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THE POPULAR SCIENCE MONTHLY. 



ship of the Royal Observatory at Green- 

 wich. Since that time he has regularly 

 presented to the Board of Visitors of the 

 Koyal 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 de- 

 tail), of the " Astronomical Observations " 

 (also in great but necessary detail), of 

 " Spectroscopic and Photographic Observa- 

 tions," of the state of the " Reduction of 

 Astronomical Observations,"" and of the 

 " Reduction of Photographic and Spectro- 

 scopic Observations," of the " Printing " 

 of all the results, of " Magnetic and Mete- 

 orological Observations," of the " Chronom- 

 eters, Time Signals, and Regulation of Ex- 

 ternal Clocks," of the "Personal Estab- 

 lishment," 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 ob- 

 servatory in the future, and this has been 

 done in the most concise manner. In this 

 Report the doings of the Observatory in 

 tlie past and its work for the years to come 

 are spoken of with more freedom and full- 

 ness ; 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 " Vale- 

 dictory," although nothing is said in it of 

 his retirement. It is impossible to read it 

 without intense interest and without ex- 

 claiming, " What a memorable valedictory 

 it would make !" 



For forty years the present Astronomer 

 Royal has been the active head of the Green- 

 wich Observatory, and he has been in the 

 most active way concerned in many scien- 

 tific councils; as he says, "there is not a 

 single assistant oi a single instrument in 

 use of those which formed the establish- 

 ment 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 scien- 

 tific 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 admi- 

 ration of two generations of his contempo- 

 raries. 



He points out in this Report, as he has 

 insisted in other Reports, that the Green- 

 wich Observatory was expressly built for 

 promoting methods for determining the lon- 

 gitude at sea, and he shows how the work 

 of Flamsteed, Halley, Bradley, Maskelyne, 

 iind 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 pos- 

 sesses, with the exception of the equatori- 

 al, may be truly said to have been designed 

 by him with principal reference to the de- 

 termination of the elements upon which a 

 knowledge of the motion of the moon de- 

 pends. "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 re- 

 sults 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, prob- 

 ably 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, sep- 

 arated, sifted, and discussed upon a prede- 

 termined and elaborate plan, and immedi- 

 ately made available to theoretical astrono- 

 mers. " 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 con- 

 stantly kept in view ; the subject of the 

 laws of magnetism in iron ships has been 

 carefully studied, and methods for the cor- 

 rection of ships' compasses have been de- 

 vised, which are used throughout the world ; 



