SOME ASPECTS OF AMERICAN ASTRONOMY 69 



which we can never make an experiment? On certain oc- 

 casions we see the moon pass in front of the sun and hide it 

 from our eyes. To an observer a few miles away the sun 

 was not entirely hidden, for the shadow of the moon in a total 

 eclipse is rarely 100 miles wide. On another continent no 

 eclipse at all may have been visible. Who shall take a map 

 of the world and mark upon it the Hne on which the moon's 

 shadow will travel during some eclipse a hundred years hence? 

 Who shall map out the orbits of the heavenly bodies as they 

 are going to appear in a hundred thousand years? How shall 

 we ever know of what chemical elements the sun and the stars 

 are made? All this has been done, but not by the intellect 

 of any one man. The road to the stars has been opened only 

 by the efforts of many generations of mathematicians and 

 observers, each of whom began where his predecessor had 



left off. 



We have reached a stage where we know much of the 

 heavenly bodies. We have mapped out our solar system 

 with great precision. But how with that great universe of 

 millions of stars in which our solar system is only a speck of 

 star dust, a speck which a traveler through the wilds of space 

 might pass a hundred times without notice? We have learned 

 much about this universe, though our knowledge of it is still 

 dim. We see it as a traveler on a mountain top sees a distant 

 city in a cloud of mist, by a few specks of glimmering Ught 

 from steeples or roofs. We want to know more about it, its 

 origin and its destiny; its limits in time and space, if it has 

 any; what function it serves in the universal economy. The 

 journey is long, yet we want, in knowledge at least, to reach 

 the stars. Hence we build observatories and train observers 

 and investigators. Slow indeed is progress in the solution 

 of the greatest of problems, when measured by what we want 

 to know. Some questions may require centuries, others 

 thousands of years for their answer. And yet never was 

 progress more rapid than during our time. In some direc- 

 tions our astronomers of to-day are out of sight of those of 

 fifty years ago; we are even gaining heights which twenty 

 years ago looked hopeless. Never before had the astrononier 

 so much work— good, hard, yet hopeful work— before him 



