Mercury-in-glass thermometer

The mercury-in-glass or mercury thermometer was invented by physicist Daniel Gabriel Fahrenheit in Amsterdam. It consists of a bulb containing mercury attached to a glass tube of narrow diameter; the volume of mercury changes with temperature. The space above the mercury may be filled with nitrogen gas or it may be at less than atmospheric pressure, a partial vacuum. In order to calibrate the thermometer, the bulb is made to reach thermal equilibrium with a temperature standard such as an ice/water mixture, with another standard such as water/vapour, the tube is divided into regular intervals between the fixed points. In principle, thermometers made of different material might be expected to give different intermediate readings due to different expansion properties; the application of mercury and Fahrenheit scale for liquid-in-glass thermometers ushered in a new era of accuracy and precision in thermometry, is still to this day regarded as one of the most accurate thermometers available. The thermometer was used by the originators of the Celsius scales.

Anders Celsius, a Swedish scientist, devised the Celsius scale, described in his publication The origin of the Celsius temperature scale in 1742. Celsius used two fixed points in his scale: the temperature of melting ice and the temperature of boiling water; this wasn't a new idea, since Isaac Newton was working on something similar. The distinction of Celsius was to use not that of freezing; the experiments for reaching a good calibration of his thermometer lasted for 2 winters. By performing the same experiment over and over again, he discovered that ice always melted at the same calibration mark on the thermometer, he found a similar fixed point in the calibration of boiling water to water vapour. At the moment that he removed the thermometer from the vapour, the mercury level climbed slightly; this was related to the rapid cooling of the glass. When Celsius decided to use his own temperature scale, he defined his scale "upside-down", i.e. he chose to set the boiling point of pure water at 0 °C and the freezing point at 100 °C.

One year Frenchman Jean-Pierre Christin proposed to invert the scale with the freezing point at 0 °C and the boiling point at 100 °C. He named it Centigrade. Celsius proposed a method of calibrating a thermometer: Place the cylinder of the thermometer in melting ice made of pure water and mark the point where the fluid in the thermometer stabilises; this point is the freeze/thaw point of water. In the same manner mark the point where the fluid stabilises when the thermometer is placed in boiling water vapour. Divide the length between the two marks into 100 equal parts; these points are adequate for approximate calibration but both vary with atmospheric pressure. Nowadays, the triple point of water is used instead of the freezing point. Before the discovery of the true thermodynamic temperature, the thermometer defined the temperature. In practice, several materials gave similar temperatures to each other and, when discovered, to the thermodynamic temperature. One special kind of mercury-in-glass thermometer, called a maximum thermometer, works by having a constriction in the neck close to the bulb.

As the temperature rises, the mercury is pushed up through the constriction by the force of expansion. When the temperature falls, the column of mercury breaks at the constriction and cannot return to the bulb, thus remaining stationary in the tube; the observer can read the maximum temperature over the set period of time. To reset the thermometer it must be swung sharply; this design is used in the traditional type of medical thermometer. A maximum minimum thermometer known as Six's thermometer, is a thermometer which registers the maximum and minimum temperatures reached over a period of time 24 hours; the original design contains mercury, but as a way to indicate the position of a column of alcohol whose expansion indicates the temperature. Mercury thermometers cover a wide temperature range from −37 to 356 °C; this introduction of an inert gas increases the pressure on the liquid mercury and therefore its boiling point is increased, this in combination with replacing the Pyrex glass with fused quartz allows the upper temperature range to be extended to 800 °C.

Mercury cannot be used below the temperature at which it becomes solid, −38.83 °C. If the thermometer contains nitrogen, the gas may flow down into the column when the mercury solidifies and be trapped there when the temperature rises, making the thermometer unusable until returned to the factory for reconditioning. To avoid this, some weather services require that all mercury-in-glass thermometers be brought indoors when the temper

HD 32518 b

HD 32518 b is an extrasolar planet which orbits the K-type giant star HD 32518, located 399.7 light years away in the constellation Camelopardalis. It has a minimum mass three times greater than Jupiter and orbits the intermediate-mass giant star at a distance of only 0.59 AU in a circular orbit. The orbit takes 10.35 months to complete one round trip around the star. This planet was detected by the radial velocity method on August 12, 2009. For the 100th anniversary of the IAU HD 32518 and the planet HD 32518b were selected NameExoWorlds campaigns for Germany; the approved name of the planet HD 32518 b is Neri, named after the river Neri in Ethiopia, which runs through parts of the Mago National park. The name was suggested by pupils of a physics course at the Max-Born-Gynasium in Neckargemünd

Bert Johnson (footballer)

William Herbert Johnson, was an English football player and influential coach who played as a wing half in the Football League. He played in both the 1946 FA Cup Final for Charlton Athletic. However, he is most noted as an influential coach at Leicester City under Matt Gillies, he was signed by Gillies as head scout in 1959, but soon become Gillies' assistant manager. He was influential in the signing of both Dave Gibson and Mike Stringfellow, both of whom would become key figure in Leicester's success during the 1960s. Johnson is credited as having come up with a tactical innovation of switching the positions of Frank McLintock and Graham Cross, upsetting the traditional 1-11 formation; this hugely influenced Liverpool manager Bill Shankly. Gillies said on the innovation: "confused opposition" as opposition players would be asked to mark "our number eight, so they thought Cross was their man, when McLintock had replaced him" as "players hadn't got beyond thinking about numbers then." Bert Johnson at Post War English & Scottish Football League A–Z Player's Database