The Sun. [Footnote 154]
[Footnote 154: This lecture was delivered by M. Secchi to the scholars of the school of Saint Genevieve, on the 28th of July last, at a scientific soirée, presided over by Mgr. Chigi. It occupied two hours in the delivery, during the whole of which time the lecturer held captive the attention of his distinguished audience, who testified their appreciation of its scientific and literary merits by warm applause. The lecture will speak for itself. But in publishing it, there is one thing which cannot be reproduced; that is, the deep interest which necessarily attaches to the hearing a learned man himself explain his experiments and his discoveries. A number of figures were necessary for the illustration of certain parts of the lecture; and these, prepared from M. Secchi's designs by M. Duboscq, optician, were projected on a screen, by the aid of the electric light, thus enabling the spectators to follow the learned astronomer with greater ease. Of these designs, etc., only the most essential have been given in the published lecture.]
Gentlemen: From the beginning of my stay in Paris, I was invited by persons to whom I owe great deference to lecture to you on some of the subjects which are studied at the Observatory of the Roman College. This invitation I felt to be in the nature of a command, which I would readily have obeyed long before, had I not been prevented by numerous and incessant cares. I cannot, however, leave France without discharging the debt; and it is for this purpose that we have met together, on the present occasion. I propose to speak to you of the sun, and to show you what science teaches us of its physical constitution. For eighteen years I have studied the sun, and observed all that passes over its surface. I hope, also, to interest you in acquainting you not only with the fruit of my own labors, but also with the discoveries of my learned contemporaries.
What is the sun? Such is the question which has been frequently asked me. I confess it has always perplexed me to reply to it. I should not be pardoned, perhaps, if I should say I know nothing of the matter; nevertheless, it is impossible for me to give a complete and satisfactory answer. You yourselves have addressed this question to me with an eagerness which I appreciate as a particular honor; and, in responding to your desire, I am going to place before you the very interesting results which we have obtained in the study of this luminary, to which, after God, its creator, we owe all the physical blessings we enjoy here below.
To deal with this vast subject in something like an orderly form, let us speak first of the new means of observation with which modern science has furnished us; after which we shall see what advantage we have derived from them, and in what way they have served to make us better acquainted with the sun.
Astronomers, gentlemen, are not privileged beings. Like simple mortals, they are dazzled by the sun. Far from sharing the penetrating sight which poets accord to the eagle, they cannot fix their gaze on the bright orb of day without exposing their eyes to the greatest danger; and this danger becomes more serious if they employ their instruments for this purpose without taking proper precautions. Until recently, two means have been employed to protect the eyes of the observer: first, the reduction of the objective aperture of the glasses; and second, providing strongly-colored glasses. These two expedients present the most serious inconveniences. The first deprives the observer of the advantages which he would gain from the large apertures, and the confusion of the image is greatly augmented by the diffraction which the small diaphragms cause the light to undergo; while the second will not permit of our distinguishing the different colors which may meet in the sun; and on this account the observer is liable to fall into very grievous errors. The means now in use effectually obviate this double inconvenience, inasmuch as they allow of the use of the entire aperture of the glasses, and leave to the different parts of the sun their natural color. The first means consists of the employment of the reflective glass. A rectangular prism of crystal is disposed in such a manner as that its hypothenuse has an inclination of 45 degrees on the axis of the glass. The light, on reaching the surface, divides itself into two very unequal parts. The reflected rays are rather feeble, but of sufficient brightness to make them pass through a glass faintly colored, falling perpendicularly on one of the faces of the prism, without reaching the eye of the observer. The colored glass, not having to sustain so high a temperature, is not so liable to break, as often happened in the old method.
If the colored glass is completely done away with, we shall succeed by adopting a method which rests on the properties of polarized light. When the light is reflected by a glass mirror under an angle of 35 degrees 25 minutes, it undergoes a modification which is called polarization. If the rays thus polarized are received on a second glass mirror under the same inclination of 35 degrees 25 minutes, they will divide into two parts, one part of which will traverse the glass, and the other will undergo a second reflection. The quantity of light reflected by the second mirror will depend on the relative position of the two surfaces of reflection. It will be at the maximum if these surfaces are parallel, but otherwise if they are perpendicular; so that, by varying the relative position of the two mirrors to each other, we may either augment or diminish gradually the intensity of the reflected rays. Such is the property of the polarized light, which is utilized for making observations of the sun. To the eye-glass of the instrument are fixed two smooth mirrors, so adjusted as to make to the direction which the light follows an angle equal to the angle of polarization. One of these mirrors can turn round to the reflected rays. Then, by putting the surface of the second almost perpendicular to that of the first, we can observe the sun as easily as we can the moon, seeing it in its natural color, and we can regulate at will the intensity of the light. It is to this new arrangement of the eye-glasses that we owe the greater part of the discoveries of which I am about to speak to you. I ought to add, however, that in the astronomical glasses we employ not only two, but three and even four, of these reflections.
