Chapter 24 Section 11

three six (14) The example of road signs—this is the meaning of using road signs to place on divergent roads to indicate the direction. ① This is also called a decisive and adjudicative case; in some cases it is also called an oracle and a decree case.Now let me illustrate it.When investigating a certain quality, since there are often and usually two or more other properties co-occurring at the same time, it is difficult for the understanding to distinguish the severity, and it is impossible to determine which of them should be referred to as the cause of the property under investigation. ; then the signpost example can show that one of these properties is firmly and inseparably connected with the nature under study, while the other is variable and divisible; After judging, the former nature is identified as the cause, and the latter is discarded and excluded.This kind of instance gives people a lot of light, and also has a high degree of authority, and the journey of explaining nature sometimes ends and completes with it.

Cases of this signpost may occasionally be encountered among those already mentioned;2 but for the most part it is new, to be sought and applied specially and systematically, and only with careful consideration. It can only be discovered through active and hard work. ① This is the most famous of the twenty-seven priority cases cited by Bacon, and it is naturally the most valuable for investigation. "Signpost case" has become a household term in English, more widely used than any other noun in inductive logic. "It is the simplest and surest means of eliminating irrelevant causes, of choosing among several competing hypotheses" (see Tractatus Natural Philosophy by Herschel) Section 196). "In the process of investigation, there are often two or more reasons, which can explain some phenomena as far as the present knowledge is concerned. At this time, the understanding is in a state of balance, and it is at a loss. If you can find one Facts can only be explained by one of these causes and not by the other, then the indeterminate is settled, and the real cause is ascertained" (see Chapter 3 of "Preliminary Dissertation" by Playfair).The most common example is in chemical processes such as when we perform an experiment to determine the properties of a certain plastid or to detect the presence of a certain toxicity.In terms of logical classification, all instances of signposts can be said to be applications of the law of difference.All other things being equal, the presence or absence or existence of a certain case or a certain group of cases enables us to decide the question at hand.

Playfair once cited as an example the so-called "phlogiston" or "absolute lightness" that metals escape from once they are calcined. It is seen that the metal, when calcined, is heavier than before the application of heat.To explain this fact, there are two theories: one is the phlogiston theory, saying that "absolute light" escaped from it; the other theory is that some new compound was introduced. Lavoisier finally broke the phlogiston theory by using a road sign example.Take a certain amount of tin, store it tightly in a glass crooked neck retort, and weigh it together.Then add fire to calcine, weigh it again, and know that the weight has not changed.After cooling, the still was opened and air flooded in, indicating a partial vacuum.At this time, the third weighing is carried out, and it is seen that there is an extra weight of ten inches, that is, ten inches of air have rushed in.Then the burnt tin was taken out, and weighed ten inches heavier than it was before the fire.From this it can be seen that the weight of the ten inches is absorbed from the air.From this experiment, he discovered the nature of oxygen and its ability to combine with fire metals.

His discovery of air pressure, like Torricelli, is also a good example, see Herschel's "Tractatus Natural Philosophy" Section 246. The above is a comprehensive translation of the annotations of Kachin and Fleur. - translator ② Fleur noted that, for example, it has been encountered in unique cases and famous cases. - translator for example.Assume that the nature to be studied is the tide and ebb tide of sea water.Each of them takes six hours twice a day, and varies slightly with the movement of the moon.Let's look at the divergence encountered here. There must be no more than two reasons for this movement: either it is due to the advance and retreat of the water, as in a basin of water when it is shaken, it overflows to one side and then leaves the other; ups and downs like that. ②The question is: Which of the two should be determined as the cause of the coming and going of the tide?First of all, if it is assumed that the former is the reason, then it must be that when one side of the sea has an incoming tide, the other side must have an ebb tide at the same time.So let's explore that.Careful investigations by Acosta and others have shown that on the coast of Florida and opposite the coasts of Spain and Africa, the incoming tides and the ebbing tides occur simultaneously, not when the former comes. Just the ebb tide. ③However, if we take a closer look, this plot is not conducive to the assumption of the rising movement but enough to defeat the assumption of the forward movement.This is because water can both advance and rise simultaneously on the opposite sides of the same opening, just like when all waters flow in from other places.This is the case with a river: it rises and falls simultaneously on both banks, and there is obviously a forward movement, that is, the movement of the water from the sea into the mouth of the river.Similarly, the above example may also be due to the fact that a very large amount of water from the confluence of the eastern Indian Ocean poured into the mouth of the Atlantic Ocean, so that the incoming tide occurred on both sides at the same time.So again we have to inquire whether there is a tail that would allow the waters of the Atlantic Ocean to recede at that same time to ebb in it, and here we have just the South China Sea, at least as wide as the Atlantic Ocean, and indeed wider and larger enough. for this purpose. ① Fleur noted that this is the view presided over by Galileo.He attributed the alternation of incoming and outgoing tides to the combination of the earth's annual and diurnal rotations.See chapter four of "Dialogidei Massimi Sistemi", Thomas Salusbury English translation, pages 389-390.A few pages earlier (page 383 of the English translation) he also alludes to and ridicules the moon's influence on the tide. - translator

②Fuller pointed out that from the perspective of the following text, if Bacon adopts the later theory, it is obvious that he uses magnetic force to absorb water to explain. But as Einstein stated, "There is also a theory, that of Telesius and Patricius, which compares the ocean to a cauldron of water, which rises and tends to boil under the influence of natural heat from the sun, moon, stars, etc. , and then fell into a deep breath after a while." See Alice and Spadeen's English translation of Bacon's Complete Works, Volume III, p.41. ③ Acosta once mentioned that there are two tides on opposite sides of South America at the same time, which is reflected in the encounter of two tides in the Strait of Magellan; but there is no such sentence mentioned here.

