IT will be convenient to consider different bodies in the solar system, and to study them with the special object of ascertaining4 what information they afford as to the great celestial5 evolution. We cannot hesitate as to which of the bodies should first claim our attention. Not on account of the predominant importance of our sun to the inhabitants of the earth, but rather because the sun is nearly a thousand times greater than the greatest of the planets, do we assign to the great luminary6 the first position in this discussion.
The sun is, indeed, especially instructive on the 76subject with which we are occupied. By reason of its great mass, the process of evolution takes place more slowly in the sun than in the earth or in any other planet. Evolution has, no doubt, largely transformed the sun from its prim7?val condition, but it has not yet produced a transformation8 so radical9 as that which the earth and the other planets have undergone. On this account the sun can give us information about the process of evolution which is not to be so easily obtained from any of the other heavenly bodies. The sun can still exhibit to us some vestiges10, if we may so speak, of that great prim?val nebula11 from which the whole system has sprung.
The heat of the sun is indeed one of the most astonishing conceptions which the study of Nature offers to us. Let me try to illustrate12 it. Think first of a perfect modern furnace in which even steel itself, having first attained13 a dazzling brilliance14, can be further melted into a liquid that will run like water. Let us imagine the temperature of that liquid to be multiplied seven-fold, and then we shall obtain some conception of the fearful intensity15 of the heat which would be found in that wonderful celestial furnace the great sun in the heavens.
Ponder also upon the stupendous size of that orb16, which glows at every point of its surface with the astonishing fervour that this illustration suggests. The earth on which we stand is a mighty17 globe; yet what are the dimensions of our earth in comparison with those of the sun? If we represent the earth by a grain of mustard seed, then on the same scale the sun should be represented by a cocoanut. We may perhaps obtain a more impressive conception 77of the proportions of the orb of day in the following manner. Look up at the moon which revolves18 round the heaven, describing as it does so majestic19 a track that it is generally at a distance of two hundred and forty thousand miles from the earth. Yet the sun is so large that if there were a hollow globe equally great, and the earth were placed at its centre, the entire orbit of the moon would lie completely within it.
Every portion of that stupendous desert of flame is pouring forth20 torrents21 of heat. It has, indeed, been estimated that the heat which issues from an area of two square feet on the sun would more than suffice, if it could be all utilised, to drive the engines of the largest Atlantic liner between Liverpool and New York.
This solar heat is scattered22 through space with boundless23 prodigality24. No doubt the dwellers25 on the earth do receive a fair supply of sunbeams; but what is available for the use of mankind can be hardly more than an infinitesimal fraction of what the sun emits. We shall scarcely be so presumptuous26 as to suppose that the sun has been designed solely27 for the benefit of the poor humanity which needs light and warmth. The heat and light daily lavished28 by the sun would suffice to warm and to illuminate30 two thousand million globes, each as great as the earth. If, indeed, it were true that the only object of the sun’s existence was to cherish this immediate31 world of ours, then all we can say is that the sun carries on its business in a most outrageously32 wasteful33 manner. What would be thought of the prudence34 of one who, having been endowed with a fortune of ten million pounds, spent one single penny of that vast sum in a profitable manner and dissipated 78every other penny and every other pound of his fortune in aimless extravagance? But this is apparently35 the way in which the sun manages its affairs, so far as our earth is concerned. Out of every ten million pounds worth of heat issuing from the glorious orb of day, we on this earth secure one pennyworth, and all but that solitary36 pennyworth seems to be utterly37 squandered38. We may say it certainly is squandered so far as humanity is concerned. What, indeed, its actual destination may be science is unable to tell.
And now for the great question as to how the sun’s heat is sustained. How is it that this career of tremendous prodigality has not ages ago been checked by absolute exhaustion39? Every child knows that the fire on the hearth40 will go out unless coal be provided. The workman knows that his devouring41 furnace in the ironworks requires to be incessantly42 stoked with fresh supplies of fuel. How, then, comes it that the wonderful furnace on high can still continue, as it has continued for ages, to pour forth its amazing stores of heat without being exhausted43?
