568 



EVERYDAY SCIENCE 



(KL, Figure 1) is "straight down." Now if a line should be drawn at 

 the earth's surface (TD, Figure 2) at right angles to the first line, it 



would indicate* our horizon, or line of 

 vision along the earth's surface. The 

 line TD on the board (Figure 1) is drawn 

 at right angles to the plumb line and 

 may, therefore, be regarded as our horizon 

 line. 



Now suppose we were standing at the 

 north pole (K, Figure 2). The North 

 Star would be directly overhead, and the 

 line of light from the star to the eye 

 (K N-S, Figure 2) would be at right 

 angles, 90, to our horizon line (TD, Fig- 

 ure 2). Thus the angle of the North Star 

 above the horizon line at the north pole, 90, 

 equals the latitude of the north pole, 90. 

 Suppose we should travel along a meridian line to a point midway 



between the north pole and the equator, 45 latitude (K, Figure 3). 



The North Star would no longer be overhead, but would be about half- 



FlGURE 2 



D 



I) 



FIGURE 3 



FIGURE 4 



way between the zenith and the horizon. The line of light from Polaris 

 to the eye (K N-S, Figure 3) would, therefore, form about half a right 

 angle, 45, with our horizon line (TD). 



Suppose we should travel on to the equator, latitude (K, Figure 

 4). The North Star would then be on the horizon. The line of light 