Then we finally come to the instance of a signpost on this episode.It goes like this.If we know for certain that when the tides in the Atlantic occur on the Florida side and on the Spanish side, they also occur on the South China Sea on the Peruvian side and on the Chinese side, then, on the authority of this definitive example, we must Rejecting that assumption, we must say that the incoming and outgoing tides at sea in question are by no means produced by advancing motions, since in fact there is no sea left to accommodate the ebbing tides, i.e. to allow the ebbing tides to take place there simultaneously.In order to ascertain this, it is only necessary to ask the inhabitants of Panama and Lima (the place where the Atlantic and Pacific oceans are divided by a small soil waist) where the tide rises and ebbs at the sea. Both sides of the tide occur at the same time or when the low tide occurs on one side and the incoming tide occurs on the other side.This judgment or this denial seems to be certain, but it must be pointed out that this assumes that the earth does not move. ②If the earth is rotating, then or it may be due to the unbalanced rotation (in terms of speed) of the earth and the sea water, the sea water will be squeezed into a pile and rise up, that is the incoming tide, and then (when there is no pile to pile up) ) relaxes and falls again, that is low tide. ③ But this point needs to be further explored.Even on this supposition, however, we stand firm, that is, when some parts have an ebb and some parts have an ebb at the same time. ① Kachin pointed out that what Bacon called Peru seemed to include the main part of the east coast of South America.See Volume 2, Article 27.

The South China Sea does not only refer to the so-called Southern Ocean, but refers to the Arctic Ocean together with the Pacific Ocean. - translator ② Regarding the question of whether the earth rotates or the celestial bodies rotate, Bacon has a detailed discussion in another example given in the next section of this article. - translator ③ Fleur pointed out, see Galileo's theory on earth rotation and tide, see previous note. Kachin pointed out that the earth's rotation causes giant currents in the ocean, such as polar currents and gulf currents, and also causes trade winds in the air; but it does not cause tides. - translator

Secondly, after we have denied the above-mentioned two causes through careful examination, the former movement is the forward movement, and we must look at the so-called signpost case by taking the latter movement, that is, the lifting movement, as a property to be studied.With regard to this nature, three divergences lie before us.The movement back and forth without the addition of external water can of course be due to one of the following three ways: either water emerges from the earth's interior to join it and then retreats into the earth; There is no increase in the total amount, but only the raw water (without increase in quantity) is stretched or thinned to occupy a larger area and thickness, and then shrinks itself back; Big, but raw water (quantity and density as usual) is attracted by some kind of magnetic force from above, ② rises by induction, and then falls back.We may now put aside the first two causes, and devote ourselves to the last, namely, whether there is such an ascent by induction or magnetic attraction.And see, first of all, it is obvious that since the water is in the center of the trough, the sea, it cannot rise all at once, because there is nothing underneath to fill its void.That is to say, even if water has this desire to arise, it is hindered, stifled, by the cohesive or (as it is commonly called) abhorrent nature of things. ③Then there remains only the case that the water must rise only in part, and therefore subside in the other part.On the other hand, since the magnetic force cannot act on the whole body, it must act on the center with the greatest strength, so that the sea water will be sucked up from the center, and the rest must be reduced from the periphery accordingly. . ① Fleur noted that this is probably the opinion of Telesius and Patricius, see the previous note. Campanella also holds this view. - translator

② Fleur pointed out that from the four or five articles in Volume II on attraction, it is obvious that Bacon adopted the theory of magnetic attraction on the phenomenon of high tide and low tide.This idea may be taken from Gilberte, see the end of chapter 16 of the second volume of "De Magnete". - translator ③ Fleur pointed out that we have seen whether Bacon denied the possibility of the void, see the beginning of the eighth article of the second volume; and refer to the second movement in the forty-eight article of the second volume and the conclusion in the same article.As Ellis said in the preface of the book "Historia Densiet Rori", Bacon's views on this issue have undergone a decisive change after writing the two books "Cogitatione de Rerum Natura" and "Fable of Cupid". of. - translator