Professor Langley has supplied us with an admirable illustration showing the amount of fuel which would be necessary, if indeed it were by successive additions of fuel that the sun’s heat was sustained. Suppose that all the coal-seams which underlie44 England and Scotland were made to yield up their stores; that the vast coalfields in America, Australia, China, and elsewhere were compelled to contribute every combustible45 particle they contained; suppose, in fact, that we extracted from this earth every ton of coal which it possesses in every isle46 and every continent; suppose that this mighty store of fuel, sufficient to supply all 79the wants of the earth for centuries, were to be accumulated, and that by some mighty effort that mass were to be hurled47 into the sun and were forthwith to be burnt to ashes; there can be no doubt that a stupendous quantity of heat would be produced. But what is that heat in comparison, we do not say with the heat of the sun, but with the daily expenditure48 of the sun’s heat? How long, think you, would the combustion of so vast a mass of fuel provide for the sun’s expenditure? We are giving deliberate expression to a scientific fact when we say that a conflagration49 which destroyed every particle of coal contained in this earth would not generate as much heat as the sun lavishes50 in the tenth part of every single second. During the few minutes that you have been reading these words a quantity of heat has gone for ever from the sun which is five thousand times as great as all the heat that ever has been or ever will be produced by the combustion of the coal that this earth has furnished.
But we have still another conception to introduce before we can appreciate the full significance of the sun’s extraordinary expenditure of heat and light. We have been thinking of the sun as it shines now; but as the sun shines to-day, so it has shone yesterday, and so it shone a hundred years ago, a thousand years ago; so it shone in the earliest dawn of history, so it shone during those still remoter periods when great animals flourished which have now vanished for ever; so the sun shone during those remote ages when life began to dawn on an earth which still was young. We do not, indeed, say that the intensity of the sunbeams has remained actually uniform throughout a period so vast; but there is every reason to believe that throughout these 80illimitable periods the sun has expended51 its radiance with the most lavish29 generosity52.
A most important question is suggested by these considerations. The consequences of frightful53 extravagance are known to us all; we know that such conduct tends to bankruptcy54 and ruin; and certainly the expenditure of heat by the sun is the most magnificent extravagance of which our knowledge gives us any conception. Accordingly, the important question arises: As to how the consequences of such awful prodigality have been hitherto averted55. How is it that the sun is still able to draw on its heat reserve, from year to year, from century to century, from ?on to ?on, ever squandering56 two thousand million times as much heat as that which genially57 warms our temperate58 regions, as that which draws forth the exuberant59 vegetation of the tropics or which rages in the desert of Sahara? That is the great problem to which our attention has to be given.
We must first ascertain3, with such precision as the circumstances permit, the actual amount of heat which the sun pours forth in its daily radiation. The determination of this quantity has engaged the attention of many investigators60, and the interpretation61 of their results is by no means free from difficulty. It is to be observed that what we are now seeking to ascertain is not exactly a question of temperature, but of something quite different. What we have to measure is a quantity of heat, which is to be expressed in the proper units for quantities of heat. The unit of heat which we shall employ is the quantity of heat necessary to raise one pound of water through one degree Fahrenheit62.
The solar constant is the number of units of heat 81which fall, in one minute, on one square foot of a surface placed at right angles to the sun’s rays, and situated63 at the mean distance of the earth from the sun. We shall suppose that losses due to atmospheric64 absorption have been allowed for, so that the result will express the number of units of heat that would be received in one minute on a square foot turned directly to the sun, and at a distance of 93,000,000 miles.
(Royal Observatory66, Greenwich.)
(From the Royal Astronomical67 Society Series.)
