OF THE COSMOS. DISTRIBUTION OF THE FIXED STARS. 117 



have been brought to Ptolemy from voyages to the southern 

 part of the Eed Sea, or between Ocelis and the commercial 

 entrepot of Muziris ( 231 ) on the Malabar coast. No doubt 

 Diego Cam in company with Martin Behaim, in 1484, on 

 the West Coast of Africa, Bartholomew Diaz in 148 1, and 

 Vasco de Gama in 1497 on the voyage to India, passed far 

 beyond the Equator, and into the Southern Ocean as far as 

 35 S. latitude ; but the first particular notice of the large 

 stars and nebulae, the description of the Magellanic clouds 

 and the ee coal sacks," and even the fame of the " wonders 

 of the heavens not seen in the Mediterranean/' belong to 

 the epoch of Vincent Yanez Pinzon, Amerigo Vespucci, and 

 Andrea Corsali, between 1500 and 1515. Star-distances 

 were measured in the southern heavens at the end of the 

 16th and the beginning of the 17th century. ( 232 ) 



Laws of relative density in the distribution of the fixed 

 stars on the celestial vault began to be recognised when 

 William Herschel, in 1785, conceived the happy thought 

 of estimating the number of stars visible in the field of view, 

 15' in diameter, of his 20 -feet reflector, at different altitudes 

 and in different directions. This laborious process of 

 " gauging the heavens" has been already repeatedly referred 

 to in the present work. The field of view embraced each 

 time only 8d ^op-p-th of the whole heavens ; and, according to 

 a remark of Struve's, 83 years would be required for the 

 completion of such gaugiugs over the entire sphere. ( 233 ) 

 In inquiries respecting the equal or unequal distribution of 

 stars, their photometric magnitudes must be particularly 

 taken into account. If we confine our attention to the 

 bright stars of the first three or four classes of magnitude, 

 we find them pretty uniformly distributed ( 234 ) on the whole ; 



