A compass is a small bar magnet (with a north pole and a south pole) suspended such that it is free to rotate in a horizontal plane.
(A compass; is; a small bar magnet (with a north pole and a south pole) suspended such that it is free to rotate in a horizontal plane) (it; is; free to rotate in a horizontal plane) (it; to rotate; L:in a horizontal plane)
A compass it it
is is to rotate
a small bar magnet (with a north pole and a south pole) suspended such that it is free to rotate in a horizontal plane
free to rotate in a horizontal plane
L:in a horizontal plane