THE ENGLISH OBSERVATORIES. 531 



of vessels, so that his astronomers would be able, by the study of the 

 movements of the heavens, to direct the distant courses of ships over 

 the surface of the sea. The interest of the marine was in reality the 

 controlling motive that determined the foundation of this establish- 

 ment. The ordinance of 1673 decrees that "the astronomer royal 

 shall devote his time to rectifying the tables of celestial bodies and 

 the positions of the fixed stars in order to obtain the means of finding 

 the longitude at sea." To indicate in a precise manner the position 

 of the stars, to predict with certainty the course of the moon in rela- 

 tion to these fixed data, is the great work reserved lor sedentary as- 

 tronomy in the progressive improvement of the art of navigation. 

 The heavens constitute, as it were, a revolving dial-plate, on which the 

 moon, making her way from star to star, marks for the navigator the 

 absolute time, the time at Greenwich, while the height of the sun 

 above the horizon furnishes the time of the place where he chances to 

 be, and it is by comparison that he finds out his longitude, that is, the 

 meridian under which he is passing. The regular and long-continued 

 observation of the fixed stars, sun and moon, was then traditional in 

 this illustrious establishment of Greenwich, which has had for directors 

 such astronomers as Flamsteed, Halley, Bradley, Maskelyne, Pond, 

 and George-Biddell Airy, who has been director since 1835. It is 

 there that the first foundation of modern astronomy has been laid, 

 that is to say, the astronomy of precision. Far from seeking an easily- 

 obtained glory in the discoveries, more brilliant than really important, 

 that strike the mind of the crowd, the Greenwich astronomers have in- 

 variably applied themselves to the laborious investigation of those 

 minutiee upon which the edifice of science reposes, and where often the 

 trace of great unknown laws is revealed. 



Flamsteed, the first director, made all his observations by the aid 

 of a sextant and a mural arc, which were his own private property ; the 

 first reports were printed without his consent, and were so imperfect 

 that he burned all of the first edition that had not been distributed, in 

 order to have a new one made under his own inspection, and at his 

 own expense. His successor, Halley, found the building stripped of 

 all the apparatus ; the heirs of Flamsteed had carried away every 

 thing. This was perhaps a piece of good fortune for science, as Hal- 

 ley was obliged to procure new instruments, and in 1721 he caused a 

 transit instrument to be constructed. This became the prime mover 

 in astronomical researches, and the observations that Bradley made 

 with its aid are the points of departure for our catalogues of the stars, 

 for they permit us to appreciate with certainty the changes that have 

 been brought about by time in the relative situation of the fixed stars, 

 and consequently to reduce the observations of each day to a given 

 epoch. 



When Bradley was called, in 1742, to the direction of the Greenwich 

 Observatory, he was already celebrated by discoveries of the first order, 



