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
Six's thermometer in the push-button type with the magnetic plate in place, there is a risk of damaging the weak magnet behind the scale, or magnetising the steel in the markers either weakening or enhancing the pulling force against the capillary tube on all or part of the scale so that the thermometer no longer works properly. The original Six's thermometer design contains mercury, which has been banned for most uses in the European Union and some other parts of the world. In 2006, S.Brannan & Sons Ltd, a UK company, was granted a patent for a mercury-free version of Six's maximum–minimum