This is a matter for determination by actual observation and measurement. Theory can do little more than suggest the precautions to be observed and discuss 82the actual figures which are obtained. There have been many different methods of making the observations, and the results are somewhat various, but the discrepancies68 are not greater than might be expected in an investigation69 of such difficulty. The mean value which has been arrived at is fourteen, and the fundamental fact with regard to the solar radiation which we are thus enabled to state is that an area of a square foot exposed at right angles to the solar rays, at a distance of 93 millions of miles, will in each minute receive from the sun as much heat as would raise one pound of water fourteen degrees Fahrenheit.
It follows that the total radiation from the sun must suffice to convey, in each minute, to the surface of a sphere whose radius70 is 93,000,000 miles, fourteen units of heat per square foot of that surface. This radiation comes from the surface of the sun. It is easily shown that the heat from each square foot on the sun will have to supply an area of 46,000 square feet at the distance of the earth. Hence the number of units of heat emerging each minute from a square foot on the sun’s surface must be about 640,000.
We can best realise what this statement implies by finding the amount of coal which would produce the same quantity of heat. It can be shown that the heat given out by each square foot of the solar surface in one minute will be equivalent to that produced in the combustion of forty-six pounds of coal. If the sun’s heat were sustained by combustion, every part of the sun’s surface as large as the grate of an ordinary furnace would have to be doing at least one hundred times as much heating as the most vigorous stoking could extract from any actual furnace.
83The radiation of heat from a single square foot of the solar surface in the course of a year must, therefore, be equivalent to the heat generated in the combustion of 11,000 tons of the best coal. If we estimate the annual coal production of Great Britain at 250,000,000 tons, we find that the total heat which this coal can produce is not greater than the annual emission71 from a square of the sun’s surface of which each side is fifty yards. All the coal exported from England in a year does not give as much heat as the sun radiates in the same time from every patch on its surface which is as big as a croquet ground.
There is perhaps no greater question in the study of Nature than that which enquires72 how the sun’s heat is sustained so that the radiation is still dispensed73 with unstinted liberality. If we are asked how the sun can be fed so as to sustain this expenditure, we have to explain that the sun is not really fed. If, then, it receives no adequate supplies of energy from without, we have to admit that the sun must be getting exhausted.
I ought, indeed, to anticipate objection by at once making the admission that the sun does receive some small supply of energy from the meteors which are perennially74 drawn75 into it. The quantity of energy they yield is, however, insignificant76 in comparison with the solar expenditure of heat. We may return to this subject at a later period, and it need not now receive further attention.
We must deliberately77 face the fact that the energy of the sun is becoming exhausted. But the rate of exhaustion is so slow that it affords no prospect78 of inconvenience to humanity; it does not excite alarm. 84We grant that we are not able to observe by instrumental means any perceptible diminution79 of solar energy. Still, as we know that energy is being steadily80 dissipated from the sun, and that energy cannot be created from nothing, it is certain the decline is in progress. But the reserve of energy which the sun possesses, and which can be ultimately rendered available to sustain the radiation, is so enormous in comparison with the annual expenditure of energy, that myriads81 of centuries will have to elapse before there is any appreciable82 alteration83 in the effectiveness of the sun.
Let me illustrate the point by likening the sun to a grain warehouse, in which 2,500 tons of wheat can be accommodated. Let us suppose that the warehouse was quite full at the beginning, and that the wheat was to be gradually abstracted, but only at the rate of one grain each day. Let us further suppose that no more wheat is to be added to that already in the warehouse, and let us assume that the wheat thus stored away experiences no deterioration84 and no loss whatever except by the removal of one grain per diem. It is easy to see that very many centuries would have to elapse before the grain in that warehouse had decreased to any appreciable extent.
With a consumption at the rate of a single grain a day a ton of corn would last about four thousand years, and 2,500 tons of corn would accordingly last about ten million years. It follows, therefore, that if the grain in that store were consumed at the rate of only one grain per day the warehouse would not be emptied for ten million years.
85
II. Spectrum of Arcturus.
(Professor H. C. Lord.)
