Fahrenheit Perfects His Thermometer

May 1, 1714

Daniel Fahrenheit, a Danzig-born instrument-maker working in Amsterdam, developed a mercury thermometer of unprecedented precision, calibrating it against brine, ice water, and human blood. His scale, with its oddly specific zero, would become the English-speaking world's way of measuring the weather for centuries to come. Celsius would propose a rival scale three decades later, and the two have coexisted uneasily ever since.