Thus we come at last to a signpost instance on the subject.If we see that the water surface is arched and rounded during low tide, the water rises in the center of the sea and sinks from the periphery, that is, the coast, while the same water surface is relatively uniform during incoming tide, and the water is returning to its original state. ,1—If we see this, then, on the authority of this decisive instance, we must affirm that the ascent is caused by magnetism; a statement.It is not difficult to ascertain this, but it is only necessary to test it in the channel with a sounding line, and see whether the center of the sea is higher or deeper in the ebb tide than in the incoming tide.But if this is the case, then we must also remark (contrary to common opinion) that the water must rise in ebb tide and fall in ebb tide to wash the banks. ① Fleur notes that this is the case, although we know this by deduction from the theory of tides rather than induction from observational facts.Camber is greatest at high tide and least camber at low tide. - translator

② Fleur pointed out that despite the test, the tide will eventually turn, so this test will not be conclusive. - translator Take another example.Assuming that the nature in question is a spontaneous revolving motion,1 especially it is to inquire whether the heliotropy which makes the sun and the stars rise and set day by day before our eyes is really a revolving motion in the celestial bodies, or whether it appears to be in the celestial bodies but is really in the earth. exercise.Here, the various situations described below can be counted as an example of a signpost.If we see some movement from east to west in the sea, but very weak and slow; if we see the same movement in the air, but a little faster, especially in the tropic because of the larger circle of rotation ②If we also see this motion in some lower comets, and the motion is already active and powerful here; The distribution is different in order, the closer to the earth, the slower the movement, the farther the earth, the faster the movement, and the fastest in the star world; ③——If we see the above series of situations, then we really should admit that the solar revolution is a real movement in the celestial bodies, and refuse to admit that it is the movement of the earth.For since this revolving motion from east to west is fastest in the highest part of the heavens, and slows down from layer to layer, until at last the earth comes to a standstill and remains still, it is obviously a purely cosmic motion, caused by Caused by the induction of the universe. ④① Regarding the so-called spontaneous rotational movement, it has been mentioned at the end of Article 5 of Volume 2, and it is discussed in more detail in Article 48 of Volume 2 (the 17th type of movement).Fleur points out that these passages show that Bacon is far from having any real conception of the nature of motion.Kachin also said that although we defended Bacon (see the relevant note under Article 5 of Volume 2), on the one hand, Copernicus was juxtaposed with the old astronomers; on the other hand, Galileo was ignored; He is to a certain extent reprehensible for his seeming ignorance. - translator ②Fleur notes that Teresias insisted on this movement of the air, partly on authority, partly on the sound produced by putting hands or horns on the ears (see De Rerum Natura, vol. third chapter). Bacon returns to the motions of air and water in Book II, 48, Article 17, where there seems to be no doubt about the matter. - translator ③ Kachin pointed out that Bacon deeply liked the theory that all circles share a center, that is, the earth is the center point, surrounded by layers of circles, and the outermost circle is the so-called star world.He also divided comets into high and low, which is also related to this theory. - translator ④This passage of Bacon can be regarded as an excellent example of the impossibility of reducing philosophical reasoning to a consistent method of elimination.How is it possible to say that the analogical arguments in the book are compatible with what Bacon seems to have always thought to be the only true way of induction, that of induction by elimination?The argument here rests on a completely illogical factor, namely, on