STELLAR LIGHT. 119 



|>eculitirities of motion ascribed to Procyon, which appeared 

 to indicate a disturbance from dark cosmical bodies. It is the 

 object of the present portion of this work to notice the. 

 different directions to which scientific inquiry had inclined, 

 at the period of its composition and publication, and thus to 

 indicate the individual character of an epoch in the sidereal 

 as well as the telluric sphere. 



The photometric relations (relations of brightness) of the 

 self-luminous bodies with which the regions of space are filled, 

 have for more than two thousand years been an object of 

 scientific observation and inquiry. The description of the 

 starry firmanent did not only embrace determinations of places, 

 the relative distances of luminous cosmical bodies from one 

 another and from the circles depending on the apparent course 

 of the sun and on the diurnal movement of the vault of heaven ; 

 but it also considered the relative intensity of the light of the 

 stars. The earliest attention of mankind was undoubtedly 

 directed to this latter point ; individual stars having received 

 names before they were arranged with others into groups and 

 constellations. Among the wild tribes inhabiting the densely 

 wooded regions of the Upper Orinoco and the Atabapo, where 

 from, the impenetrable nature of the vegetation I could only 

 observe high culminating stars for determinations of latitude, 

 I frequently found that certain individuals, more especially 

 old men, had designations for Canopus, Achernar, the feet of 

 the Centaur and a in the Southern Cross. If the catalogue of 

 the constellations known as the Catasterisms of Eratosthenes, 

 can lay claim to the great antiquity so long ascribed to it, 

 (between Autolycus of Pitane and Timocharis, and therefore 

 nearly a century and a half before the time of Hipparchus,) 

 we possess in the astronomy of the Greeks a limit for the period 

 when the fixed stars had not yet been arranged according to 

 their relative magnitudes. In the emuneration of the stars 

 belonging to each constellation, as given in the Catasterisnis % 