The quantity of heat, or rather the reserve of energy equivalent to heat, which still remains86 stored up in the sun bears to the quantity of heat which the sun radiates away in a single day a ratio something like that which a single grain of corn bears to 2,500 tons of corn.
The sun’s potential store of heat is no doubt very great, though not indefinitely great. That heat is beyond all doubt to be ultimately exhausted; but the reserve is so prodigious87 that for the myriads of years during which the sun has been subjected to human observation there has been no appreciable alteration in the efficiency of radiation.
It might be supposed that the sun was merely a white-hot globe cooling down, and that the solar radiation was to be explained in this way. But a little calculation will prove it to be utterly impossible that the heat of the great luminary could be so accounted for. A knowledge of the current expenditure of solar heat shows that if the sun had been a globe of iron at its fusing point, then at the present rate of radiation 86it would have sunk to the temperature of freezing water in forty-eight years.
Perhaps I ought here to explain a point which might otherwise cause misapprehension. For our ordinary sources of artificial heat we, of course, employ some form of combustion. Whenever combustion takes place there is chemical union between the carbon or other fuel, whatever it may be, and the oxygen of the atmosphere. A certain quantity of carbon enters into chemical union with a definite quantity of oxygen, and, as an incident in the process, a definite quantity of heat is liberated88. So much coal, for instance, requires for complete combustion so much air, and, granted a sufficiency of air, the union of the carbon and hydrogen in the coal will give out a certain quantity of heat which may be conveniently expressed by the number of pounds of water which that heat would suffice to transform into steam. It is necessary to observe that there are definite numerical relations among these quantities. The quantity of heat that can be produced by the combustion of a pound of any particular substance will depend upon the nature of that substance.
As chemical combination is the main source of the artificial heat which we employ for innumerable purposes on the earth, it seems proper to consider whether it can be any form of chemical combination which constitutes the source of the heat which the sun radiates in such abundance. It is easy to show that the solar radiation cannot be thus sustained. The point to which I am now referring was very clearly illustrated89 by Helmholtz in a lecture he delivered many years ago on the origin of the planetary system.
87To investigate whether the solar heat can be attributed to chemical combination, we shall assume for the moment that the sun is composed of those particular materials which would produce the utmost quantity of heat for a given weight; in other words, that the sun is formed of hydrogen and oxygen in quantities having the same ratio as that in which they should be united to form water. The quantity of heat generated by the union of known weights of oxygen and hydrogen has been ascertained90, by experiments in the laboratory, to exceed that which can be generated by corresponding weights of any other materials. We can calculate how much of the sun’s mass, if thus constituted, would have to enter into combination every hour in order to generate as much heat as the hourly radiation of the sun. We need not here perform the actual calculation, but merely state the result, which is a very remarkable91 one. It shows that the heat arising from the supposed chemical action would not suffice to sustain the radiation of the sun at its present rate for more than 3,000 years. Thirty centuries is a long time, no doubt, yet still we must remember that it is no more than a part even of the period known to human history. If, indeed, it had been by combustion that the sun’s heat was produced, then from the beginning of the sun’s career as a luminous92 object to its final extinction93 and death could not be longer than 3,000 years, if we assumed that its radiation was to be uniformly that which it now dispenses94.
But it may be said that we are dealing95 only with elements known to us and with which terrestrial chemists are familiar, and it may be urged that the 88sun possibly contains materials whose chemical union produces heat in much greater abundance than do the elements with which alone we are acquainted. But this argument cannot be sustained. One of the most important discoveries of the last century, the discovery which perhaps more than any other has tended to place the nebular theory in an impregnable position, is that which tells us that the elements of which the sun is composed are the same as the elements of which our earth is made. We shall have to refer to this in detail in a later chapter. We now only make this passing reference to it in order to dismiss the notion that there can be unknown substances in the sun whose heat of combustion would be sufficiently96 great to offer an explanation of the extraordinary abundance of solar radiation.
