This document discusses temperature and different types of thermometers. It defines temperature as the degree of hotness or coldness, which is measured using a thermometer. It describes how mercury thermometers work, using two fixed points of melting ice and steam to calibrate the scale. It provides a formula to calculate temperature from the lengths at different points on an uncalibrated thermometer. Lastly, it briefly introduces thermocouple thermometers, which use the voltage produced from joining two different metal wires to measure temperature differences.