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
Because the air does not abstract the heat of the hand so rapidly as
the water did, and the change in the degree of rapidity with which the
heat is abstracted _produces a sensation of increased warmth_.
154. _Why do we see blocks of ice wrapped in thick flannel in summer
time?_
Because the flannel, being a non-conductor, prevents the _external
heat_ from _dissolving the ice_.
Flannel wrapped around a _warm_ body _keeps in its heat_; and
wrapped around a _cold_ body, prevents heat from _passing into it_.
155. _How do we know that air is not a good conductor of heat?_
Because, _in still air_, heat would travel to a given point much more
rapidly, and in greater intensity, through even an indifferent _solid
conductor_, than it would through the _air_.
156. _How do we know that water is not a good conductor of heat?_
Because in a deep vessel containing _ice_, and with heat applied at the
top, some portion of the water may be made to boil _before the ice,
which lies a little under the surface, is melted_.
[Verse: "As snow in summer, and as rain in harvest; so honour is not
seemly for a fool."--PROV. XXVI.]
157. _Why would you apply the heat at the top, in this experiment?_
Because in heating water it _expands and rises_. The boiling of water
is caused by the heated water _ascending from the bottom_, and the
colder water descending to occupy its place. If the heat were not
applied at the top, it would be distributed quickly by _convection_,
but not by _conduction_.
158. _Why are bottles of hot water, used as feet-warmers, wrapped in
flannel?_
Because the flannel, _being a bad conductor_, allows the heat to _pass
only gently_ from the bottle, and preserves the warmth for a _much
longer time_.
159. _Why are hot rolls sent out by the bakers, wrapped up in flannel?_
Because the flannel, _being a bad conductor_, does not _carry off
rapidly the heat of the rolls_.
160. _Why is it said that snow keeps the earth warm?_
Because snow is a _bad conductor_, and prevents the frosty air from
_depriving the earth of its warmth_.
161. _Why are snow huts which the Esquimaux build found to be warm?_
Because snow, _being a bad conductor_, keeps in _the internal heat of
the dwelling_, and prevents the _cold outer air from taking away its
warmth_.
162. _Why is snow, being composed of congealed water (and water being a
better conductor than air), so good a non-conductor?_
Because in the process of congealation it is frozen into crystalline
forms, which, being collected into a mass, form a woolly body, thus
proving the truthfulness of the Bible simile, which says, God "giveth
snow like wool."
[Verse: "He giveth snow like wool: he scattereth the hoar frost like
ashes."--PSALM CXLVII.]
[Illustration: CRYSTALS OF SNOW, AS SEEN THROUGH A MICROSCOPE. FIG. 1.]
163. _Why does it frequently feel warmer after a frost has set in?_