There is nothing more characteristic of the physical science of the century just closed than the famous discovery of the numerical relation which exists between heat and energy. We are indebted to the life-long labours of Joule, followed by those of many other investigators, for the accurate determination of the fundamental constant which is known as the mechanical equivalent of heat. Joule showed that the quantity of heat which would suffice to raise one pound of water through a single degree Fahrenheit was the precise equivalent of the quantity of energy which would suffice to raise 772 pounds through a height of one foot. It would be hard to say whether this remarkable principle has had a more profound effect on practical engineering or on the course of physical science. In practical engineering, the knowledge of the mechanical equivalent of heat will show the engineer 89the utmost amount of work that could by any conceivable apparatus97 be extracted from the heat potentially contained in a ton of coal. In the study of astronomy the application of the same principle will suffice to explain how the sun’s heat has been sustained for illimitable ages.
Fig. 16.—Brooks’ Comet and Meteor Trail.
(November 13th, 1893. Exposure 2 hours.)
(Photographed by Professor E. E. Barnard.)
It will be convenient to commence with a little calculation, which will provide us with a result very instructive when considering celestial phenomena98 in connection with energy. We have seen that the unit of heat—for so we term the quantity of heat necessary to raise a pound of water one degree—will suffice, when transformed into mechanical energy, to raise 772 pounds through a single foot. This would, of course, be precisely99 the same thing as to raise one pound through 772 feet. Suppose a pound weight were carried up 90772 feet high and were then allowed to drop. The pound weight would gradually gather speed in its descent, and, at the moment when it was just reaching the earth, would be moving with a speed of about 224 feet a second. We may observe that the work which was done in raising the body to this height has been entirely100 expended in giving the body this particular velocity101. A weight of one pound, moving with a speed of 224 feet a second, will therefore contain, in virtue102 of that motion, a quantity of energy precisely equivalent to the unit of heat.
It is a well-known principle in mechanics that if a body be dropped from any height, the velocity with which it would reach the ground is just the velocity with which the body should be projected upwards103 from the ground in order to re-ascend104 to the height from which it fell (the resistance of the air is here overlooked as not having any bearing upon the present argument). Thus we see that a weight, moving with a velocity of 224 feet per second, contains within itself, in virtue of its motion, energy adequate to make it ascend against gravity to the height of 772 feet. That is to say, this velocity in a body of a pound weight can do for the body precisely what the unit of heat can do for it; hence we say that in virtue of its movement the body contains a quantity of energy equal to the energy in the unit of heat.
Let us now carry our calculation a little further. If a pound of good coal be burned with a sufficient supply of oxygen, and if every precaution be taken so that no portion of the heat be wasted, it can be shown that the combustion of the coal is sufficient to produce 14,000 units of heat. In other words, the 91burning of one pound of coal ought to be able to raise 14,000 pounds of water one degree, or 140 pounds of water a hundred degrees, or 70 pounds of water two hundred degrees. I do not mean to say that efficiency like this will be attained in the actual circumstances of the combustion of coal in the fireplace. A pound of coal does, no doubt, contain sufficient heat to boil seven gallons of water; but it cannot be made to effect this, because the fireplace wastes in the most extravagant105 manner the heat which the coal produces, so that no more than a small fraction of that heat is generally rendered available. But in the cosmical operations with which we shall be concerned we consider the full efficiency of the heat; and so we take for the pound of coal its full theoretical equivalent, namely, 14,000 thermal106 units. Let us now find the quantity of energy expressed in foot-pounds[2] to which this will correspond. It is obtained by multiplying 14,000 units of heat by 772, and we get as the result 10,808,000. That is to say, a pound of good coal, in virtue of the fact that it is combustible and will give out heat, contains a quantity of energy which is represented by ten or eleven million foot-pounds.
