SIDEREAL ASTRONOMY. 333 



The labours of astronomers have of late been sedulously 

 and worthily directed to the formation of catalogues and 

 maps of stars ; in which their places are fixed with accuracy 

 enough to permit the recognition of any changes occurring 

 amidst them. The phenomena of proper motion, and of the 

 appearance of new stars or the disappearance of old ones 

 all objects of great interest to the science have derived 

 much illustration from the labours thus directed. These 

 Star-Maps have fulfilled another important purpose in aiding 

 the discovery of planetary bodies belonging to our own 

 system. Of the numerous planetoids now discovered between 

 Mars and Jupiter, the greater number may be considered as 

 due to this method of assisting and correcting observation. 

 We have a more illustrious example to the same effect in the 

 circumstances of the discovery of Neptune ; which we believe 

 to have been aided by a particular sheet of the Star-Maps of 

 the Berlin Academy, published only a few days before Galle 

 directed his telescope in search for the predicted planet. 

 This great Prussian work, representing the stars to the 9th 

 magnitude inclusive and many of the 10th, in a cycle of 15 

 on each side of the equator, is now approaching its com- 

 pletion. The number of stars included in it will fall little 

 short of 200,000. Bessel, Harding, Argelander, and others 

 have laboured in the same vast field ; and the zone to which 

 Argelander has extended his observations has afforded him 

 already a list of more than 100,000 stars. Our own 

 countryman, Mr. F. Baily, devoted the latter years of his 

 valuable life to the British Association Catalogue, founded on 

 those of Lalande and Lacaille ; and the Koyal Observatory 

 at Greenwich has largely contributed to the same department 

 of astronomy. It is impossible to appreciate too highly 

 the scientific value of these labours. Had we possessed 

 catalogues equally complete of the time of Hipparchus, 

 numerous facts in sidereal astronomy would probably have 



