EXPLORING THE GLORIES OF THE FIRMAMENT 



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the fruits of astronomy worth all the 

 labor and thought expended on it? The 

 thoughtful man, realizing how vastly it 

 enlarges his appreciation of the great 

 First Cause, how wonderfully it teaches 

 us the stupendous smallness of our place 

 in the universe, finds it both good and 

 profitable. 



But even to the man who looks for 

 direct physical benefits and every-day 

 good, its worth will appear. Parallels 

 of latitude and meridians of longitude 

 depend upon it. time signals are born of 

 it, safe navigation at sea were impossi- 

 ble without it. State and national boun- 

 daries are often fixed by it. 



Yet the indirect benefits excel, if that 

 may be, the direct ones. When Roemer 

 discovered the velocity of light, little did 

 he suppose that the interpretation of his 

 discovery would lead to wireless com- 

 munication. 



It is interesting to have a look at our 

 own earth in its relation to the worlds 

 that people the sky. When a mighty 

 storm sweeps over the ocean, when a 

 great war devastates a continent, when 

 a Katmai blows off her head, when an 

 earthquake destroys a populous city, men 

 stand overwhelmed and awed at the spec- 

 tacle ! 



But how little and insignificant are 

 such forces, measured by the majestic 

 might of the earth as it sweeps on its 

 course around the sun ! 



An eminent physicist has estimated that 

 the power developed by a million Niag- 

 aras in a million years would not equal 

 the energy expended by the earth in a 

 single second as it circles round the sun. 



And yet so perfect is the mechanism 

 that, flying around its axis at an equa- 

 torial speed of more than a thousand 

 miles an hour, and around its orbit at 

 more than eleven hundred miles a min- 

 ute, all the mundane influences of which 

 astronomers know could not change the 

 length of its day as much as a second in 

 a hundred thousand years. 



WHERE THE EARTH BECOMES A DROP IN 

 A RESERVOIR 



But as soon as one looks out into space 

 with the eye of the astronomer, there 

 comes the discovery that in all its seem- 



ing greatness the earth is so small that 

 even a telescope ten thousand times as 

 powerful as the strongest instrument 

 now in existence would not reveal it to 

 an astronomer on any fixed star. 



Compared even with the sun, our 

 planet's insignificance becomes evident. 

 More than 1,300,000 spheres like ours 

 would be needed to make a bulk equal to 

 that of a single sun (see pages 166, 180). 



Perhaps our most graphic picture of 

 the solar system is given by Herschel. 

 Imagine a circular field two and a half 

 miles in diameter ; place a library globe 

 two feet in diameter in the very center ; 

 eighty-two feet away put a mustard 

 seed. The globe will represent the sun 

 and the mustard seed Mercury. 



At a distance of 142 feet place a pea, 

 and another at 215 feet. These will rep- 

 resent Venus and the earth, both as to 

 size and distance. A rather large pin- 

 head at a distance of 327 feet will speak 

 for Mars, and a fair-sized tangerine a 

 quarter of a mile distant will stand for 

 Jupiter. A small lemon at two-fifths of 

 a mile will play the role of Saturn, a 

 large cherry three-fourths of a mile will 

 answer for Uranus, and a fair-sized 

 plum at the very edge of the field will 

 proclaim Neptune (see pages 157. 180). 



SIGHT-SEEIXG THE SOLAR SVSTEM 



In our celestial tour there is time for 

 only a passing reference to the moon 

 and the planets. Eighty moons would be 

 required to make one earth. A player 

 there could throw a ball six times as 

 far as it can be thrown on American 

 diamonds. A man weighing 150 pounds 

 there would weigh 900 on the earth. 

 The earth receives as much light and 

 heat from the sun in thirteen seconds 

 as it gets from the moon in a whole 

 year. 



Mercury is almost the "unseen planet." 

 Being very close to the sun, it is nearly 

 always engulfed in the rays of the dawn 

 or overwhelmed in the haze of twilight, 

 and thus rarely gets a chance to shine 

 out. At some stages of its joumeyings 

 Mercury almost breaks the solar system's 

 speed limit, dashing wildly along at a 

 pace of more than two thousand miles 

 a minute. 