the conviction of the unity, harmony and sex of nature. (Fuller pointed out that assuming that the celestial bodies are revolving around the earth in a consistent motion, of course, the farther away from the earth, the faster the movement. But if we also assume that the earth rotates on its axis, we will get the same completeness as the previous assumption. the same set of phenomena, and if we don't know the fact that the earth rotates, we can imagine that the far point moves much faster than the near point. It seems that even if the conditions of this so-called road sign case are satisfied , would be equally suitable for both hypotheses. However, if the inherent motion of planets and comets is taken into account, the conditions are obviously complicated.——Translator ) as another example.Suppose that the nature to be investigated is another rotational motion of which philosophers have talked so much, that is, the opposite of the sun's rotation, that is to say, from west to east. ①The old philosophers have said that the planets have this motion, and also in the world of stars, ②Caupernicus and his followers also say that the earth has this motion. ③ Now we want to explore whether there is such a motion in nature, whether this is a statement invented and imagined by people for the simplification and convenience of calculation and to satisfy the wonderful concept of explaining the motion of celestial bodies with a complete circle. Our conception of this motion is derived from two phenomena: the inability of a planet to return to its original place in the stellar world during its solar revolution, and the fact that the poles of the ecliptic differ from the world of the poles.But neither of these two points can prove that there is such a movement in the heavens.For the first phenomenon can be well explained by assuming that the stars pass the planets and leave them behind; and the second can be well explained by assuming a spiral motion .Therefore, the above-mentioned two phenomena of planets not being able to go back to their original origin and moving towards the tropics are rather some variations of a solar rotation, rather than a movement that is opposite to the solar rotation or revolves around different poles.Anyone who, for a moment, acts like a human being (discarding some of the illusions of astronomers and scholastics, whose practice has always been an unreasonable depreciation of the senses in favor of the ambiguous), will most certainly assume that this movement is It is actually presented to the senses as I describe it; I once made a machine out of wire to represent it. ①Fuller notes that if readers want to know which astronomical theories Bacon is inclined to, they can refer to "DescyiiptioGlobiIntellectualis" (and a preface to this book by Ellis), "Thema Coeli", "DeAugmentis Scientiarum" (Volume III Chapter IV), "De Fluxuet Refluxu Maris" and "De Principiisatque Originibus".At the end of "Thema Coeli", Bacon expressly denies the motion from west to east, and ascribes the phenomena of planetary motion to differences in speed. ② Fleur pointed out that this may refer to those theoretical systems that distinguish the "stellar world" from the "primary mover", such as Gassendi (1592-1655, French mathematician and philosopher home, has contributed to astronomy) that is to say.See the relevant notes under Article 60 of Volume 1. - translator ③Fuller pointed out that there were those who believed that the heavens turned from east to west in the old theory, and Copernicus replaced it with the assumption that the earth itself turned from west to east. - translator ④ This passage has failed to improve the credibility of the author.Bacon does not seem to have seen that, in order that phenomena may be grouped under any general law, one of the chief necessary steps is to first decompose the motion which is presented to the senses into other, simpler motions.The transition from motion before the senses to real motion cannot be achieved without a decomposition of the former, as Bacon here condemns.As for the conclusion here that "this movement is actually presented to the senses", no astronomer would disagree.There is no doubt about this; but the whole passage shows how little Bacon understood the extent and value of astronomy in his own day. Fleur also comments: Dr. Whewell (Dr. Whewell) said, "Bacon's assertion that the motion of each planet is a spiral to the senses, we may say that this is undoubtedly true; but the task of science, here and It is the same everywhere else, but it is breaking down complex phenomena into simple ones, and complex helical motions into simple circular