A Question for You.

In the ninetieth line of the First Book of Virgil, the first two words are Intonuere poli. The translation, as I have it, is "the poles resound," meaning that the earth echoes with the heavy thunders. Now will somebody please explain to me how the ancients knew there were poles without having some idea of the roundness of the earth? Almost the same expression is used in the 398th line, as follows, Et coetu cinxere polum, etc.

Alfred C. Baker.
Schaghticoke, New York.