ECONOMY OF HEAT.
"In this final lesson I wish," said Mr. Wilton, "to bring before you some
general views of the whole subject of the agency and management of heat.
"When Jesus had fed the five thousand men upon the mountain side by the
Sea of Galilee, he said to his disciples, 'Gather up the fragments that
remain, that nothing be lost.' The Christ who spoke these words was the
same Christ by whom 'all things were created that are in heaven and that
are in the earth, visible and invisible.' These words inculcate the
propriety of saving, the very opposite of extravagance and wastefulness.
The same prudent economy we find in all God's works. Nothing is wasted.
God provides bountifully; he is not stinted in his works; we find nothing
narrow or mean; his resources are ample for all his undertakings. Perhaps
a careless observer might charge him with prodigality and wastefulness.
The wilderness rejoices in beauty and fertility upon which no human eye
gazes, and which supplies no human want.
'Full many a gem of purest ray serene
The dark unfathomed caves of ocean bear;
Full many a flower is born to blush unseen,
And waste its sweetness on the desert air.'
Rich fruit grows ruddy and golden in the autumnal sun only to fall and
decay. How small a part of the seeds which might germinate and reproduce
the parent plant ever fulfill this their legitimate object! But this is
not waste. As for the beauty with which the unpeopled wastes are smiling,
we know not what other beings besides man 'grow glad at the sight.' Fruits
and grains and seeds were appointed as much to nourish the animal kingdom
as to reproduce plants and trees. And that which decays is not wasted. The
oak lifts high its leafy arms and does battle with the tempests for a
century, and then having served its purpose in Nature, if man does not
call it to the higher mission of serving his purposes, Nature begins to
pull down the structure she has reared and rebuild the elements in other
forms--such forms as man perchance may need. The fruit that falls and
decays is not wasted; it shall blush with golden tints in other forms and
in other years. God pulls down the old that he may build the new. The same
elements appear and reappear in a thousand shapes. There is endless
change, but no waste. This sentiment, 'Gather up the fragments, that
nothing be lost,' which is proclaimed throughout all Nature, is uttered
most emphatically in the management of heat. God has provided most
bountiful stores of heat, but has left no heat to go to waste. Will you,
Mr. Hume, suggest one of the general arrangements for the economical use
of heat?"
"I think that the arrangement for economizing heat which ought to be
mentioned first is the confinement of heat to the locality where it is
needed."
"Will you explain that a little farther, Mr. Hume?"
"All living creatures are confined near the surface of the earth. They
penetrate only a few feet into the earth and soar a few hundred feet above
it. Heat is therefore confined to the region of the earth's surface. It
penetrates but a little way below the surface, and when warm air rises
into the higher regions, heat becomes latent. The higher parts of the
atmosphere are cold, and in the empty spaces of the heavens the
temperature is we know not how low. God has provided for heating only that
part of the world which needs to be heated. I think you spoke of this in
some one of the earlier lessons."
"Perhaps I did. But I refer to it again to call especial attention to the
idea of the economical use of heat. Who will mention another method by
which heat is economized?"
No one answered.
"I asked the question, but did not expect an answer. God shows economy in
the use of heat by accomplishing many different results by its agency. I
do not mean that the same identical heat accomplishes different results at
the same time. The same force cannot accomplish two works. As man cannot
spend his money and at the same time keep it, no more can heat be used and
not used up in that form. The heat which raises the temperature can do
nothing else at the same time, and when it is employed as force it ceases
to affect temperature. But by this one agency of heat the Creator brings
very various works to pass. Heat expands bodies, relaxes cohesive
attraction, and brings the chemical affinities into activity. By this
means the elements of Nature are subdued to human uses, seeds germinate,
all the processes of vegetable life go on, and digestion and nutrition are
carried forward in the bodies of animals. By the agency of heat the winds
blow, the deep waters of the ocean circulate, clouds are formed, dew and
rain refresh the earth, rivers flow, and all the activities of life fill
the world. The employment of one agency for the accomplishment of so many
works indicates economy in the expenditure of force and means. Moreover,
the same heat appears and reappears again and again, passing from the
sensible to the latent form and back again, asserting itself alternately
in raising the temperature and as active force. A beam of heat falls upon
our world: it is partly absorbed by the earth, and warms it. A part of
that warmth is used in setting the chemical affinities in action in the
sprouting of seeds; a part warms the air by conduction; a part is
radiated, and being stopped by the vapor in the air, warms it; the heat
of the air is partly used in the evaporation of water: the vapor formed is
condensed and waters the earth, and gives out the heat by which it was
formed; that raises the temperature of the air; a part of it is used in
deoxidizing carbonic acid and building up the forests; the forest tree
falls by the woodman's axe, is burned for fuel, and gives out its heat
again, or if it falls and decays, the result is the same; the heat given
out by combustion cooks the laborer's dinner and warms his room, or it
goes out again, and is used in preparing food for the growing wheat; that
wheat is used for food, and by slow combustion in the blood the heat is
again evolved, the body is warmed, and the chemical operations of
digestion and nutrition are maintained; the heat is radiated or conducted
from the body into the atmosphere, and again raises the temperature and
goes to do other work. At last, so far as our earth is concerned, it
escapes into the stellar spaces, and goes to bless other worlds. In all
these operations no heat-force is frittered away and wasted and lost. This
is one of the accepted doctrines of physical science. Heat is used
bountifully, but economically and without waste.
