10 Euros Sir William R. Hamilton

Issued to mark the bicentenary of Hamilton's birth, this coin commemorates the mathematician who, on 16 October 1843, carved the fundamental formula for quaternions into the stone of Brougham Bridge in Dublin during a flash of inspiration he had been chasing for over a decade. The Royal Irish Academy still holds his notebooks from that period.

Ireland has produced relatively few silver commemoratives in this format, and the Hamilton issue remains one of the more intellectually specific — honoring a figure whose work in non-commutative algebra underpins modern computer graphics and aerospace navigation, fields unimaginable in his lifetime.