Galileo Minimum & Maximum Thermometer - 25 cm Height - Handcrafted in Italy - Pewter
A reverent reproduction of an ancient measuring instrument, this large handcrafted pewter thermometer brings elegant classicism to your otherwise high speed digital day. The two classic scales of Fahrenheit and Celsius are used, allowing the minimum and maximum temperature of a set period of time to be recorded. Also, Cosi Tabellini have patented a special rotating section which makes reading the two different scales easier.
After the early Italian thermoscopes of Galileo and Santorio in the 17th Century, and then the developments by Fahrenheit and Celsius resulting in comparable and accurate sealed thermometers of the early 18th Century, which were the forerunners of the thermometers we are familiar with today, the late 18th Century saw temperature measurement evolve even further. It was at this time that both the lowest and the highest temperatures, the minimum AND the maximum, could be measured on the same instrument.
The "minimum and maximum" thermometer features a special marker that measures the minimum and maximum temperature of a day, month or year, - a set period of time given in the two most known scales: Celsius and Fahrenheit. Otherwise known as the Six's thermometer, this instrument is used to record the extremes of temperature at a location, and was invented by Englishman James Six in 1782, and the same basic design remains in use. This type of thermometer is particularly useful in horticulture and gardening.
It consists of a U-shaped glass tube with two separate temperature scales set along each arm of the U. The left arm is for recording the minimum temperature and the right is for the maximum temperature. The arms of the U-shaped tube end with sealed glass bulbs. The bulb at the top of the minimum reading scale arm is full of alcohol, measuring the temperature by the expansion and contraction of the liquid. The right-hand-side bulb at the top of the maximum reading scale arm contains alcohol and a bubble of low-pressure gas or alcohol vapour. This bulb accommodates the expansion or contraction in the other bulb as the alcohol responds to the external temperature, and allows the train of alcohol and mercury to freely move in the U-shaped tube as the temperature changes, because of the vacuum in the right-hand-side bulb, in the U-shaped tube.
The maximum and minimum readings are recorded by two small steel markers which are sprung into the capillary tube which allows them to slide, pushed by the mercury as temperatures fluctuate. If the temperature rises, the maximum scale marker will be pushed. If it falls, the moving mercury will push the minimum scale marker. As the temperature varies, the markers will remain in their positions unless the temperature becomes higher (for maximum) or lower (for minimum) than already recorded, in which case the relevant marker is pushed further. The markers thus record the furthest point reached by the mercury in each arm of the tube, and thereby the highest and lowest temperatures since the thermometer has last been reset.
Before a new maximum or minimum reading can be taken, the thermometer must be reset by moving the markers to the top of the mercury, usually by hand using a small magnet to slide them along the tube. Any change in temperature after that will push one of the markers along with it. If the markers are not reset, they will register maxima and minima only if they exceed the values already encountered. Usually this type of thermometer is reset every 24 hours to measure the diurnal temperature variation.
Size: 10.5 cm x 25 cm
Materials Used: Pewter, Glass
Designer: Alberto Tabellini
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100% Lead Free
All Cosi Tabellini Pewter is 100% lead-free, so it is totally food & drink safe, and is both EU and US FDA approved.
Cosi Tabellini pieces come gift-boxed with a guarantee card and instructions on how to care for pewter.