The invention of the thermoscope.

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A thermoscope is an instrument that shows changes in the temperature of a substance by noting changes in the volume of the substance[1].


It was Galileo Galilei, Italian astronomer, physicist and engineer, who built the first “working thermoscope” in 1593 C.E., albeit it was inaccurate and performed poorly, to the extent that he himself referred to it as nothing more than a toy[2]. The photograph[3] below is essentially what his thermoscope looked like; a small vase filled with water, attached to a thin vertically rising pipe, with a large empty glass bulb at the top[4].

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Changes in temperature of the upper bulb would exert positive or vacuum pressure on the water below, brought about by the expansion or contraction of air depending on whether there is a rise or fall in the surrounding temperature. Thereby causing the water to rise or lower in the thin column, as shown in the image[5] below:

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Higher temperature as air expands and pushes the water in the tube downwards.



Here is a portrait[6] of Galileo Galilei:

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  2. 340793/File/curriculum%20updates/ELA/DOQ/Unit%204%20Benchmark%207.16.pdf
  3. des_Arts_et_M%C3%A9tiers_thermoscope_de_galil%C3%A9e_1592.JPG
  5. Thermoscope.svg