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Ellen McCallie's Diary

Day 27: Altimeter

Photo: Black sand beachToday, Jonathan and I helped Kathy collect black sand, which we assume has tiny gold flakes in it, from a beach. It was almost disastrously funny though. When we hit the beach, we quickly found it covered in pebbles and rocks. As it turns out, the weather changed last night and what is normally a black sand beach with some rock and gravel became a pebble beach. Thankfully, we were able to find two good patches of black sand far down the beach. I was amazed that our plastic buckets didn't fall apart under the weight.

Basically, black sand is high in iron which is dense, thus it is heavy per unit size. Most, if not all, white sand is made of silica which is not so dense, thus is not so heavy per unit size.

Photo:The team inspects the treasure mapWhile we helped Kathy, Jonathan and I got on with our discussions about how to measure change in altitude in order to retrieve the treasure. As it turns out, the map we received was a bit misleading, so we asked for another one! We should have an updated version tomorrow so that we can build a useful altimeter using the same equipment one would use to make a barometer. The basic difference between the two is that a barometer is stationary and is designed to measure pressure changes that occur as weather changes. With the kind of altimeter we're making, we need the weather to stay constant so we can measure the natural changes in pressure as altitude changes. How fun!

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Photo: Ellen McCallie
Metal Detector Interactive