Heat

“ Whether that heat be, as some suppose, universal in the interior of the earth, or whether it be merely local at the several places where its manifestations are felt, is a matter which need not now concern us. All that is necessary for our present purpose is the admission that heat is present to some extent. ”

“ How is heat diffused through the atmosphere?
By convection. The warmth radiating from the surface of the earth warms the air in contact with it; the air expands, and becoming lighter, flies upwards, bearing with it the caloric which it holds, and diffusing it in its course. ”

“ The heat also of the world is more pure, clear, and lively, and, consequently, better adapted to move the senses than the heat allotted to us; and it vivifies and preserves all things within the compass of our knowledge. ”

“ That this heat is furnished by the air, he proves, by finding, that that which we inspire contains more heat than that which we expire, or than the aqueous humor which we expire along with it, in a very considerable proportion; so that if the heat contained in the pure air did not become latent in the blood, it would raise its temperature higher than that of red-hot iron. ”

“ Heat causes moisture to move, and cold arrests it; as is seen in a cold country which arrests the motion of the clouds in the air. Where there is life there is heat, where there is vital heat there is movement of moisture. ”

“ I mean, my dear, that everything contains heat.
Daughter. Everything contains heat, mother, did you say? Why, then, is not everything warm? Some things, mother, are very cold; as ice, and snow, and that marble slab.
Mother. Yes, my child, everything contains heat, as I shall presently show you. When Alice goes to make a fire in a cold day, she does not carry the heat with her, and put it into the fire, nor into the wood, nor the coal, does she? ”

“ That natural heat which exists from the sun of the world, serves spiritual heat for a receptacle, is manifest from the heat of the body, which is produced by the heat of its spirit and supplies the place thereof in the body. ”

“ You will then see, according as the day is warm or cold, that the air contracts under the action of cold, and expands under the action of heat; as will be seen by the water rising when the air contracts, and sinking when it dilates. But the air’s sense of heat and cold is so subtle and exquisite as far to exceed the perception of the human touch, insomuch that a ray of sunshine, or the heat of the breath, much more the heat of one’s hand placed on the top of the glass, will cause the water immediately to sink in a perceptible degree. ”

“ From the sense of heat, again, we naturally derive the idea of a continuous scale or order, expressed by such terms as summer heat, blood heat, fever heat, red heat, white heat, in which all bodies may be placed with regard to their degrees of hotness, and we speak of the temperature of a body as denoting its place in the scale, in contradistinction to the quantity of heat it may contain. ”

“ Heat may be separated from the smoke as well as from the light, by means of a plate of iron, which will suffer heat to pass through it without the others.
3. Fire sends out its rays of heat as well as rays of [228] light, equally every way; but the greatest sensible heat is over the fire, where there is, besides the rays of heat shot upwards, a continual rising stream of hot air, heated by the rays shot round on every side. ”

“ Again, the heat of the element of fire and, by day, the heat of the sun, have power to draw forth the moisture of the low parts of the mountains and to draw them up, in the same way as it draws the clouds and collects their moisture from the bed of the sea. ”

“ When there is heat, there is motion. No matter what motion it may be,—it all comes from heat, either directly from the sun's heat, or from the heat which the sun has prepared in the coal, the wood, the bread, and the grass. ”

“ Modern theory regards heat as a manifestation of motion, and experiment proves that a body falling through a certain space generates a definite quantity of heat, while observation shows that the waters at the base of the Falls of Niagara possess a temperature 1° higher than when they first glide over the edge of the precipice. ”

“ The heat radiated by the sun into the surrounding space on every side of it is another example of the same cooling process, a hot body giving up its heat to the colder space about it, and it is the minute fraction of this heat poured out by the sun, and in small part intercepted by the earth, which warms the latter and produces what we call weather, climate, the seasons, etc. ”

“ According to the materialistic view of heat, bodies are figured as sponges, and heat as a kind of fluid absorbed by them, different bodies possessing different powers of absorption. According to the dynamic view, as already explained, heat is regarded as a motion, and capacity for heat indicates the quantity of that motion consumed in internal changes. ”

“ Heat is of two kinds, and may be either apparent to our senses, and therefore called sensible heat; or it may be entirely concealed, although present in solids, liquids, and gases, and is then termed insensible or latent heat. ”

“ This internal heat, be it much or little, has obviously a different origin from the heat which we know on the surface. The heat we enjoy is derived from the sun. The internal heat cannot have been derived from the sun; its intensity is far too great, and there are other insuperable difficulties attending the supposition that it has come from the sun. ”

“ One of the results of the laws of heat, as they exist in the globe, is, that, by their action, the thermal state tends to a limiting condition, which, once reached, remains constant and steady, as it now is. ”

“ As the sun's heat is supposed to be in proportion to the intensity of his height, it is probable that a degree of heat so very intense would be sufficient to convert into vapour every terrestrial substance with which we are acquainted. ”

“ The Fahrenheit, which has got warmed up to temperate, rises to summer heat, and even a little above it. They enjoy each other's company mightily. To be sure, their scales differ, but have they not the same freezing and the same boiling point? ”

“ But concerning heat, how it is reckoned by the crowd of philosophizers, in natural philosophy and in materia medica to exert an attraction otherwise than nature allows, to which true attractions are falsely imputed, we will discuss more at length elsewhere, when we shall determine what are the properties of heat and cold. ”

“ The reason given is, that the land being heated heats the air, which rises and thus gives off much of the heat to space, while the same area covered with water would retain more of the heat, and by means of currents carry it to other parts of the earth's surface. ”

