magnetic needle

Seeing how the master-mariner honours the magnetic needle, every thoughtful passenger will probably consult it in like manner.

Under these conditions it is obvious that the magnetic needle is quite useless for steering purposes.

The former is called the variation, and the latter the dipping of the magnetic needle.

In the present instance the line of force appears to coincide with the direction of the magnetic needle.

This deflection of the magnetic needle is due to the fact that surrounding every electric current are magnetic lines of force.