What key mechanical innovation defined James Hargreaves' Spinning Jenny around 1764?

Answer

It mounted several spindles (typically eight) driven simultaneously by one large wheel.

The Spinning Jenny was ingenious because it allowed one worker to spin eight threads at once by mounting multiple spindles in a row, all driven by a single wheel, thus multiplying output immediately.

What key mechanical innovation defined James Hargreaves' Spinning Jenny around 1764?
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