“ The approach toward a hot body increases heat in proportion to the approximation; a similar effect to that of light, for the nearer any object is placed toward the light, the more visible it becomes. 34. The union of different heats increases heat, unless the substances be mixed; for a large and small fire in the same spot tend mutually to increase each other's heat, but lukewarm water poured into boiling water cools it. 35. The continued neighborhood of a warm body increases heat. ”

“ The benignant vapours cool our climates in summer by rendering latent the excessive heat of the noonday sun; and they temper them in winter by rendering sensible and restoring again to the air, that self-same heat. ”

“ ELEMENTARY HEAT. Combined and sensible heat; chemical combinations attract heat, solutions reject heat; ice cools boiling water six times as much as cold water cools it; cold produced by evaporation; heat by devaporation; capacities of bodies in respect to heat, 1. Existence of the matter of heat shewn from the mechanical condensation and rarefaction of air, from the steam produced in exhausting a receiver, snow from rarefied air, cold from discharging an air-gun, heat from vibration or friction ”

“ Heat has been already mentioned as a general power, and as acting in all the different parts of the globe; I would now wish more particularly to call the attention of the reader to subterraneous fire, or heat, as a powerful agent in the mineral regions, and as a cause necessarily belonging to the internal constitution of this earth. ”

“ Instruments also which generate heat only by motion. And farther, places for strong insolations; [86] and again, places under the earth, which by nature, or art, yield heat. These divers heats we use, as the nature of the operation, which we intend, requireth. ”

“ As our earth is daily losing internal heat, or the equivalent of heat, it must have contained more heat yesterday than it does to-day, more last year than this year, more twenty years ago than ten years ago. ”

“ To analyze the concept of heat means to ascertain that which is common to all manifestations of heat.
The general nature of the thing is its true nature, [Pg 91] the general quality its true quality. We define rain more truly as being wet than as being fertilizing, because it gives moisture wherever it falls, while it fertilizes only under certain circumstances and in certain places. My true friend is one who is constant and loyal to me all my life under all circumstances. ”

“ Place a screen between you and a bright fire, and you will immediately feel that some of the heat from the fire place has been cut off. When the sun is shining, expose your hand to its beams for a time, and then hold a book between the hand and the sun. At first, your skin is warmed; but the moment you put it in the shade, it is cooled again. The book has cut off the heat which was passing directly from the sun to your hand. When the atmosphere is felt to be cold, something has come in the way to keep the sun’s heat from directly reaching us. ”

“ Different substances, independent of colour, have the property of parting with heat from their surfaces at different rates. Rough and porous surfaces radiate heat more rapidly than smooth ones, and are consequently reduced in temperature ”

“ These details are amply sufficient to demonstrate the manner in which heat is diffused through air, whilst the rarefication of the air by heat suggests the cause of those frightful storms of wind that rush from other and colder parts of the surface of the globe, to supply the void produced by the cooling and contraction of the enormous volumes of gaseous matter. ”

“ The first truth to be comprehended is, that all matter contains within its substance the power of creating heat—or as it may be expressed more plainly, solids, fluids, and gases contain what is termed latent or insensible heat, in contradistinction to the heat which is apparent when we touch a vessel containing warm water or approach a cheerful fire ”

“ The internal heat of the earth, the elevation and depression of its crust, its belchings forth of vapours, ashes, and lava, are its activities, in as strict a sense, as are warmth and the movements and products of respiration the activities of an animal. The phænomena of the seasons, of the trade winds, of the Gulf-stream, are as much the results of the reaction between these inner activities and outward forces, as are the budding of the leaves in spring and their falling in autumn the effects of the interaction between the organization of a plant and the solar light and heat. ”

“ The earth is subject to the influence of two different sources of heat. One, like the arterial blood, strikes from the centre to the circumference: this internal heat it is which has been stored up since the unknown epoch when our globe was nothing more than an incandescent nucleus, surrounded by condensable vapours. ”

“ After air, we consider those bodies to be most sensible of heat, which have been recently changed and contracted by cold, as snow and ice; for they begin to be dissolved and melt with the first mild weather. ”

“ No less certain is it that heat is the prime factor in those more gradual vertical movements of the land to which we have referred elsewhere, but in regard to the exact manner in which it acts we are very much in the dark. ”

“ For the heat, which perpetually passes and emanates from it, being mixed with that which preceded it, multiplies the whole. A fire, for instance, does not warm a room in half an hour as much as the same fire would in an hour. ”

“ This heat, though it produces little change on the temperature of the air which it traverses, affords us some compensation for the heat which we radiate to the heavens. At night, also, if the sky be overcast, some compensation will be made to us, both in the town and in the country, though in a less degree than during the day, as the clouds will remit towards the earth no inconsiderable quantity of heat. But on a clear night, in an open part of the country, nothing almost can be returned to us from above in place of the heat which we radiate upward. ”

“ Similarly air, although of the same temperature, as shown by the thermometer, will feel colder or warmer to us according to whether it is in motion or still; because when in motion it removes heat from our bodies quicker than when at rest, since more of it passes over our surface. ”

“ The same task is carried on by the working of sun-heat, as by the fire under a kettle. All day long in a warm climate the sun’s rays are busily at work, lifting from the ocean-surface a continuous stream of fine invisible vapour. ”

“ This heat Cavendish spoke of as being destroyed or generated, and this is in accordance with what we now know respecting the nature of heat, for when a body passes from the solid to the liquid, or from the liquid or solid to the gaseous, condition, a certain amount of work has to be done, and a corresponding amount of heat is used up in the doing of it. When the body returns to its original condition, the heat is restored, as when a heavy body falls to the ground, or a bent spring returns to its original form. ”

“ Id proportion as our heat-losses increase, while the creation of heat in our interior remains about the same, we feel the necessity of diminishing the rate at which the heat leaves our immediate neighborhood. ”