LOCATION 



455 



east and west of a prime meridian according to the difference between 

 Greenwich and the place. The units of measure are degrees, minutes, 



FIG. 344. A pocket compass. 



FIG. 345. A hunter's compass, 



and seconds. The distance around 

 the earth is divided into 360 degrees. 



The sign for degrees is " "; for 

 example, 85. 



The sign for minutes is "'"; for 

 example, 15'. 



The sign for seconds is """; for 

 example, 25". 



The illustration 88-20'-10" means 

 88 degrees, 20 minutes, 10 seconds. 



The Greenwich Royal Observatory 

 is located in the eastern part of London 

 on the Thames. From the meridian 

 on which this observatory is located 

 longitude is usually reckoned. For 

 example, if it is 6 o'clock in the morn- 

 ing at a certain point on the earth 

 when it is 12 o'clock at Greenwich 

 there is a difference of 6 hours in time. 





FIG. 346. A ship's compass. 