2. A foot-pound is the amount of energy required to raise a pound weight through a height of one foot.
We now approach the question in another way. Let us think of a piece of coal in rapid motion; if the coal weighed a pound, and if it were moving at 224 feet a second, then the energy it contains in consequence of that velocity would, as we have seen, correspond to one thermal unit. We have, however, to suppose that the piece of coal is moving with a speed much higher than that just stated; and here we should note that 92the energy which a moving body possesses, in virtue of its velocity, increases very rapidly when the speed of that body increases. If the velocity of a moving body be doubled, the energy that it possesses increases fourfold. If the velocity of the body be increased tenfold, then the energy that it possesses will be increased a hundredfold. More generally, we may say that the energy of a moving body is proportional to the square of the velocity with which the body is animated107. Let us, then, suppose that the piece of coal, weighing one pound, is moving with a speed as swift as a shot from the finest piece of artillery108, that is to say, with a speed of 2,240 feet a second; and as this figure is ten times 224, it shows us that the moving body will then possess, in virtue of its velocity, the equivalent of one hundred units of heat.
But we have to suppose a motion a good deal more rapid than that obtained by any artillery; we shall consider a speed rather more than ten times as fast. It is easy to calculate that if the piece of coal which weighs a pound is moving at the speed of five miles a second, the energy that it would possess in consequence of that motion would approximate to 14,000 thermal units. In other words, we come to the conclusion that any body moving with a velocity of five miles a second will possess, in virtue of that velocity, a quantity of energy just equal to the energy which an equally heavy piece of good coal could produce if burnt in oxygen, and if every portion of the heat were utilised.
It is quite true that the speed of five miles a second here supposed represents a velocity much in excess of any velocity with which we are acquainted 93in the course of ordinary experience. It is more than ten times as fast as the speed of a rifle bullet. But a velocity of five miles a second is not at all large when we consider the velocities109 of celestial bodies. We want this fact relating to the energy in a piece of coal to be remembered. We shall find it very instructive as our subject develops, and therefore we give some illustrations with reference to it.
The speed of the earth as it moves round the sun is more than eighteen miles a second—that is to say, it is three and a half times the critical speed of five miles. In virtue of this speed the earth has a corresponding quantity of energy. To find the equivalent of that energy it must, as already explained, be remembered that the energy of a moving body is proportional to the square of its velocity; it follows that the energy of the earth, due to its motion round the sun, must be almost twelve times as great as the energy of the earth would be if it moved at the rate of only five miles a second. But, we have already seen that a body with the velocity of five miles a second would, in virtue of that motion, be endowed with a quantity of energy equal to that which would be given out by the perfect combustion of an equal weight of coal. It follows, therefore, that this earth of ours, solely in consequence of the fact that it is moving in its orbit round the sun, is endowed with a quantity of energy twelve times as great as all the energy that would be given out in the combustion of a mass of coal equal to the earth in weight. This may seem an astonishing statement; but its truth is undoubted. If it should happen that the earth came into collision with another body by which its velocity was stopped, 94the principle of the conservation of energy tells us that this energy, which the earth has in consequence of its motion, must forthwith be transformed, and the form which it will assume is that of heat. Such a collision would generate as much heat as could be produced by the combustion of twelve globes of solid coal, each as heavy as the earth. We may indeed remark that the coal-seams in our earth’s crust contain, in virtue of the fact that they partake of the earth’s orbital motion, twelve times as much energy as will ever be produced by their combustion.
It can hardly be doubted that such collisions as we have here imagined do occasionally happen in some parts of space. Those remarkable new stars which from time to time break out derive110, in all probability, their temporary lustre111 from collisions between bodies which were previously112 non-luminous. But we need not go so far as inter-stellar space for a striking illustration of the transformation of energy into heat. In the pleasing phenomena of shooting stars our own atmosphere provides us with beautiful illustrations of the same principle. The shooting star so happily caught on Professor Barnard’s plate (Fig. 16) may be cited as an example.
