Let’s take this one a step (or two) at a time. First there was the thermos cope (commonly known as the Galileo thermometer, after its inventor) in 1593, a device that could indicate a change in temperature but not quantify it.
A scale of measurement wasn’t included until 1612, when Satori Satori developed his air thermos cope. Mercury didn’t become part of the mix until 1714, when Daniel Gabriel Fahrenheit put it in a thermometer.
In 1724 he introduced his now widely adopted temperature scale based on the freezing point of water. Electric thermometers bypass the liquid and use a sensor—a thermostatic—that changes its resistance depending on the temperature.