The radiation of heat is a motion of the particles, in a series of rays, diverging in every direction from a heated body.
182. What is this phenomena of Radiation understood to arise from?
From a strongly repulsive power, possessed by particles of heat, by which they are excited to recede from each other with great velocity.
183. What is the greatest source of Radiation?
The sun, which sends forth rays of both light and heat in all directions.
184. When does a body radiate heat?
When it is surrounded by a medium which is a bad conductor.
185. When we stand before a fire, does the heat reach us by conduction or by radiation?
By radiation.