This document discusses heat, temperature, and thermometers. It defines heat as the transfer of kinetic energy, while temperature refers to the average kinetic energy of particles in a system. A mercury thermometer works by measuring the expansion and contraction of mercury in response to temperature changes. Its construction involves filling a glass tube with mercury and marking a scale. Fixed points are determined by placing the thermometer in melting ice or steam. Common temperature scales relate measured values to the freezing and boiling points of water.