Tuesday, 28 May 2013

Club Day. The Birds of Prey version.

Oh, I am so glad that we had an opportunity to test-drive today's Birds of Prey navigation-themed project before the Club actually showed up. 

I've been so excited and pleased with the projects in Tools of Navigation that I had great expectations for the homemade compass project described in the book.  It's a dry compass, which I had difficulty finding projects and instructions for making on the Internet.  The premise is that a milk carton bottom serves as the box that the compass resides in.  A heavy paperclip is magnetized, then sandwiched between two circular pieces of paper (one a cardboard and the other plain printer paper), which forms the compass rose.  Lastly, the rose balances on a nail or screw that comes up through the bottom of the milk carton.

Our problems began early during our experiments.  The book specified that the nail should be steel and not iron, presumably because the nail should not be attracted to the magnetized paperclip in the rose.  As I dug through the containers of nails and screws in our garage, I discovered that they were all attracted to magnets.  An internet search revealed that plain old steel will usually be attracted to magnets, but certain types of stainless steel will not.  My husband wound up finding five stainless steel screws in the basement, and my dad supplemented our collection.

Then we tried to build the contraption.  We found it extremely tricky to balance the rose on the screw, even before trying to sandwich the magnetized paperclip, and I expect that it wouldn't have stayed in place with the slightest movement or gentle breeze.  After three attempts, we decided to ditch the dry compass and went with a tried and true do-it-yourself water compass project.

The water compass project is quite easy, and there are may sources on the internet for finding instructions for how to do it.  The materials needed were simple - a circular piece of cork, a needle, a magnet, and something to hold water.  We cut up a few corks we happened to have handy to serve as our compass rose.  Then we magnetized a sewing needle by running a magnet over it for several minutes.  Lastly, we used the bottoms of the milk containers that we were planning to use for the dry compasses to hold the water.  The magnetized needle was then inserted through the side of the cork, and then the cork and needle was placed in the water.

I read a bit of the history and science of compasses to the Club as they magnetized their needles (from Tools of Navigation).  Did you know that while the Chinese invented the first compass (in 210 BCE), they didn't actually use it for navigation?  Instead, it was used in feng shui.  In fact, the first known recorded use of a compass for navigation in the western culture wasn't until the 1100's CE. 

We learn something new every day, don't we?

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