Homemade Compass

Homemade Compass

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One of the things that originally drew European explorers and settlers to what is now Des Plaines is the river: like many other rivers and waterways, the Des Plaines River was a kind of highway that boats and canoes could use to quickly get from one place to the next. Some of these travelers were traders looking for furs and other goods that could be traded at settlements and with Native Americans in the area. Other people were explorers, trying to map out what was then unknown territory to European empires. But wait, how can you find your way in an unfamiliar place with no map?

One important tool would be the magnetic compass, a device that indicates direction. That way, explorers could better understand where they’ve been, and help create maps. Magnetic compasses consist of a magnetized needle that is allowed to rotate so it lines up with the Earth's magnetic field. The ends point to what are known as magnetic north and magnetic south. Compasses have taken on many different designs since they first appeared in ancient China as early as 2000 years ago, but here’s a very simple compass that you can make at home!

You’ll need:

- A steel sewing needle

- A magnet - the stronger the better!

- A cork or small circle of wax paper

- A medium or large bowl

- Water

Step 1: Magnetize the needle. With your adult’s help, hold the needle by the eye end, and take your magnet and stroke it down the length of your needle 50 times. If you are using a weaker magnet you may need to do this more than 50 times. But for most good quality magnets 50 should be about right.

Step 2: Magnetize the other end with the reverse. Carefully flip the needle around so you are holding the pointy end, and flip over the magnet so you are using the other side of the magnet. Now repeat on the non-magnetized end of the needle.

Step 3: Preparing the float. Cut either a small circle from your cork (about 1-2cm thick), or a small circle of wax paper that fits in the center of your bowl.

Step 4: Insert the needle. Have your adult help you push the needle through the sides of your cork, using a thumbtack to make a starting hole. If you’re using wax paper, have your adult carefully thread the needle through the paper so that the needle lies flat on top of the paper. In either case, your needle should be at the center of the cork or paper.

Step 5: Fill a bowl with water. Set out your bowl and fill it with a few inches of water.

Step 6: Test the compass! Place your cork and needle in the water and see how it moves. It should align itself so it points North. If you have a smartphone handy, you can check your work with a digital compass.

What we did here was turn the needle into a weak, temporary magnet by rubbing it with the larger magnet - you can test this by using your needle to attract other small metal objects! Because magnets interact with one another, either attracting or repelling, the magnetized needle can interact with the Earth’s magnetic field. Allowing it to float freely on the water, allows the magnetized needle to freely react to Earth’s magnetic field, causing it to align North to South. Be sure to place your compass away from items and material that have iron in them—many kitchen appliances are steel and some granite counters have a lot of iron in them!

Once you’re satisfied with your compass, try using it around your yard or house to make your own map! You can also create a second compass and add it to the same bowl of water. What happens? What happens if you bring your magnet near the water? What happens if you spin the compass?