motions" (see "History of the Inductive Sciences", third edition, p. vol. 1, pp. 388-390).Bacon, here and elsewhere, whenever he deals with astronomical problems (for example, in "De Augmentis Scientiarum", Book III, Chapter 4), always plays down the importance of the application of mathematical calculations to the motions of celestial bodies.But where would modern astronomy be without the help of mathematics?As a result of careful mathematical investigation, Adams (1819-1892, British astronomer) and Le Verrier (1817-1877) , French astronomer-translator ) and the discovery of Neptune at the same time, this fact alone (not to mention the more familiar events such as the prediction of solar and lunar eclipses) is enough to refute Bacon's view. The following example is an example of a signpost on this subject.If we see in a trustworthy natural history that there was a comet, either high or low,11 Fleur notes that Bacon, in De Fluxuet Refluxu Maris, speaks of the lower comet, saying that it is an orbital disk below the Moon.Many philosophers in ancient times believed that all comets are below the moon.In fact, all real comets belong to the solar system and not to the earth system.However, when we read ancient writings we must remember that by comets they often mean only meteors in the atmosphere. - translator If its direction of rotation does not coincide (however irregularly) with the solar revolution, but in the opposite direction,1 then we can of course establish this to the extent that there may be such exercise. But if no such thing can be seen, then it must be considered a problem, and recourse to other signpost instances of it. ① Fleur notes that the planets and their satellites, with the only known exception of the satellites of Uranus, move in so-called prograde motion, that is, from west to east, and that comets appear to be almost equally divided into two types: one There is a direct movement from west to east, and a retrograde movement, from east to west.But what Bacon needs here is a comet whose inherent west-to-east motion more than compensates for the sensual, east-to-west diurnal motion of the heavens, so that it can be seen as opposed to the heavens. Row.Had this been discovered, it would seem that he would have believed in a west-to-east rotational motion, which (which Bacon believed to have been invented by astronomers merely for the sake of calculation) was not merely a diurnal motion. a variant of . If such a case cannot be found, then, he said, we must continue to doubt the theory until another case of signposting can be found to settle the question. - translator Again, take weight or heaviness as the property to be studied. ①There are two divergent roads here, that's it.Heavy bodies must tend toward the center of the earth for no other than two reasons: either because they themselves have this property by virtue of their inherent structure; Move towards it through sympathy.If the latter of the two is the real reason, then it must be that the closer the heavy body is to the earth, the more rapid and violent its motion toward the earth is, and the farther it is from the earth, the weaker and slower its motion toward the earth is (like magnetic force like the plot of attraction); and this activity must be limited to a certain extent, that is, if they are moved to a point so far from the earth that the nature of the earth can no longer act on them, they will be like the earth itself. The same hangs there and never lands.In this regard, the following example may be regarded as an example of a signpost.Take a clock that moves by plumb weights, and another clock that moves by compressed iron springs, align the two clocks so that they both run at exactly the same speed; then place the former on a high On the top of the steeple of a very high chapel, put the latter still below; thus carefully observe whether the clock on the top of the pavilion runs slower than the former because of the reduced virtue of the weight of the hammer. .The experiment was also to be repeated in a very deep mine; that is to see if the clock went further than before because of the increased virtue of the weight of the hammer after it had been placed there. be quick.If we see that the weight of the hammer decreases on the roof and increases in the cave,3 then we can conclude that the suction of the earth's mass is the cause of the weight. ①Regarding this passage, Ellis commented in the note of the English translation: Voltaire once said that "Bacon's greatest contribution in philosophy lies in his judgment on attraction", and he quoted this passage in the certificate to support it. thesis. But in