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warehouse
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| n.仓库；vt.存入仓库 | |
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combustion
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| n.燃烧；氧化；骚动 | |
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ascertain
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| vt.发现，确定，查明，弄清 | |
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ascertaining
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| v.弄清，确定，查明( ascertain的现在分词 ) | |
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celestial
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| adj.天体的；天上的 | |
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luminary
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prim
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| adj.拘泥形式的，一本正经的；n.循规蹈矩，整洁；adv.循规蹈矩地，整洁地 | |
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transformation
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| n.变化；改造；转变 | |
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radical
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| n.激进份子，原子团，根号；adj.根本的，激进的，彻底的 | |
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vestiges
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nebula
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| n.星云，喷雾剂 | |
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illustrate
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| v.举例说明，阐明；图解，加插图 | |
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attained
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| （通常经过努力）实现( attain的过去式和过去分词 )； 达到； 获得； 达到（某年龄、水平、状况） | |
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brilliance
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intensity
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orb
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mighty
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| adj.强有力的；巨大的 | |
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revolves
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| v.（使）旋转( revolve的第三人称单数 )；细想 | |
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majestic
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forth
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torrents
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scattered
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boundless
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prodigality
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dwellers
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solely
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lavished
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lavish
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| adj.无节制的；浪费的；vt.慷慨地给予，挥霍 | |
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illuminate
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| vt.照亮，照明；用灯光装饰；说明，阐释 | |
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immediate
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| adj.立即的；直接的，最接近的；紧靠的 | |
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outrageously
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| 凶残地； 肆无忌惮地； 令人不能容忍地； 不寻常地 | |
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wasteful
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| adj.（造成）浪费的，挥霍的 | |
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prudence
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| n.谨慎，精明，节俭 | |
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apparently
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| adv.显然地；表面上，似乎 | |
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solitary
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| adj.孤独的，独立的，荒凉的；n.隐士 | |
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utterly
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| adv.完全地，绝对地 | |
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38
squandered
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| v.（指钱，财产等）浪费，乱花( squander的过去式和过去分词 ) | |
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exhaustion
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| n.耗尽枯竭，疲惫，筋疲力尽，竭尽，详尽无遗的论述 | |
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hearth
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| n.壁炉炉床，壁炉地面 | |
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41
devouring
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| 吞没( devour的现在分词 )； 耗尽； 津津有味地看； 狼吞虎咽地吃光 | |
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42
incessantly
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| ad.不停地 | |
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43
exhausted
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| adj.极其疲惫的，精疲力尽的 | |
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44
underlie
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| v.位于...之下，成为...的基础 | |
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combustible
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| a. 易燃的,可燃的; n. 易燃物,可燃物 | |
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isle
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| n.小岛，岛 | |
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hurled
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| v.猛投，用力掷( hurl的过去式和过去分词 )；大声叫骂 | |
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expenditure
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| n.(时间、劳力、金钱等)支出；使用，消耗 | |
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conflagration
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| n.建筑物或森林大火 | |
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lavishes
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| v.过分给予，滥施( lavish的第三人称单数 ) | |
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expended
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| v.花费( expend的过去式和过去分词 )；使用（钱等）做某事；用光；耗尽 | |
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generosity
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| n.大度，慷慨，慷慨的行为 | |
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frightful
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| adj.可怕的；讨厌的 | |
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bankruptcy
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| n.破产；无偿付能力 | |
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averted
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| 防止，避免( avert的过去式和过去分词 )； 转移 | |
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squandering
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| v.（指钱，财产等）浪费，乱花( squander的现在分词 ) | |
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genially
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| adv.亲切地，和蔼地；快活地 | |
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temperate
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| adj.温和的，温带的，自我克制的，不过分的 | |
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exuberant
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| adj.充满活力的；（植物）繁茂的 | |
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investigators
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| n.调查者，审查者( investigator的名词复数 ) | |
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interpretation
