A HISTORY OF SCIENCE 



either side of this extending to the tropic; and then 

 the temperate zones extending in either direction from 

 the tropic to the arctic regions. There seems to have 

 been a good deal of dispute among the scholars of the 

 time as to the exact arrangement of these zones, but the 

 general idea that the north-temperate zone is the part 

 of the earth with which the geographer deals seemed 

 clearly established. That the south-temperate zone 

 would also present a habitable area is an idea that is 

 sometimes suggested, though seldom or never distinctly 

 expressed. It is probable that different opinions were 

 held as to this, and no direct evidence being available, 

 a cautiously scientific geographer like Strabo would 

 naturally avoid the expression of an opinion regarding 

 it. Indeed, his own words leave us somewhat in 

 doubt as to the precise character of his notion regard- 

 ing the zones. Perhaps we shall do best to quote 

 them: 



" Let the earth be supposed to consist of five zones, 

 (i) The equatorial circle described around it. (2) An- 

 other parallel to this, and defining the frigid zone of the 

 northern hemisphere. (3) A circle passing through 

 the poles and cutting the two preceding circles at right- 

 angles. The northern hemisphere contains two quar- 

 ters of the earth, which are bounded by the equator 

 and circle passing through the poles. Each of these 

 quarters should be supposed to contain a four-sided 

 district, its northern side being of one-half of the par- 

 allel next the pole, its southern by the half of the equa- 

 tor, and its remaining sides by two segments of the circle 

 drawn through the poles, opposite to each other, and 

 equal in length. In one of these (which of them is of 



262 



