“Men,” said he, steadily turning upon the crew, as the mate handed him the things he had demanded, “my men, the thunder turned old Ahab’s needles; but out of this bit of steel Ahab can make one of his own, that will point as true as any.”
Abashed glances of servile wonder were exchanged by the sailors, as this was said; and with fascinated eyes they awaited whatever magic might follow…”
-Melville, Moby Dick, 1851
Sewing needle about 1-2 inches long
Small bar magnet or refrigerator magnet
A small piece of cork (a flat piece from a wine bottle works but make sure it is cork and not plastic)
A shallow bowl
WARNING: Needles are sharp! Use caution.
Let's Make a Compass
To magnetize the needle: Rub a magnet along the needle a few times in one direction only
Cut off a small circle at one end of the cork (about ¼’ thick)
- Securely grip the needle with the pliers and with the circle of cork on a flat surface, push the needle through one end of the cork and out the other so that the needle is sticking out of both ends of the cork evenly. (Be careful)
Fill the bowl half-way with water and float the “compass” on the surface of the water
Place the whole “compass” on a flat surface and watch the needle as it tries to align itself with the magnetic fields. The needle should point towards the nearest magnetic pole (north or south) depending on where you live.
- Now go test out your new compass and see if you can orient yourself on a map!
What happens if you put a magnet near your compass? Does anything happen to your compass if you put other metal objects near your compass? If you were using a compass on a ship, would you want metal objects near your compass?
Why Your Compass Works:
Magnetic fields are created by rotating electrical charges. Our planet Earth produces a magnetic field and has a north and south magnetic pole.
- Your compass can point towards these poles because the magnetized needle in the cork is floating and allowed to freely rotate in the water in order to align itself with Earth’s magnetic fields.
Last updated: May 16, 2016