792 Home Nature-Study Course. 



o'clock in the evening in the middle of December the Big Dipper is below the Pole 

 Star and at the right ; the middle of January it is as high as the Pole Star and 

 at the right, while in the middle of May it is directly over the Pole Star. 



The Pole Star is so called because the north end of the first axis is directed 

 toward it. The children should be made to understand that this is merely a co- 

 incidence. The North Star has nothing to do with the axis of our earth, but 

 simply happens to be nearly in a line toward which the axis points. It is also a 

 coincidence that the needle of the mariner's compass points toward the North Star. 

 The earth itself is a large magnet and exerts an influence on all magnetizable sub- 

 stances. The poles of this great earth magnet are situated near the axis of its 

 revolution; therefore, the needle of the compass naturally points north and south, 

 and has nothing whatever to do with the North Star except that it points in its 

 direction. The Pole Star when it is visible enables the sailors on the waters of the 

 Northern Hemisphere to find their position. The Pole Star is not visible in the 

 Southern Hemisphere, and there is no star which happens to lie directly above 

 the South Pole. The reason why the Pole Star and the constellations about it do 

 not rise and set in the Northern Hemisphere is that the Pole Star being directly 

 above our North Pole is always in sight above the horizon. The nearer we ap- 

 proach the Pole the higher the North Star is in the heavens and if an observer 

 were stationed at the North Pole he would see the Pole Star directly above his 

 head, and he would see only half of the stars of the heavens and these would never 

 rise or set, but appear to move around in circles parallel to the horizon. If the 

 pupils have studied geography you will be able to explain to them that the Big 

 Dipper and the other constellations do not revolve about the North Star, but only 

 seem to do so, because the earth from which we make our observations is revolving. 



The Big Dipper was known to the ancients and is called by astronomers to-day 

 the Great Bear. The stars which form the legs and head of the bear may be seen 

 in Stories of Starland, p. Ii6. As a nature-study teacher, it would be well to ask 

 the pupils about the difference in the length of tail between these bears set in the 

 sky and the bears which they see in the menageries. 



Lesson XXX. 



THE LITTLE DIPPER. 



Purpose. — To learn to see this constellation and note its relation to the 

 North Star and the Big Dipper. 



Method of teaching. — Make on the blackboard a picture like the ac- 

 companying one and tell the pupils how to find the Little Dipper by its 

 curved handle, the tip end of it being the Pole Star itself. Show how it 

 opens toward the Big Dipper, as if the two dippers pour toward each 

 other, and that its bowl does not flare like the bowl of the Big Dipper. 

 Let the pupils make their observations by themselves and ask these 

 questions. 



