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752 of the Royal Observatory at Greenwich. Since that time he has regularly presented to the Board of Visitors of the Royal Observatory an annual report, and of these the fortieth lies before us. In many respects it is like its predecessors; it gives, as they have done, full, even minute accounts of the present condition of the "Buildings and Grounds," of the "Movable Property," of the "Manuscripts," of the "Library," of the "Astronomical Instruments" (in detail), of the "Astronomical Observations" (also in great but necessary detail), of "Spectroscopic and Photographic Observations," of the state of the "Reduction of Astronomical Observations," and of the "Reduction of Photographic and Spectroscopic Observations," of the "Printing" of all the results, of "Magnetic and Meteorological Observations," of the "Chronometers, Time Signals, and Regulation of External Clocks," of the "Personal Establishment," of "Extraneous Work;" and it closes, as its predecessors have done, with a few concise "Remarks" which this year are more interesting and important even than in preceding years.

In other Reports it has been the custom of the Astronomer Royal to draw whatever lessons seemed proper from the work of the past years for the guidance of the observatory in the future, and this has been done in the most concise manner. In this Report the doings of the Observatory in the past and its work for the years to come are spoken of with more freedom and fullness; with so much freedom as to lead some of Mr. Airy's critics in England to speak of it with a kind of fierce joy as his "Valedictory," although nothing is said in it of his retirement. It is impossible to read it without intense interest and without exclaiming, "What a memorable valedictory it would make!"

For forty years the present Astronomer Royal has been the active head of the Greenwich Observatory, and he has been in the most active way concerned in many scientific councils; as he says, "there is not a single assistant of a single instrument in use of those which formed the establishment in 1835," and yet in all these years he has kept steadily one main object in view, and as far as one man can attain it he has attained it. He has gained, with the success of his astronomical plans, the entire and thorough respect and esteem of the scientific world in general, and he may now lay down, if he will, the duties which he has borne so long, sure of the honor and admiration of two generations of his contemporaries.

He points out in this Report, as he has insisted in other Reports, that the Greenwich Observatory was expressly built for promoting methods for determining the longitude at sea, and he shows how the work of Flamsteed, Halley, Bradley, Maskelyne, and Pond (his illustrious predecessors) has been more or less steadily devoted to this object. By none of these, however, has this end been so unremittingly followed as by Airy himself. All the main instruments which the observatory at present possesses, with the exception of the equatorial, may be truly said to have been designed by him with principal reference to the determination of the elements upon which a knowledge of the motion of the moon depends. "Elaborate Star Catalogues" have been formed and immediately published, which are deduced in a uniform manner from the observations, which were made in a uniform way. One steady plan has been followed from 1835 until now, by which results of the very highest value have been attained. The whole astronomical work has been done in one way, and that a wise one; it has been all reduced in one way, probably the best one, and it has been promptly published. This alone would lead to great success. But this is not all: the masses of observations of the moon and major planets which had accumulated from 1750 to 1835 have been carefully taken up, separated, sifted, and discussed upon a predetermined and elaborate plan, and immediately made available to theoretical astronomers. "The lunar reductions are probably the greatest single work ever undertaken in astronomy," so Airy himself says, and he is right beyond a doubt. The needs of astronomy and navigation have been constantly kept in view; the subject of the laws of magnetism in iron ships has been carefully studied, and methods for the correction of ships' compasses have been devised, which are used throughout the world;