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| n.解释，说明，描述；艺术处理 | |
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Fahrenheit
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| n./adj.华氏温度；华氏温度计(的) | |
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situated
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| adj.坐落在...的，处于某种境地的 | |
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atmospheric
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| adj.大气的，空气的；大气层的；大气所引起的 | |
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fig
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| n.无花果(树) | |
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observatory
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| n.天文台，气象台，瞭望台，观测台 | |
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astronomical
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| adj.天文学的，（数字）极大的 | |
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discrepancies
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| n.差异，不符合（之处），不一致（之处）( discrepancy的名词复数 ) | |
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investigation
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| n.调查，调查研究 | |
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radius
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| n.半径，半径范围；有效航程，范围，界限 | |
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emission
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| n.发出物，散发物；发出，散发 | |
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enquires
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| 打听( enquire的第三人称单数 )； 询问； 问问题； 查问 | |
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dispensed
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| v.分配( dispense的过去式和过去分词 )；施与；配（药） | |
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perennially
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| adv.经常出现地；长期地；持久地；永久地 | |
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drawn
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| v.拖，拉，拔出；adj.憔悴的，紧张的 | |
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insignificant
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| adj.无关紧要的，可忽略的，无意义的 | |
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deliberately
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| adv.审慎地；蓄意地；故意地 | |
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prospect
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| n.前景，前途；景色，视野 | |
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diminution
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| n.减少；变小 | |
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steadily
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| adv.稳定地；不变地；持续地 | |
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myriads
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| n.无数，极大数量( myriad的名词复数 ) | |
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appreciable
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| adj.明显的，可见的，可估量的，可觉察的 | |
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83
alteration
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| n.变更，改变；蚀变 | |
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deterioration
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| n.退化；恶化；变坏 | |
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spectrum
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| n.谱，光谱，频谱；范围，幅度，系列 | |
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remains
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| n.剩余物，残留物；遗体，遗迹 | |
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prodigious
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| adj.惊人的，奇妙的；异常的；巨大的；庞大的 | |
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liberated
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| a.无拘束的，放纵的 | |
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illustrated
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| adj. 有插图的，列举的 动词illustrate的过去式和过去分词 | |
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ascertained
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| v.弄清，确定，查明( ascertain的过去式和过去分词 ) | |
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remarkable
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| adj.显著的，异常的，非凡的，值得注意的 | |
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luminous
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| adj.发光的，发亮的；光明的；明白易懂的；有启发的 | |
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extinction
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| n.熄灭，消亡，消灭，灭绝，绝种 | |
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dispenses
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| v.分配，分与；分配( dispense的第三人称单数 )；施与；配（药） | |
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dealing
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| n.经商方法，待人态度 | |
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sufficiently
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| adv.足够地，充分地 | |
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97
apparatus
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| n.装置，器械；器具，设备 | |
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phenomena
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| n.现象 | |
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99
precisely
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| adv.恰好，正好，精确地，细致地 | |
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100
entirely
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| ad.全部地，完整地；完全地，彻底地 | |
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101
velocity
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| n.速度，速率 | |
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102
virtue
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| n.德行，美德；贞操；优点；功效，效力 | |
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103
upwards
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| adv.向上，在更高处...以上 | |
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104
ascend
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| vi.渐渐上升，升高；vt.攀登，登上 | |
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105
extravagant
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| adj.奢侈的；过分的；(言行等)放肆的 | |
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106
thermal
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| adj.热的，由热造成的；保暖的 | |
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107
animated
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| adj.生气勃勃的，活跃的，愉快的 | |
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108
artillery
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| n.(军)火炮，大炮；炮兵(部队) | |
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109
velocities
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| n.速度( velocity的名词复数 )；高速，快速 | |
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110
derive
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| v.取得；导出；引申；来自；源自；出自 | |
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lustre
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| n.光亮，光泽；荣誉 | |
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112
previously
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| adv.以前，先前（地） | |
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