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
Medical thermometer There are factors that make readings of this thermometer to some extent unreliable, for example faulty placement in the external ear canal by the operator, and wax blocking the canal. Such error-producing factors usually cause readings to be below the true value, so that a fever can fail to be detected. A temporal artery thermometer, which uses the infrared principle report temperature, were not very accurate and therefore caution should be used. The band thermometer is applied to the patient's brow. It is typically a band coated with different temperature-sensitive markings using plastic strip thermometer or similar technology; at a