Happy Hamilton Day!

A relatively obscure Irish mathematician-

https://www.britannica.com/biography/William-Rowan-Hamilton

"Hamilton had a deep interest in the fundamental principles of algebra. His views on the nature of real numbers were set forth in a lengthy essay, “On Algebra as the Science of Pure Time.” Complex numbers were then represented as “algebraic couples”—i.e., ordered pairs of real numbers, with appropriately defined algebraic operations. For many years Hamilton sought to construct a theory of triplets, analogous to the couplets of complex numbers, that would be applicable to the study of three-dimensional geometry. Then, on October 16, 1843, while walking with his wife beside the Royal Canal on his way to Dublin, Hamilton suddenly realized that the solution lay not in triplets but in quadruplets, which could produce a noncommutative four-dimensional algebra, the algebra of quaternions. Thrilled by his inspiration, he stopped to carve the fundamental equations of this algebra on a stone of a bridge they were passing."

He should not be obscure to anyone who studied graph theory, as the "Hamiltonian circuit" is named after him.