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[pg 306] 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[pg 307] 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[pg 308] 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[pg 309] 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[pg 310] 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.
[pg 311]“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[pg 312] 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[pg 313] 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[pg 314] 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.
[pg 315]“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 [pg 316]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,[pg 317] 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[pg 318] 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[pg 319] 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.
