4 BROWN : 



of the sun, though with irregular month!}', instead of yearly, 

 periods. As to her being seen, that is another matter. During 

 the long polar da}^ her light, when she is " up," is wholly lost 

 in the beams of the sun ; and during the polar night she will 

 revolve within view in a path generally horizontal for about 

 half the time of her circuit ; sometimes more than half, some- 

 times less ; the reason of the difference being that she is not 

 on the ecliptic, Init only near it, above or below, as already 

 stated. A little pondering may be necessaiy in order to see 

 this clearly, since the fact is only darkly set forth by the 

 astronomers' statement that the nodes of the moon's orbit are 

 in a constant state of retreat upon the ecliptic. 



The movements of the planets are not so simple. The 

 paths they trace upon the heavens are the combined result of 

 their own motions and those of the earth. 



Such planets as need concern us remain much nearer the 

 ecliptic than the moon does. \"enus, the most extravagant in 

 the correct sense of the word, moves within a zone 3° 23' 

 above, 3° 23' below the ecliptic. Mercury pervades a belt in 

 .all fourteen degrees and a quarter wide, but he is rarely seen. 

 (I saw him the other evening, February 9th, 1S95, by the 

 way, after my attention had been called to him by our lecturer 

 on astronomy.) As for the Asteroids, as they are invisible 

 without the aid of a telescope, and not at all impressive when 

 so seen, it will interest us but little to remember that the most 

 extravagant of them, Pallas, has an orbit whose plane is 

 inclined to that of the ecliptic at an angle of more than 34^-2 

 degrees . 



Let the time be summer solstice at the North Pole. The 

 sun is 23 V2 degrees above the horizon. L,et the observer now 

 be transported, instantly, down the meridian on which the sun 

 is, and towards the sun. When he has been moved 23° 30' it 

 is clear that he will be on the Arctic Circle ; the time of day 

 noon ; and the sun at its greatest possible altitude for that 

 parallel. Ikit if the same movement from the pole had taken 

 place away from the sun the observer would have found him- 



