Joseph Rogerson Cotter, 1911 Encyclopædia Britannica, Volume 1… (1911)
“ If a luminous body is surrounded by empty space, the light which it emits suffers no loss of energy as it travels outwards. The intensity of the light diminishes merely because the total energy, though unaltered, is distributed over a wider and wider surface as the rays diverge from the source. ”
Joseph Rogerson Cotter, 1911 Encyclopædia Britannica, Volume 1… (1911)
“ A body which absorbs all radiations of all wave-lengths would be called a “perfectly black body.” No such body actually exists, but such substances as lamp-black and platinum-black approximately fulfil the condition. The fraction of the incident radiation which is not absorbed by a body gives a measure of its reflecting power, with which we are not here concerned. Most bodies exhibit a selective action on light, that is to say, they readily absorb light of particular wave-lengths, light of other wave-lengths not being largely absorbed. ”
Joseph Rogerson Cotter, 1911 Encyclopædia Britannica, Volume 1… (1911)
“ Even the most transparent bodies known absorb an appreciable portion of the light transmitted through them. Thus the atmosphere absorbs a part of the sun’s rays, and the greater the distance which the rays have to traverse the greater is the proportion which is absorbed, so that on this account the sun appears less bright towards sunset. ”
