A line joining places of zero declination is called

Lines joining the places of zero declination is called

A line joining places of equal declinaiton is called

In a magnetic map, the line joining the places of zero dip is called an aclinic line. This line can also be called

Lines joining the places of zero Dip' is called

Lines joining the places of equal 'declination' are called

Lines joining places of equal angle of declination are called