fact, the concept of suction in one form or another (such as the moon's suction of sea water) has been conceived as early as the childish period of speculating on nature; The clarity of Berth's argument. Fleur said Ellis was unfair in his argument.Even if it is said that Bacon got this idea from Gilberte, at least the distinction between the concept of attraction and the concept of magnetism should be attributed to him.Fleur also said that what was said in this stanza fully showed Bacon's sensitivity; this stanza is one of Bacon's few words that make him worthy of being called a scientific pioneer and method reformer. - translator ②The original Latin text is horologium.Fleur noted that this must mean that the pendulum clock had not yet been invented. - translator ③Fuller pointed out that although the experiment suggested by Bacon is creative, it also shows that there is one point that he does not understand, that is: when the height is above the ground, when it is on the ground, and when it is off the ground, the law of suction is different. of.When a homogeneous sphere attracts a molecule outside it, the attraction is inversely proportional to the square of the distance of that molecule from the center of the sphere; is proportional to the distance of that molecule from the center of the sphere.Therefore, the suction reaches its highest level when it is on the ground, and it all decreases when it leaves the ground and goes down into the mine or goes up into the sky.In other words, a clock that moves with the weight of a hammer should go slower and slower no matter the higher it goes up the hill or the deeper it goes into a hole.Therefore, the first part of Bacon's hypothesis is correct (it is enough to be a signpost example in itself), and the latter part is wrong. - translator Take another example.Assume that the polarity of the iron needle when it is touched by a magnet is taken as the property to be investigated.Regarding this property, there are two divergent paths: either the tactile sensation of the magnet itself endows the iron needle with a north-south polarity; Earth's appearance and teleportation.It was this latter which Gilbert conceived and painstakingly tried to prove. ①The observation materials collected by him with great wisdom and great efforts all tend to this point.One of them is: An iron nail, after being placed for a long time between the north and the south, will thus acquire the polarity without the touch of the magnet; ②as if the earth itself is weak because of the distance (he insists that , there is no magnetic force on the surface or shell of the earth), but the magnetic force can still be exerted to excite the iron nail under such a long-term duration, and it can be adjusted after it is excited to make it turn.There is another observation that iron, when it has been heated to white heat and cooled down, is placed vertically between north and south, it also acquires polarity without the touch of a magnet; as if the molecules of iron first After being burned, it starts to move, and then gradually returns to its original shape. When it gradually cools down, it is easier to feel the nature emitted from the ground than at other times, so as to be inspired by it.These things, though well observed, do not quite confirm his assertion. ① Fleur noted, refer to the whole book "De Magnete" by Gilbert, especially the first chapter of the sixth volume.There is no doubt that the latter assumption is correct.The earth can be regarded as a large magnet, and its magnetic heat has a slight distance from the earth pole. The angle formed by the gap is the so-called deflection angle or difference of the magnetic needle. - translator ② Fleur noted that this observation and the next observation can be found in the first and second chapters of the third volume of "De Magnete". - translator On this question, the following episode may serve as an example of a signpost.Take a small globe of magnetite, and mark its two poles; make the poles of the ball point east and west, and not north and south, and let them remain so; It will take six or seven days to put it in place.The iron needle always turns away from the poles of the earth and turns towards the poles of the magnet when it is on the magnet (it is not disputed on this point).Therefore, as long as the magnet ball is always placed as mentioned above, the iron needle will always point to things.The point now to be seen is, if the needle, as soon as it has been removed from the magnet, and placed on a pivot, turns north and south at once, or gradually in that direction, then we must admit the presence of the earth as the cause; If