ASTRONOMY OF THE NINETEENTH CENTURY. 427 



the eighth in order of discovery, was seen in America by W. Bond ; 

 and, independently, by Lassell two days afterwards in England, who 

 recognized it as a Saturnian satellite on the following day. It is one 

 of the smallest in the Saturnian system, and its place in order from the 

 planet is the seventh. 



The above-named are the principal discoveries which have added 

 new bodies to the solar system during the past portion of the nine- 

 teenth century. Many important investigations of the theories of 

 various planets and of their secondary systems have been undertaken. 

 Elaborate tables, by which the position of each planet may be found 

 for any given epoch of time, have been calculated by several astrono- 

 mers, who have introduced successively more and more corrections 

 and refinements. Examples of such tables are Lindenau's " Tables 

 of Mars," published 1811 ; his "Tables of Mercury," 1813; Delam- 

 bre's " Tables of Jupiter's Satellites," 1817; Bouvard's "Tables of 

 Jupiter, Saturn, and Uranus," 1821 ; Damoiseau's "Lunar Tables;" 

 Lubbock's "Theory of the Moon," 1834 and 1838; Damoiseau's 

 "Tables of Jupiter's Satellites," 1836; Hausen's "Lunar Tables," 



1857- 



Astronomers -have industriously laboured at forming catalogues of 

 the fixed stars, in which the position of each star shall be registered 

 with the greatest accuracy. As the value and importance of such 

 registers will hardly be understood by those who have given no special 

 attention to astronomy, the words of a late eminent astronomer may 

 be quoted : " Every well-determined star from the moment its place is 

 registered, becomes to the astronomer, the geographer, the navigator, 

 the surveyor, a point of departure which can never deceive or fail him ; 

 the same for ever and in all places ; of a delicacy so extreme as to be 

 a test for every instrument yet invented, yet adapted for the most 

 ordinary purposes ; as available for regulating a town clock as for con- 

 ducting an army." The formation of star catalogues dates from at 

 least the time of Hipparchus, and such catalogues will ultimately be 

 the means of revealing changes in the stars themselves of which we 

 have as yet scarcely any conception. Though the fixed stars serve 

 admirably for what we may metaphorically call the landmarks of the 

 heavens, their fixity is, after all, but relative ; and other purposes which 

 will be served by star catalogues, are the determination of the motions 

 which belong to each star (i.e., its proper motion) ; the change in the 

 apparent places of the stars due to the motion of the solar system 

 itself; and various physical changes in the heavens themselves, such as 

 the disappearance of stars and apparition of new ones. The amount 

 of labour devoted by the astronomers of the present century in ob- 

 servations on the fixed stars may be inferred from the following 

 tabular view of some of the star catalogues, which have been compiled 

 during the present century and published in England and elsewhere. 