But to come to the consideration of the sun. Everybody knows that it has spots; that these spots, relatively very small, are of a black color, and also, that they adhere to the body of the sun. They move in a manner leading us to the conclusion that this luminary turns on its own axis in the space of twenty-five and a quarter days, and that its equator has an inclination of seven degrees and a half on the ecliptic. These spots are far from being constant. They undergo, on the contrary, the greatest changes both of form and size. They show themselves particularly in some zones, and appear and disappear at very irregular periods. The maximum and the minimum are reproduced at intervals of about eleven years. One of the most curious discoveries of our times is, that this periodicity of the solar spots has some correspondence with terrestrial magnetism. It is impossible to discover the point at which the two classes of phenomena unite, but the existence of the fact is incontestable. Thus, we have just seen the spots pass through the minimum. From September, 1866, to March, 1867, there were scarcely any of them; and during the same period the magnetic perturbations have been very feeble. As soon as the existence of these spots had been fully ascertained, the questions naturally arose, What is the cause of them, and what their nature? On these points there have been numerous opinions, all as diverse as possible. This is not to be wondered at; for hitherto there has been no correct observation from which could be learned the character and the particulars of the phenomena we desire to explain. So, without stopping to discuss ancient theories, I am about to bring before you the latest observations, and the conclusions at which we have arrived. The drawings of the first observers represent the spots as formed with a black centre surrounded by a gray tint of a uniform figure, which is called penumbra. It is not surprising that, with such imperfect means of observation, the theory of the spots should remain so long uncertain, and that these phenomena should have been taken for simple clouds floating in the solar atmosphere. This theory, which was put forth by Galileo, has been revived in our day. The solar spots have an aspect completely different from that which we see in the ancient cuts. I am going to show the drawing of several of them as observed at the Roman College. I designed them myself, by a very rapid process, such a process being very important for objects essentially variable, and which change their form with great rapidity, and in a short space of time. Here is, first, one of the most common forms. (Figure 1.)
Figure 1.
It is a round spot, consisting of a black centre, around which is a penumbra all ragged. The first thing you wall observe is, that the figure of the penumbra is far from being uniform. It is composed of filaments, very long and very thin, which converge toward the centre. These have been called wisps of straw, willow-leaves, etc. I prefer to call them currents, being aware, at the same time, that it is impossible to compare them to any known thing. They are more scattered near the outline of the penumbra, and they become condensed near the centre, where the light is stronger and brighter. These luminous threads start from the outline of the spot, traverse the penumbra, and often run into the black space that forms the centre, where we see them floating singly, gradually becoming smaller, and disappearing after a while.
The penumbra is not always composed exclusively of threads like those you see. The centre is often surrounded by a uniform pale color, over which the currents are disseminated. These currents are not always continuous, and their different parts present an appearance which may be compared to elongated grains.
In spite of the increased power of the instruments we employ to observe the sun, the detached parts of the spots often appear to us as microscopic objects. In order to form an exact idea of their real dimensions, we must always remember that, at this distance, four fifths of a second is equal to 140 kilometres, and consequently these apparent threads, whose seeming width is at most not more than one or two seconds, are in reality immense currents, being, about the middle, of 600 or 700 kilometres in width, while their length is at least equal to the diameter of the terrestrial globe.
The drawings which you have just seen represent some of these spots in their complete form and exactly defined. But they present themselves oftener under fantastic and irregular forms. They are sometimes accompanied by a kind of tail, itself formed of black spots, and which seems to follow the centre in its motion. We have here a curious example. The centre is not quite black; we meet with shadows there—some gray, and others red; the filaments on all sides fall toward the centre, and their edges are turned back and bent, as if they had experienced some resistance, or as if they had encountered a whirlwind.
Figure 2.
Here is a spot of this kind, (Figure 2,) the details of which are most instructive, and most important in a theoretical point of view. We find the centre divided in several parts by the luminous threads. This appearance was remarked by the ancient astronomers, who explained it by supposing that on the surface of the sun solid crusts were formed, which broke into shivers like glass under a blow from a stone. Modern observations, however, do not admit of this explanation. They show us clearly that these divisions are produced by currents which, leaving opposite edges, meet in the middle of the centre, and thus divide the spot into several parts.
The formation of a spot is never instantaneous. It is ordinarily announced by the appearance of several black points, and by a kind of diminution in the thickness of the luminous bed. These little cavities multiply themselves; one of them develops itself, absorbing the others, and the process ends in the formation of a black spot in the centre. In this first phase the movements of the spots are very irregular, and their advance is always to the front, by reason of the solar rotation.
The drawing which is now before you represents the first appearance of a great spot which was formed almost suddenly on the 30th of July, 1865. The day preceding that of its appearance, in observing the sun as usual, we had remarked only three little cavities, of which we noted the position. On the 30th of July, at mid-day, we found in the place of these cavities an enormous spot, the surface of which was equal to at least ten times the size of our globe. It was so mobile, and its form changed so constantly, that we could scarcely draw it. We could discover in it four principal centres, where the movement of the matter was visible in the form of a whirlwind. In an interval of 24 hours it had undergone some considerable changes. On the 31st of July, the four centres were completely distinct, and the matter which separated them seemed as if it were stretched out. During the days which followed, this form became more and more marked. Soon there were four spots clearly defined, which ultimately assumed the form of four independent craters or cavities. In the interior of these craters we perceived some light shadows, whose form reminded us of that of the clouds we call cirrus. Their color was different from that of the other part of the sun which presented itself to view. As the polariscopic eye-glass does not change the color of objects, we are enabled to see that these clouds are often of a very decided red; and, as this tint is clear and well marked, it is impossible to confound it with the effects due to the achromatism of the instruments. You see here a great number of spots presenting this appearance, and especially in Figure 2, where the red shadows seem intertwined with the white shadows. I have more than once seen these luminous tongues, so to speak, transform themselves into red veils.