it still points to things, or loses its polarity, then we must consider the cause of this point to be a problem and make further investigations. ②①The original text of the Latin version is terrella.Gilbert used the word to refer to a spherical lodestone.Since he considered the earth to be a large magnet, he called the spherical magnet a small earth.See Chapters 7 and 8 of "DeMagnete". ② Fleur noted that, of course, the previous paragraph must be factual.No matter how magnetized an iron needle is, once it is left free and freed from the influence of other magnets, it always turns itself north-south. - translator Take another example.Suppose the property to be studied is the real plastid of the moon. ①That is to say, we shall inquire, whether the plastid of the moon is thin and composed of fire or air, as most of the old philosophers maintained; or thick and solid, as Gilbert and As many recent people, as well as some ancients, have argued. ②The reason for the latter is that the moon reflects the sun's rays, and it seems that only solid objects can reflect the rays. ③In this matter, therefore, an example of a signpost, if any, must prove that reflection can also take place from a thinner body, such as a flame, provided it is of sufficient concentration. ④We know with certainty that one of the several causes of the twilight scene is the sun's rays reflected from the upper part of the air. ⑤In the same way we have seen from time to time the reflection of evening sunlight from the edge of wet clouds no less radiant than that from the moon, only brighter and more radiant,⑥But here is no evidence that Those wet clouds have coalesced into dense bodies like water.We also see the dark air behind the glass windows at night reflecting the light of candles, as dense objects do. ⑦① Fleur pointed out that Bacon also discussed the matter of general celestial bodies in "Descriptio Globi Intellectualis" (Chapter 7) and "Thema Coeli". ②See the first, third and following chapters of the second volume of "De Mundo Nostro Sublunari" by Gilberte. (Fleur points out that this should be an allusion to Gilbert's well-known opinions, not to his writings, since the above-mentioned posthumous work was not published until 1651. But it is also possible that Bacon Have read its manuscripts.—Translator ) ③ Fleur pointed out that, judging from Gilbert's book, this is indeed not his argument.He is right in arguing that the moon is opaque and solid from the fact that the moon does not transmit any sunlight during a solar eclipse (see Book II, Chapters 1 and 3).Nor did he say that light can only be reflected by solid objects, and during the discussion he referred to the familiar fact that water reflects light. - translator ④ Fleur pointed out that all objects, as long as they are not absolutely black or absolutely transparent, can reflect light, and the degree is of course very different.A flame is nothing but burning gas. - translator ⑤ Fleur noted that there is also refraction, which, like reflection, is the cause of this and similar phenomena. - translator ⑥Comparing the light of the day and the moon with the light of the clouds, this was creatively used by Bury (P. Bouguer, 1698-1758, a French physicist) to determine the ratio of moonlight to sunlight. ⑦ Kachin pointed out that Bacon's explanation of this phenomenon was wrong.It is the glass, not the air, that reflects the candlelight; the glass actually reflects the light all the time, but we can only see it when there is neither light nor anything on the back to spoil the image produced. - translator We may also try the experiment of letting the sun's rays fall on a dull bluish flame through a hole; and we will see that the bright sun's rays, falling on a darker flame, seem to make it lose its light. The light fades so that it appears more like white smoke and less like flame.These are examples of the signposts I have so far encountered on the subject, and perhaps better ones will be found. ① But we must always be careful that the so-called reflection from the flame can only be obtained from the flame with a certain depth, because otherwise it crosses the limit of transparency.But it can always be established that light falling on a uniform body is never absorbed, transmitted, or reflected. ①Kachin pointed out that this kind of projective motion has now become a branch of dynamical science, and all discussions about forceful motion and natural motion have long since come to an end. - translator Take again, as a property to be studied, the motion of projectiles through the air (javelins, arrows, ball throws, etc.).The explanations given by the scholastics with regard to such movements were as a rule extremely careless.