"Even the inequalities and variations of temperature must be counted
economy in the use of heat. The heat of midday is not needed at all hours,
and therefore it is not always provided; the heat of summer is not always
useful, and is therefore not given; a higher temperature for a part of the
year and a part of the day is necessary, and is bestowed. The smallest
amount of heat is so disposed as to accomplish the largest result. Keep in
mind, then, the economical aspect of God's management of heat.
"I would also have you remember how few are the principles involved in all
the ways and means for transporting heat and equalizing temperature. All
the various phenomena which we have examined can be brought under two
general principles. The first principle or method is the heating and
cooling of bodies. Bodies absorb heat; they part with their heat by
conduction or radiation. If they are heated and cooled without change of
place, heat is transported in time, but not in place. If the body be
removed from one place to another between the heating and the cooling or
between the cooling and the heating, heat is transported in both time and
space. This applies alike to solids, liquids, and gases; each one is a
carrier of heat in proportion to its specific heat.
"The second principle or method is the transportation of heat by the
change of sensible to latent heat and its restoration to a sensible state.
Under this principle there are four cases:
"1. Heat is employed in the evaporation of liquids, and is restored again
to use as affecting temperature by the condensation of the vapor.
"2. Heat is employed in liquifying solids, and becomes latent thereby, and
returns to the sensible state when the liquid solidifies. These two
principles find their grandest application in the changes of water: of
this application I have chiefly spoken; but they apply also to other
bodies--to metals as well as to liquids.
"3. Heat is rendered latent in the expansion of gases from removal of
pressure, and latent heat becomes sensible by the compression of gases.
"4. Heat is employed in the deoxidation of carbonic acid or other
combinations of oxygen, and is evolved in combustion. While in the latent
condition, heat may be kept without loss for an unlimited period of time
or transported from equator to pole. By the various applications of these
two general principles, all the different methods of equalizing
temperature are determined.
"I would have you remember also that these processes for transporting heat
and modifying temperature are not confined to the regular changes of days
and seasons and the permanent differences of zones, but apply to every
possible difference of temperature. One minute the sun shines out in full
splendor; the next, a cloud hides his face and cuts off his fervent beams;
the methods employed to soften the heat of the one minute and the chill of
the next are the same which equalize the temperature of the seasons.
Evaporation carries off the heat from the seething tropics, evaporation
carries off the excess of heat from the bodies of animals and men. The
same methods are equally efficient upon the grandest and upon the smallest
scale.
"In this connection let me give one or two illustrations of the delicacy
with which general principles adapt themselves to the minutest
circumstances. When the earth is wet, it is fitting that evaporation
should go on rapidly and remove the excess of water, but when the ground
is drier, it is fitting that evaporation should be checked and the
remaining moisture spared. This result is secured not merely by the lack
of moisture at the surface, but also by the decreased capacity of the
earth for absorbing heat. A dark color absorbs heat more readily than a
lighter color, and the earth becomes, as a general rule, darker when wet;
and lighter when dry. Moist earth, therefore, receives heat more readily
than dry earth, and the excessive moisture is the more rapidly carried off
by evaporation.
"Another more interesting illustration is presented by the odor of
flowers. In its place I told you that watery vapor hinders the radiation
of heat from the earth. Dark heat is absorbed by it. The same is true of
other gases, and also of the odors of fragrant substances. A bed of
flowers fills the air around with odors. By these odors much of the heat
radiated by the earth is stopped. By this means the air around the
blooming flowers is warmed. The invisible fragrance raises the temperature
and secures for the blooming plants a more genial atmosphere. The Lord
provides for the flowers when most of all they need to be cherished by a
congenial warmth.
