Meteorology known as the first "anemometer". In 1607, Galileo Galilei constructed a thermoscope. In 1611, Johannes Kepler wrote the first scientific treatise on snow crystals: "Strena Seu de Nive Sexangula (A New Year's Gift of Hexagonal Snow)". In 1643, Evangelista Torricelli invented the mercury barometer. In 1662, Sir Christopher Wren invented the mechanical, self-emptying, tipping bucket rain gauge. In 1714, Gabriel Fahrenheit created a reliable scale for measuring temperature with a mercury-type thermometer. In 1742, Anders Celsius, a Swedish astronomer, proposed the "centigrade" temperature scale, the predecessor of the current Celsius scale. In 1783, the first hair hygrometer was demonstrated by
Mercury-in-glass thermometer drops to may be used. , many mercury-in-glass thermometers are used in meteorology; however, they are becoming increasingly rare for other uses, as many countries banned them for medical use due to the toxicity of mercury. Some manufacturers use galinstan, a liquid alloy of gallium, indium, and tin, as a replacement for mercury. The typical "fever thermometer" contains between of elemental mercury. Swallowing this amount of mercury would, it is said, pose little danger but the inhaling of the vapour could lead to health problems. In February 2009, the Argentine Health Ministry instructed by resolution 139/09 that all health centres