared text-books that fully present the elements of the science. Nor is this fascinating study limited to the students of the 484 colleges and universities of the land. The last report of the United States Commissioner of Education shows that in the public and private high schools of the nation there are over nine thousand boys and sixteen thousand girls pursuing the study of astronomy. XIII. THE PRACTICAL USES OF ASTRONOMY AS AN AID TO NAVIGATION AND GEODESY. The practical value of this science is best appreciated by the navigator, who sees in the sun and moon his clock, and in the stars and planets the ready means of learning his latitude and longitude. It is one of the first tasks of the midshipman to become familiar with the use of the sextant, by which he works out the problem of ascertaining the exact place of the ship upon the ocean. Navigation is helpless without the assistance of astronomy. Yet it is only the A, B, C of the science that the sailor has any use for; its higher mysteries are away beyond his needs and of no practical profit to him. Nathaniel Bowditch, of Salem, Mass., in 1802, issued a book entitled “The New American Practical Navigator,” which is still a standard treatise for seamen. His rare acquirements as a mathematician were signally displayed, and in a form that has proved enduring, when, in 1814–17, he translated into English, accompanied with copious notes of his own, the profound work, “Celestial Mechanics,” penned by the gifted La Place in 1799. Although in name a translation of a foreign book with a commentary, it is in many respects an original work. Professor Elias Loomis, who left to Yale University three hundred thousand dollars as an endowment fund to aid in prosecuting astronomical research, said of him, in 1850, “Bowditch has probably done more for the improvement of physical astronomy than all other Americans combined.” Dr. Bowditch published the work in four ponderous quarto volumes wholly at his own private cost. These volumes he did not expose for sale, but generously gave them to such persons as proved to him their ability to appreciate and comprehend them. This outlay impaired the fortunes of his family, but became his own unique monument.