agonic line

noun

1. an imaginary line on the surface of the earth connecting all points at which the declination of the magnetic field of the earth is zero.

agonic line

noun

1. an imaginary line on the surface of the earth connecting points of zero magnetic declination

agonic line

/ ā-gŏn′ĭk /

1. An imaginary line on the Earth's surface connecting points where the magnetic declination is zero. The agonic line is a line of longitude on which a compass will show true north, since where magnetic declination is zero, magnetic north coincides with geographic north.

Word History and Origins

Origin of agonic line¹

First recorded in 1860–65

Example Sentences

These two observations, one by Columbus and the other by Cabot, sufficed to determine the position of the agonic line, or line of no variation, for that locality and epoch.

From Project Gutenberg