LOCAL MAGNETIC MERIDIAN. 



43 



The general direction of the Local Magnetic Meri- 

 dian may be obtained by merely observing the direc- 

 tion of the needle : but the Astronomical Meridian is 

 not so obviously visible : and therefore the Declination 

 cannot be easily found. Navigators however require 

 the Declination in order to enable them to adapt their 

 compass-steering to ordinary maps and charts. The 



Fig. 17. 



Fig. 17*. 



element required was obtained by the use of an 

 ' azimuth compass' represented in Figures 17 and 17*. 



