William Rowan Hamilton was an Irish mathematician and physicist, born on August 4, 1805. He is best known for his work in classical mechanics and for developing the concept of quaternions, which are a type of mathematical notation used to represent three-dimensional rotations. Hamilton's contributions laid the groundwork for many areas of modern mathematics and physics. In addition to his work in mathematics, Hamilton was also a notable astronomer and made significant contributions to optics. He served as the Royal Astronomer of Ireland at the Dunsink Observatory, where he conducted research and published papers that advanced the understanding of celestial mechanics. Hamilton passed away on September 2, 1865.