POLES AND EQUATOR. 



the equator is expressed by stating the number of degrees of a 

 terrestrial meridian included between the place and the equator. 

 This is called the LATITUDE of the place ; which is the distance 

 of the place from the equator expressed in degrees of the meri- 

 dian. Thus, if a place be midway between the pole and the 

 equator, its latitude is 45. If it be distant from the equator by 

 two-thirds of the entire distance from the equator to the pole, its 

 latitude will be 60, and so on. 



3. The latitude is said to be northern and southern/according 

 as the place is in the northern or southern hemisphere. 



But it is evident that the latitude alone will be insufficient for 

 the determination of the position of a place. If we state that a 

 certain place is 45 north of the equator, it will be impossible to 

 ascertain certainly the place in question, inasmuch as there is a 

 circle of points on the earth, all of which are 45 north of the 

 equator. If we suppose a circle drawn round the surface of the 

 northern hemisphere parallel to the equator, at the distance from 

 the equator of 45 3 , every point of such circle will be equally 

 characterised by the latitude of 45 north. 



Such a circle is called a PARALLEL OF LATITUDE, and it is 

 therefore apparent that wherever such a parallel may be drawn 

 upon the earth, all the places upon it will have the same latitude. 



In the figure E N Q is the northern and E s Q the southern 

 H 2 9 



