wWhen Gilbert used lodestone to make a simple compass, he realized the Earth's magnetic field caused the compass needle to swing north. bBefore Gilbert's discovery, people belieived that a start in the big dipper or iron= from capped mountains in the north attracted compass needles.
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インボックスを開き、確認リンクをクリックし、直されたテキストが戻ってきます。もっとメールを治すのに：
又は