Here as he walked by on the 16th of October 1843 Sir William Rowan Hamilton in a flash of genius discovered the fundamental formula for quaternion multiplication i² = j² = k² = ijk = −1 & cut it on a stone of this bridge.

Photo of William Rowan Hamilton stone plaque
JP on Wikimedia Commons

Broom Bridge, Broombridge Road, Dublin

on 13 November 1958

Colour: stone

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