🔍 Key Concepts

• Magnetic equator and how the Earth’s vertical magnetic field component behaves there • Purpose of the Flinders bar, heeling magnet, and quadrantal spheres in compass correction • Which corrector(s) deal specifically with vertical components of magnetism

💭 Think About

• Ask yourself: What happens to the vertical component of the Earth’s magnetic field as you cross the magnetic equator, and why does that matter to the compass? • Which of these correctors (heeling magnet, quadrantal spheres, Flinders bar) is designed to compensate for induced vertical magnetism in the ship? • If a correcting element was set up for a vertical field pointing one way, what simple physical change would let it work correctly when that field reverses direction?

✅ Before You Answer

• Identify which device corrects heeling error due to vertical permanent magnetism and which corrects induced vertical magnetism • Confirm that quadrantal spheres relate to semicircular deviation from horizontal soft iron, not vertical components • Consider what adjustment would be needed when the direction of the vertical field component reverses at the magnetic equator