20 FIRST YEAR COURSE IN GENERAL SCIENCE 



realize what these words mean. Supposing that an express 

 train were traveling every day a thousand miles (about 

 the distance from Chicago to Boston), it would take two 

 years and nine months to travel one million miles. 



Light passes from one place to another so rapidly that 

 we think of its passage as instantaneous, that is, as taking 

 no time at all. It has been proved, however, that light 

 takes eight minutes to come from the sun to the earth, 

 nearly ninety-three millions of miles. The nearest star is 

 so far away that its light takes more than four years to 

 come from the star to the earth. The light that we re- 

 ceive from the North Star to-night started nearly seventy 

 years ago. Many stars are much more distant. 



9. Why we should Know the North Star. For de- 

 termining direction, especially in navigation, the North Star 

 is of very great importance. It is so situated that at most 

 places north of the equator it can be seen in the northern 

 part of the sky throughout any clear night in the year. It 

 does not seem to change its position from hour to hour, as 

 other stars do. The North Star is also called Polaris, or the 

 Pole Star, because the imaginary axis of the earth, if 

 extended from the north pole, would pierce the sky very 

 near to this star. The stars in the northern sky seem to 

 revolve about the Pole Star, just as all the lands near the 

 north pole of a terrestrial globe seem to revolve around that 

 point as the globe is rotated. 



When we are looking directly at the North Star, we are 

 facing north, and the point on the horizon in a vertical line 

 below the star is the north point. As one travels northward, 

 the North Star seems to rise higher and higher above the 

 horizon. Commodore Peary must have seen it at the zenith, 

 that is, directly overhead when he reached the north 

 pole in 1909. He was then ninety degrees from the equator, 

 and the distance from the horizon to the zenith, where he saw 

 the North Star, is ninety degrees. The number of degrees of 



