Magnetic toy, 1765
This toy consisted of six hearts made from different metals: gold, silver, lead, tin, copper and iron. The gold heart is missing. All six were kept in a mahogany box. If the lid of the box is closed, and the ivory tube with the compass needle placed over the hearts, the needle moves to indicate the metal directly below it. This effect is caused by a magnet concealed within each heart.
© Science Museum/Science & Society Picture Library