Compasses have guided explorers and Earth scientists for thousands of years. The origin of the compass is hard to pin down - scientists in China understood that the Earth had a magnetic field as far back as 2637 BC. However, it wasn't until 1190 AD when the first written description of a compass and its uses in navigation appeared in Europe. Explorers used the compass to aid in oceanic voyages, where sailors could get disoriented from the lack of shorelines used as points of reference.
Modern Compasses
Today, compasses are more elaborate and technologically advanced. The most common type of compass currently used by geologists is the Brunton compass. This compass not only gives accurate geographic directions down to the degree (between 0 and 360), but it is also designed to allow geologists to measure the inclination of a slanted bed of rocks - also known as the "dip" of a rock formation. Many scientists now use an even more high-tech compass called a Global Positioning System (GPS) to orient themselves and navigate around the world. A GPS uses information from satellites to get the exact geographic location of an individual anywhere in the world.
Make A Compass
It's very easy to make a simple compass that can give the general direction of true North or South, which can then be used to navigate in the directions of North, South, East and West. The general idea behind the technology of compasses is that there are magnetic fields in the North and South poles of the Earth. Using the right materials, and depending on what side of the equator you live, a compass can be created that will point in the direction of the magnetic field.
The materials needed to make a compass are:
- A sewing needle about one to two inches long
- A small bar magnet or refrigerator magnet
- A small piece of cork, like a wine bottle cork (not the plastic corks)
- A small glass or cup of water filled half-way
- A pair of pliers
- A pair of scissors (to cut the cork)
The directions for assembling the compass are:
- Rub the magnet over the needle a few times, always in the same direction, to magnetize the needle. It is important to rub it in the same direction, and not back and forth, so that one end of the needle is magnetized (Figure 1).
- Cut off a small circle (about 1/4 inch thick) from one end of the cork and lay the circle on a flat surface.
- Using a pair of pliers, push the magnetized needle through the cork so that equal portions of the needle are sticking out on either side of the cork. This is the compass.
- Gently place the compass (cork and needle assembly) into the half-filled cup or glass of water (Figure 2).
- Place the cup of water with the compass inside on a flat surface and watch the magnetized end of the needle point either towards the North Pole if in the Northern Hemisphere or towards the South Pole if in the Southern Hemisphere.
This can come in handy as an easy science experiment or an activity for children. Likewise, the materials needed are small and can be easily stored for emergencies in case of disorientation while boating or hiking.
Related Articles:
Source:
Discover Your World with NOAA: An Activity Book
Compton, Robert R., Geology in the Field. NY: John Wiley and Sons, 1985.
 |
 |
 |
