Versorium

The versorium (Latin word for "turn around") was the first electroscope, the first instrument that could detect the presence of static electric charge.

The versorium needle also responds identically regardless of the polarity of the attracting charge, so it cannot distinguish between a positive and a negative charge, unlike a compass needle, which has a "North" and "South" end which can distinguish between the "North" and "South" pole of a magnet.

While he didn't devise a theory to explain his findings, it was a good example of how science was starting to change by incorporating empirical studies at the dawn of the Age of Reason.

[4] A century and a half later, Andrew Gordon constructed what seems to have been the first electric motor, which was based on Gilbert's device.

[5][6] One reason is that the operation of the versorium is simple to understand and the device is suitable for building by even young students, but can still be used to illustrate many important concepts in electricity.