"This completes what I have to say to you upon the subject of heat. I
might have gone far more into particulars, and extended these lessons over
six months instead of three. We started with the design of finding out
whether the works of Nature have anything to say about a wise and good
Creator. We could not examine the whole circle of God's works, and
therefore chose a single department--that of heat. I will leave yourselves
to decide whether we have found marks of divine wisdom and goodness,
whether Nature has had anything to say to _us_ about a Creator."
"It seems to me," said Samuel, "that if the works of Nature do not show
God's goodness and wisdom, it would be hard to tell what works would show
them. I think I shall always, after this, look upon the earth and sky with
more interest than I have ever felt in them before; I shall always look
upon them as having something to do with God."
"We certainly ought," said Mr. Wilton, "to study Nature in such a manner
and with such a spirit that we shall be led to reverence and worship the
Creator. Some very good men are afraid of scientific study, as if there
were something in it to draw men from belief in the Scriptures and the
Jehovah revealed in them; and it cannot be denied that not a few
unbelievers have tried to find a foundation and a defence for their
infidelity in scientific studies; but such men are not made skeptics by
earnest and reverent study of God's works: they were unbelievers before
and aside from physical studies, and they only try to glorify their
rejection of the Bible and Christ by deifying science and the creation and
holding them up in opposition to inspired revelations. If ever you find
the works of God separating you from God, you may know at once that you
misunderstand those works or come to them with a wrong spirit. 'The
undevout astronomer,' it has been said, 'is mad,' and the same might, with
good reason, be said of every undevout student of physical science.
"In selecting heat for our examination, I did not take the only rich
department of Nature's works. The practical chemist would find a richer
and broader field of research, and so would the anatomist and animal
physiologist, the geologist, or the physical geographer. I purposely chose
a comparatively narrow field, in order that our course of study might not
become wearisome by its length. You will find ample scope in the fields of
natural science for your largest powers, and enough to carry your thoughts
reverently to the great Creator and Governor.
"In one respect the study of Nature resembles the study of the Sacred
Scriptures. It is a revelation; it is an embodiment of God's thoughts; in
it God has expressed himself; and Nature, by most suggestive symbols and
types, teaches much more moral truth and spiritual sentiment than some men
think. In the brute creation it gives us, in pantomime, all the virtues
and graces and all repulsive vices and cruel passions. To this book of
Nature we ought to come without prejudice, reverently inquiring what is
written therein. We must study it thoroughly and interpret it as we
interpret the written word, comparing Scripture with Scripture. It is a
great attainment to be able to read and understand the thoughts of God
embodied in his works.
"In another respect, the book of Nature and the Sacred Scriptures have
very little in common. The Bible is occupied pre-eminently with moral
duties and spiritual relationship. Its great themes are sin and salvation.
Christ is the great central truth. One might compare the Scriptures to a
picture in which one central figure seizes every eye, and by whose
radiance the whole picture is filled with light, and that central figure
is Christ; or we might compare the Bible to a sublime oratorio, the
glorious symphony of the ages; through it all is heard one strain, sweetly
exultant as angel voices, faintly heard at first amid the sadness of the
fall, but rising still above the terrific bass of Sinai and its
ever-repeating echoes, growing more clear and strong upon the harps of the
prophets, till its rapturous beauty pours itself triumphant along the
plains of Bethlehem. In this revelation of salvation from the guilt and
ruin of sin the Bible stands alone. Upon this subject Nature is silent.
Salvation by Christ is the gem enshrined in the Scriptures. But what is
the setting for this gem? The works of God on the earth and in the
heavens. The prophets were men in sympathy with Nature. How David sung the
praises of the divine handiwork!--'O Lord, how manifold are thy works; in
wisdom hast thou made them all.' 'The heavens declare the glory of God
and the firmament showeth his handiwork. Day unto day uttereth speech, and
night unto night showeth knowledge. There is no speech nor language where
their voice is not heard.' How Christ unfolded the deepest spiritual
truths by the symbols of Nature! But if the casket be so worthy, what
shall be said of the gem which is enshrined within? That is the pearl of
great price. To that book which speaks in no doubtful voice of deliverance
from sin let us turn with increasing reverence; and above all, let us come
to him who came to reveal our God, who came to be as well as to make a
revelation of God, being himself 'the brightness of his glory and the
express image of his person.' I am glad that you all now feel that you
know him whom to know is everlasting life."
From these words of Mr. Wilton you will conclude that Ansel has at length
found rest in Christ. In another brief chapter I will tell you of his
experience, and then bid you adieu.