It was once thought that cold radiated as well as heat. But a mass of ice can only be said to radiate cold, by its radiating heat in less abundance than that which is emitted from other bodies surrounding it. It is, therefore, incorrect to speak of the radiation of cold.
CHAPTER XI.
208. Why, if you hold a piece of looking-glass at an angle towards the sum, will light fall upon an object opposite to the looking-glass?
Because the rays of the sun are reflected by the looking-glass.
209. Why, when we stand before a mirror, do we see our features therein?
Because the rays of light that fall upon us are reflected upon the bright surface of the mirror.
210. Why, if a plate of bright metal were held sideways before a fire, would heat fall upon an object opposite to the plate?
Because rays of heat may be reflected in the same manner as the rays of light.