140 COSMOS. 



the Cosmos, man would have been left without all those in- 

 citements which, for thousands of years, have incessantly im- 

 pelled him to the soluticfn of important problems, and have 

 exercised so beneficial an influence on the most brilliant 

 progress made in the higher spheres of mathematical develop- 

 ment of thought. Before we enter upon an enumeration of 

 what has already been achieved, let us dwell for a moment on 

 the danger from which the spiritual development of our race 

 has escaped, and the physical impediments which would have 

 formed an impassable barrier to our progress. 



In considering the number of cosmical bodies which fill 

 the celestial regions, three questions present themselves to 

 our notice. How many fixed stars are visible to the naked 

 eye ? How many of these have been gradually catalogued, 

 and their places determined according to longitude and lati- 

 tude, or according to their right ascension and decimation ? 

 What is the number of stars from the 1st to the 9th and 10th 

 magnitudes, which have been seen in the heavens by means 

 of the telescope ? These three questions may, from the ma- 

 terials of observation at present in our possession, be deter- 

 mined at least approximatively. Mere conjectures based on 

 the gauging of the stars in certain portions of the Milky Way, 

 differ from the precediog questions, and refer to the theo- 

 retical solution of the question: How many stars might be 

 distinguished throughout the whole heavens with HerscheFs 

 twenty-feet telescope, including the stellar light " which is 

 supposed to require 2000 years to reach our earth ?" 8 



The numerical data which I here publish in reference to 

 this subject, are chiefly obtained from the final results of my 

 esteemed friend Argelander, director of the Observatory at 

 Bonn. I have requested the author of the Durchmusterung 



On the space-penetrating power of telescopes, see Sir 

 John Herschel, Outlines of Astr., 803. 



