Question

Q4. Use the internet and find out the thermometers which were used in
the past.On which principles were they based?What were their
advantages and disadvantages? Why are they not used
nowadays. Prepare a project report on the same. Class 7 th​

Answer 1

Answer:

The earliest thermal instruments were developed during the sixteenth and seventeenth centuries. These simple instruments were constructed so as to trap air in glass tubes with the open end of the tube submersed in a reservoir of water. These open thermometers were termed thermoscopes. In 1610, Galileo used wine instead of water and was one of the first to use an alcohol thermometer. It was, of course, found that when carrying such a device up a mountain to a different altitude that the level in the tube was affected by the changing atmospheric pressure. These devices illustrated changes in sensible heat, before the concept of temperature had been recognized. While it is sometimes claimed that Galileo was the inventor of the thermometer, what he actually produced was a thermoscope. He did discover that glass spheres filled with aqueous alcohol of different densities would rise and fall with changing temperature. Today, this is the principle of the Galilean thermometer, which is calibrated with a temperature scale.

The first illustration of a thermoscope showing a scale, which therefore can be described as a thermometer, was by Robert Fludd in 1638. However, around 1612, Santorio Santorio calibrated the tube and went on to attempt to measure human temperature with his thermoscope. At the end of the sealed tube, he had a bulb blown of the optimal size to be inserted in the mouth. The open end was submersed in fluid. As the air expanded due to the oral temperature, fluid was expelled from the tube. After a fixed period of time, the bulb was removed, the air cooled, causing the fluid to rise in the calibrated tube

Explanation: