Why Is Fire Hot?
When a fire is lighted it throws off what we call heat rays or waves. These waves are very much like the waves of light which come from a light or fire or the air waves which produce sounds. The rays of light and heat which come from the sun are like the rays of light and heat from a fire. Heat is of two kinds—heat proper which is resident in the body, and radiant heat which is the kind which comes to us from the sun or from a fire. This radiant heat is not heat at all, but a form of wave motion thrown out by the vibrations in the ether. The heat we feel is the sensation produced upon our skins when it comes in contact with the waves created by the fire. Heat was formerly thought to be an actual substance, but we know now that radiant heat is known to be the energy of heat transferred to the ether which fills all of space and is in all bodies also. The hot body which sets the particles of either in vibration and this vibrating motion in the form of waves travels in all directions. When these vibrations strike against our skin they produce a heat sensation; striking other objects these vibrations may produce instead of a heat sensation, either chemical action or luminosity. This is determined by the length of the vibratory rays in each case.