78 SPECIAL RESULTS IN THE URANOLOGICAL 



form : ( 149 ) I only allude to them here, because T shall sub- 

 sequently have to notice certain peculiarities of motion 

 ascribed to the star Procyon, which appear to point to a 

 perturbation by dark bodies. It is the object of this part of 

 my work to touch on matters which, during the time in 

 which it has been in progress, have influenced the direction 

 which science has pursued, and thus to mark the individual 

 character of the epoch in regard to the study of Nature, 

 whether in the sidereal or the telluric sphere. 



The photometrical relations, or relative brightness, of the 

 self-luminous bodies which fill space, have formed a subject 

 of scientific observation and estimation for more than two 

 thousand years. The description of the starry heavens in- 

 cluded not only the determinations of place, the measure- 

 ment of the angular distances of the heavenly bodies, and of 

 their paths relatively to the apparent course of the sun and 

 the diurnal movement of the celestial vault, but also the 

 relative intensity of light in different stars. It was no 

 doubt the subject which earliest drew the attention of men ; 

 single stars received names before they were combined 

 with others into imaginary groups or constellations. Among 

 the small savage tribes inhabiting the densely wooded 

 districts of the Upper Orinoco and Atabapo, in places where 

 the impenetrable thickness of the forest usually obliged me 

 to observe only high culminating stars for determinations of 

 latitude, I often found single individuals, especially old men, 

 who gave particular names to Canopus, Achernar, the feet 

 of the Centaur, and the principal star in the Southern Cross. 

 Supposing the list of constellations which we have under the 

 name of the Catasterisms of Eratosthenes really to possess the 



