Used with
permission of Maiken Naylor, University at Buffalo, Buffalo, NY, USA,
http://ublib.buffalo.edu/libraries/units/sel/exhibits/stamps
Sir William Rowan Hamilton (1805-1865) was an Irish mathematician who devised a non-commutative four-dimensional algebra of quaternions, or hypercomplex numbers. Their importance lay in their applications in geometry and mathematical physics, leading to vector theory.