312 DISCOVERY OH. 



If these devout thoughts inspired the Psalmist when 

 he considered the heavens, what words are now adequate 

 to express the feelings to which increased knowledge of 

 the universe should give rise ? Less than three thousand 

 stars can be seen when a watcher, unaided by optical 

 power, looks upward on the finest night ; but even a 

 small telescope or field-glass will show many times this 

 number. With the great lenses which are directed 

 heavenward in these days, it is possible to see one hundred 

 million stars in the whole celestial sphere, instead of the 

 few thousand visible to the naked eye. 



Carry your mind back to pre-telescopic times, and 

 consider what was then conceived to be the content and 

 extent of the universe visible to man. Nothing could 

 be known of the stars and other celestial objects beyond 

 the range of unaided vision, and not the boldest of the 

 speculative philosophers imagined that there were 

 millions of celestial bodies in addition to those which 

 were within their bounds of knowledge. What they saw 

 seemed to be the beginning and end of things celestial, 

 and there was no thought of anything beyond it. 



Astronomy, more perhaps than any other science, 

 teaches the imperfection of human understanding, and 

 hesitates to set limits to the planes which may be attained 

 in the future. Celestial things are rarely what they seem. 

 A brilliant sky at night gives the impression of infinite 

 calm and peace, and we speak of the " fixed " stars, 

 whereas not a single one is at rest, and many are moving 

 through space with velocities greatly in excess of any 

 express train on the Earth. It is difficult also for anyone 

 unacquainted with astronomy to believe that the Earth, 

 and other members of the Solar system, in addition to 

 their movement of revolution around the Sun, are being 

 carried by the Sun into unknown regions of space at 



