William Thomson, Lord Kelvin (1824-1907) was a mathematical physicist and engineer. He did important work in the mathematical analysis of electricity and formulation of the first and second laws of thermodynamics, and did much to unify the emerging discipline of modern physics. Lord Kelvin is widely known for realizing that there was a lower limit to temperature, absolute zero; absolute temperatures are stated in units of kelvin in his honor. He also had a career as an electric telegraph engineer and inventor. He invented several instruments to improve navigation and safety. One notable example was a mariner's compass more accurate than any other in existence. This was later universally adopted.