The reason why : $b a careful collection of many hundreds of reasons for things which, though generally believed, are imperfectly understood. A book of condensed scientific knowledge for the million — John Stuart Mill — John Shaqi
The reason why : $b a careful collection of many hundreds of reasons for things which, though generally believed, are imperfectly understood. A book of condensed scientific knowledge for the million
John Stuart Mill · en
176. _Is the atmosphere ever as hot as the human body?_
Not in this country. On the hottest day it is 10 or 12 deg. _cooler
than the temperature of our bodies_.
177. _What is the highest degree of artificial heat which man has been
known to bear?_
A man may be surrounded with air raised to the temperature of 300 deg.
(the boiling point being 212), and yet not have the heat of his body
raised more than two or three degrees above its natural temperature of
from 97 deg. to 100 deg.
178. _Why may man endure this degree of heat for a short time without
injury?_
Because the skin, and the vessels of fat that lie underneath it, are
bad conductors of heat.
And because perspiration passing from the skin and evaporating, would
_bear the heat away_ as fast as it was received.
Because, also, the vital principle (life) exercises a mysterious
influence in the preservation of living bodies from physical influences.
179. _Is the air ever hot enough, in any part of the world, to destroy
life?_
Yes. The hot winds of the Arabian deserts, which are called _simooms_,
scatter death and desolation in their track, withering trees and
shrubs, and burying them under waves of hot sand. When camels see the
approach of a simoom they rush to the nearest tree or bush, or to some
projecting rock, where they place their heads in an opposite direction
to that from which the wind blows, and endeavour to escape its terrible
violence. The traveller throws himself on the ground on the lee side of
the camel, and screens his head from the fiery blast within the folds
of his robe. But frequently both man and beast _fall a prey to the
terrible simoom_.
180. _Why are these hot winds so terrible in their effects?_
Because, being in motion, they search their way to every part of the
body, and passing over it _leave some portion of their heat behind_,
which is again followed by _additional heat from every fresh blast of
wind_.
[Verse: "The fear of the Lord is the beginning of knowledge: but
fools despise wisdom and instruction."--PROVERBS I.]
CHAPTER IX.
181. _What is Radiation?_
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.
186. _What becomes of the heat that is radiated from one body to
another?_