他们以为只把它叫作一种强力的运动以别于他们所称的另一种自然的运动就足够了；①他们对于第一次的冲击或第一次的推进只是用这一条原理来解释，就是说由于物质的不可入性所以两个物体不能占据同一地位；至于这运动以后又如何前进，他们就绝对不再操心过关于整个这段话，克钦评论说，培根似乎倾向于认为月的质体是稀薄的而不是坚实的，与吉尔伯忒及新学派的意见或有冲突。后者主张月亮为坚实的质体，而证据却无大价值。但现在说来，这已无甚意义，因为我们现在不仅对于月亮，甚至对于一些距离最远的行星，已能精确地计算出其密度了。 ①弗勒注明，参看一卷六六条下有关的注。 弗勒也说，这些事例证明了非坚实的物体也反射光线，因而接下来便说，我们不能因为月亮反射光线就推断它是坚实的物体。但是，这些事例尽管处分掉了论据，却处分不出结论。非坚实的物体是否反射光线这一问题正是所谓单方测验（unilateraltest）之好例：假如说否，那就证明月亮是坚实的物体；假如说是，那就什么也不证明。到了今天的时代，我们对于月亮已能加以称量，已能知道一些它的化学成分，已能完全准确地画出它的表面，这是培根始料所不及的。 - translator 问了。现在要指出，在这个探究上有下述两条歧路，也就是说，这种运动的原因可以有下述两种解释：或者说这是空气把投射物托送前进，并不断在后聚拢起来加以推拥，就象川之于舟，风之于草那样；或者说这是由于物体自身的分子不能禁受内压，因而不断向前推进以求把自己解脱出来。前一解释是弗拉卡斯多吕亚斯以及几乎所有带有诡思进入研究的人们所采取的。①空气于此也是有一些关系。毫无疑问，但无疑只有后说才是真的解释，这是由无数实验中可以见到的。下述事例就是关于这个问题的若干路标事例之一：一个薄的铁片或一段硬挺的铁丝，或者甚至一个劈作两半的芦管或羽茎笔管，当以拇指和食指把它们弯作弧状时，它们就会跳突而去。显然不能把这个运动归诿于拥聚在物体后边的空气，因为这运动的源头是在铁片或芦管的中部，而并不在它们的两端。②①爱理斯在英译本中注明，说见弗拉卡斯多吕亚斯所着《交感与反感》第四章。 他又提到，在柏拉图的“Timaeus”一篇对话中，已有空气参加产生投掷物的连续运动之说。柏拉图在那里谈到呼吸，其理论是说：口鼻呼出的空气推挤外边邻近的空气离开其位置，这又扰动了附近的空气，如此递推直到形成一圈，然后空气又因反激作用而被迫通入肌肉，填满胸膛中的空凹——简言之就是说空气通过人体而循环。根据这一原理，他还将进而解释其他多种现象，如拔火罐、吞吸作用、投射物的运动，等等。但对于这些现象，他仅提议作此解释而未加以说明。 到了勃鲁塔克（Plutarch of Athens，第五世纪时哲学家，雅典新柏拉图学派的创始人），又发展此说而对上述现象一一作出解释，见所着“Quaest．Platon”．一书第十卷。 弗勒还指出，亚里斯多德亦认为投射物的运动是靠空气来维持的，见所着“Physica”第四卷第八章和第八卷第十章。弗勒最后说，要来批判这个和这类运动学说，实为对读者的忍耐性作不适当的苛求。总之一句话，古代和中世纪物理学中的这些黑暗之点，自那简单明了的运动的第一条法则出现之后，已经一下子都被照亮了。 - translator ②弗勒指出，尽管上文已把问题划清，这里却似又弄错问题之所在，仍把问题说成在于投射物运动之起源而不在于其继续。再说，即使这个事例算是切题的，它也只是破除一说而无助于另一说。 - translator Take another example.假定所要研究的性质为火药之膨胀为火焰那种急遽而有力的运动，①那种象在地雷和血炮中所见到竟能把很大的块体炸起、竟能把很重的东西射出的运动。关于这个性质，有这样两条歧路：这种运动之激起，或者是仅仅由于物体经点火后所发生的膨胀欲求；或者是一部分由于上述欲求，一部分又由于物体中的粗糙元精有急速从火中飞出的欲求，因而就猛烈地突出火的包围，如似越狱一样。经院学者和普通人们的意见都只说到了前一欲求。他们以为，只要断言火焰为其四大元素性的法式所规定必然要占据大于物体在粉末形式下所填塞的空间因而结果当然发生这种运动，自培根在“Cogitationesde Natura Rerum”一书第八章中，对这问题还作了更详细的讨论，并增添了一些别的实验，但也都不比这里所举的事例较有特定意义。 己就算是很好的哲学家了。他们却忘记注意到，在火焰业经生出的假定之下这话说来固然是对的，但根本上火焰的生出却大有可能被足能压制它和窒息它的大块物质所阻止；所以这事情还并不能就归到他们所坚持的那种必然性。假定火焰业经生出，再来说必然要发生膨胀，并从而必然要把反对的物体射出或卸掉，这些判断当然都是不错的。 但假如有坚实的块体在火焰生出之前就把它压住，那么所说的这个必然性可就完全落空了。而我们看到火焰，特别是当其生出之始，恰是柔弱温和，需要有空当来活跃来锻炼自己的力量的。因此那种暴烈性便不能归之于火焰自身。事实是，那种带风火焰，或者亦可叫作带火的风，乃是起于性质正正相反的两个物体的冲突：一种是高度的易燃性，那是硫磺所具有的性质；一种是恶燃性，象硝石中的粗糙元精就是那样。这两种物体间发生着异乎寻常的冲突：硫磺尽其全力来燃发火焰（柳木炭这第三种物体只不过把其他二者联合和结合起来）；硝石的元精则竭其全力要逃突出去，同时并膨胀起来（空气、水以及一切粗糙物体受到热的影响时都是要膨胀的），而在这样飞逃奔突之中却又象暗装的风箱一样从各方面扇动着硫磺的火焰。①弗勒指出，这个问题在Cogitations De Natura Rerum一书第九章中也有所讨论。 培根以“两个物体的冲突”来解释爆炸，使用了“硝石中的粗糙元精”这类说法，这些都是他自己的也是那一时代的化学观点的特征。我们必须记住，化学那时还未具有科学的形式，并且深为幻想式的和隐喻式的用语所牵累。 至于火药之所以具有强大的爆炸力，其真确的解释是“由于大量气体，主要是氮和碳酐的骤然发展，这些气体所占空间在通常气温下约三百倍于所用药粉之体积，而在爆炸的一刻由于剧烈骤增之故则膨胀到至少为火药体积之五百倍。”见密勒所着《化学原理》（Miller's Elementsof Chemistry）第二部分，三九九至四○○页。 - translator 在这个题目上我们可以有两种的路标事例。①一种是那些具有最高易燃性的物体，如硫磺、樟脑、石油精和其他等等，以及它们的混合体；它们如不受到阻碍，是要比火药还更容易着火和更快地燃烧起来的（从这里就可看出，火药的那种宏大的效果并不是由爆发火焰的欲求自身所产生的）。另一种事例就是那种躲避和憎恶火焰的物体，如一切盐质便是。我们看到，盐粒投入火中后，其水质的元精先要带着迸裂的声响迸出，然后才燃发火焰。这种情节也见于各种比较硬挺的树叶，它们也是先有水质分子逃出然后才见油质分子燃烧，不过程度较轻罢了。而最显明的情形则见于水银，那真无愧于矿物水之称。②它不必燃发火焰，仅凭它的喷发和膨胀就几乎能与火药的力量相颉颃，而据说若与火药混合起来还更增加它的力量。①弗勒指出，这些路标事例固能处分掉相竞的假设，却未能建立起培根自己的假设。 要在这样一种例子中把多种可能的解释都说尽，这需要对这个题目具有远远更多的科学概念，非培根及其同时人物那时所得获致的。 - translator ②水银蒸气在高温下具有极大的膨胀力，这是众所周知的。 最后再举一例。假定所要研究的性质为火焰的过渡性和逐时逐刻的熄灭性。我们知道，火焰在我们这里看来并没有固定的最后一贯性，而是在瞬生瞬灭之中的。很明显，我们所看到的延续存在中的火焰并不是同一个火焰的继续，而是一系列按照规律而生的新的火焰的连续。若以数计，火焰亦不是保持前后等同的。这点很容易看到，因为只要把燃料一撤，火焰立刻就熄下去。关于这种逐时逐刻的熄灭性质，有着两条歧路，是这样的：或者是由于最初产生火焰的原因，象在光与声和所谓“强力”运动方面的原因停止下来；或者是由于火焰按其自己的性质虽然能够保持，但却受到周围许多相反性质的伤害而遭到消灭。 于是在这个问题上我们可以取下述事例为一个路标的事例。我们都看到大火中的火焰升得如何之高；这是因为火焰的底盘愈宽，其顶点就愈高。由此可见，熄灭是从周边开始的，因为火焰在那里受到空气的压束和干扰。至于火焰的中心，因其为周边的火焰所围绕而不遭空气的触动，则是能够保持数字上前后等同的；而且它亦非到逐渐被周围空气压紧的时候不会熄灭下去。这样看来，可以说一切火焰都是金字塔形的，底盘宽，顶点尖；底盘为燃料所在，顶点则有空气为敌而又缺乏燃料。说到烟，那却是底盘狭窄而愈上愈宽，恰似一个倒转的金字塔形。①这理由就在，空气能容纳烟而要压束火焰。 请人们不要梦想点着的火焰就是空气，事实上它们乃是性质大异的质体。②①弗勒注明，火焰之所以形成金字塔形，是因为其成分之一（氧气）固系平匀地散布着，其他一个则有其固定的源头。后者（这在纯粹的情况下构成所谓未燃的核心）距离其源头愈近，其圈盘就愈大；因为它退离其源头愈远，被消耗的就愈多。烟则不同，它不与任何其他物体进行化合或冲突，所以能够自由散布，因而就取得书中所写的形式。 这样说来，培根之将火焰的形式归因于其对周围空气的接触，这在某种意义上是对的。 ②“点着的火焰就是空气”疑应作“点着的空气就是火焰”。 克钦指出，培根的结论谓空气压束火焰，又谓点着的空气就是火焰之说为荒谬，这些都是不幸根据不足的武断，实则空气正是火焰的主要支持者。 弗勒注明，火焰之熄灭当然是由于火焰所借以化合而生的这种或那种气体供应遭到切断。空中的气不独无碍于火焰，在绝大多数情节中空气中所含氧气甚且是火焰所借以化合而生的诸种气体之一。同时，氧气一经带入火焰的中心，立刻就消耗其他气体，从而也会因破坏了火焰的成分之一而使火焰熄灭。 - translator 我们还可有一个更合用的路标事例，假如我们能用两种颜色的两种光来把这事表示明白的话。把一支点着的蜡烛插在一个金属的小蜡台上，放在一只碗底当中，周围倒上酒精，但不要漫过蜡台。然后把酒精点着了火。这时酒精发出蓝色的火焰，而蜡烛则发生黄色的火焰。注意观察蜡烛的火焰（这是很容易用颜色来与酒精的火焰分别开的，因为火焰不象液体那样立刻就混合起来）在并没有什么东西来破坏它或压束它的条件下是保持其圆锥形状还是趋向于圆球形状。①假如看到它有后一情况，那么我们就可以确然断定说，火焰只要在其他火焰围护之中而不感到空气的敌性活动，它是能保持数字上前后等同的。①弗勒注明，这一实验在“Sylva Sylvarum”一书中第三一项实验下还有详尽的叙述。爱理斯在那里注道：“这个实验的解释很简单，就是说，在不纯的空气当中，构成火焰的蒸气在遇到足够的氧气来形成完全的燃烧以前经热而散布开来，以致火焰在体量上增大起来。” 我们或许可以推重培根说他曾模糊地看到空气与火焰有某种联系，但这整个的臆测也同前两个一样，却是离题甚远的。 - translator 关于路标的事例，说到这里算是够了。我在这一点上讲得比较详细，目的乃在要使人们逐渐学会并逐渐习惯于使用路标的事例和光的实验来对性质进行判断，而不要使用或然的推论来对性质进行判断。