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“Secure the two ends of the wire by double-pointed tacks. Place a small pocket compass upon the block thus wound, and turn the block until the coils of wire are parallel to the needle when the circuit is open. Then pass a current through the coil. The deflection of the needle is much stronger than before, although, owing to the weakening of the cell, the deflection falls off after a time.” — Avery, 1895


Elroy M. Avery School Physics (New York: Sheldon and Company, 1895) 439


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