IN DESCRIPTIVE ASTRONOMY. 121 



twenty-five trillions of miles in width, separates Neptune from 

 the nearest fixed star. It has been estimated that the average 

 distance between two of the sixty millions of fixed stars visible 

 to our largest telescopes, is about nine millions of millions of 

 miles. With this amount of "elbow-room," a collision between 

 any two such remote neighbors would be almost impossible. 

 Yet, Sir Wm. Thomson remarks: "It is as sure that collisions 

 must occur between great masses moving through space, unless 

 guided in their paths, as it is that ships, steered without intelli- 

 gence, could not cross and recross the Atlantic for thousands of 

 years with immunity from collisions." 



t>. Is the real day longer or shorter than the apparent 

 one? 



(See Astronomy, p. 264.) 



6. Do we ever see the stars ? . 



(See Astronomy, p. 203.) 



7. What fined star is nearest the earth ? 



(See Astronomy, pp. 204, 241.) 



8. Hoiv often is Polaris on the meridian of a place? 



As Polaris revolves about the true pole in a circle, the 

 radius of which is nearly l|-, it follows that in every twenty- 

 four hours it is once on the meridian below the pole, and, also, 

 once above it. The diameter of this circle is the length of 

 Orion's Belt, the stars at the right and the left of the central 

 one representing the distance the polar star goes to the right 

 and left of the pole. 



9. How do we Jcnow that the stars are suns ? 



(See Astronomy, pp. 205, 261.) 

 Spectrum analysis proves this to be the fact. 



10. Can a watch keep apparent time? 



(See Astronomy, p. 265.) 



11. How could a child be eight years old before a re- 

 turn of its birthday ? 



An infant born on Feb. 29, 1796, did not have a birthday 

 proper until Feb. 29, 1804, since the year 1800, not being 



