The German instrument maker Gabriel Daniel Fahrenheit (1686-1736) made the first reliable thermometers. The temperature scale he originated is named after him.

Born in Danzig on May 14, 1686, Gabriel Fahrenheit was the son of a well-to-do merchant. He lost both parents on the same day, Aug. 14, 1701, and was thereafter apprenticed to a shopkeeper in Amsterdam. After completing a term of 4 years there, he turned to physics and became an instrument maker and glassblower. Although he lived in Amsterdam most of his life, he traveled widely and spent considerable time in England, where he became a member of the Royal Society.

Fahrenheit completed his first two thermometers by 1714. They contained alcohol and agreed exactly in readings. The scale which was to bear Fahrenheit's name had not yet been calibrated, and many different scales were tried before he settled on one. He soon decided to replace the alcohol with mercury and...