This hasty view is, however, so complete as to convince us that the spots cannot be compared to clouds, their aspect not warranting such a comparison. If any part of them may be compared to clouds, it is more the luminous matter; for we see it precipitate itself in the obscure space, and there dissolve in much the same way as we see the vapor which forms the mist dissolve into thin air. All that we are required to believe is, that these apparently black masses are but rents made in the luminous veil which covers the solar body, and to which we give the name of photosphere. It is this bed which transmits light and heat to us. It is suspended in the solar atmosphere, just as clouds in the terrestrial atmosphere. What appear to us as spots in the sun is simply the effect of the rents which take place in it. We are confirmed in this view by the well-ascertained fact that the spots are depressions in the solar body, and that they have the form of a funnel. This form becomes very perceptible, when the spots are drawn by the rotary movement toward the solar disk. When we examine a spot situated toward the centre of the sun, we find that the shape of the penumbra is more regular. But when the spot moves toward the edge, we see the penumbra diminish on the side of the centre, and increase on the opposite side, in which case it presents the appearance of a cavity in the form of a funnel looked at obliquely.
Figure 3.
This effect is very clearly indicated in the drawing (Figure 3) which you have now before you, and for which we are indebted to M. Tacchini, the astronomer, of Palermo. We have observed this same spot at Rome, and we have made a drawing of it similar to that you now see; but I would rather exhibit that of M. Tacchini, because it cannot be objected that it was made under the influence of a preconceived idea. You see that in this spot the edge of the aperture is raised much in the same way as in the craters of the moon, and around these apertures are elevations, clearer and more luminous, which we call faculas.
The conclusions which I have just presented to you are also those to which M. Faye arrived, in studying the apparent perturbations in the movements of the spots. In short, what settles the question definitively is the study of the spots of exceptional grandeur when they reach the edge of the solar disk. It is then very easy to prove that the centre is lower than that part of the outline from which radiates the facule. Both M. Tacchini and I proved this at Rome, in studying the grand spot of July, 1865, at the moment in which it disappeared behind the disk of the sun.
The spots, then, are apertures, rents made in the photosphere. But how is it that these spaces do not fill up immediately? This is a serious difficulty, and it leads us to study the structure of the photosphere. If the photosphere was solid, all the movements which take place in it would be impossible. It is, then, fluid. But, on the other hand, a fluid would naturally spread itself until all points of the surface were on the same level, and it would require very little time to fill a gap having the dimensions of even the largest of the spots. The celebrated William Herschel saw this difficulty, and he met it by a solution which we still adopt, because it has been confirmed by observations and discoveries; so that what to Herschel was but a conjecture has become to us a demonstrated truth. The photospheric matter is like our clouds, gauze-like and transparent as ours. We often see among the clouds differences of level—disruptions which enable us to perceive the blue of the sky in the space which separates them. The same thing happens in the sun; and this hypothesis, which is so useful in explaining the phenomena I have just set before you, accords perfectly with all the particulars observed.
We have seen, in effect, the luminous matter remain suspended and floating in the midst of the centre, and the photospheric currents melt in obscure parts, just as our clouds dissolve, apparently dispersing themselves in a space completely deprived of vapor, when the temperature is sufficiently elevated. The little white veil in Figure 1 is a cloud about to be dissolved. Without this dissolving force, the matter which radiates from the circumference to the centre would not be long in filling up this gap. As I told you just now, we have been able to seize the fact of this dissolution of the solar atmospheric matter, and to see these cloud-like forms change into red veils occupying a large surface in the centre.
One thing alone remains to be proved—the existence of a transparent atmosphere. We have for a long time presumed its presence and its action to explain a well-established fact, namely, that the edges of the sun impart to us less of heat and light than the centre. This fact, inexplicable by any known laws of radiation, is easily explained by the action of an absorbing atmosphere; for the rays part at the edge before passing through a thicker atmospheric stratum, proving necessarily an absorption more considerable than that which flows to the centre. The existence of a solar atmosphere, which was formerly regarded as probable, has been reduced to certainty by the observation of eclipses, and it has been shown that veritable clouds float in this gauze-like bed.
Everybody has heard of the magnificent aureola which surrounds the moon during the total eclipse of the sun. It is a truly solemn moment when, the last rays having just disappeared, we see the shadow of the moon projected on a sky of leaden hue, with a perfectly black disk surrounded by a magnificent luminous glory, like that which we see represented around the heads of the saints. This aureola, at least the part nearest the disk, is owing to the atmosphere of the sun. This spectacle is magnificent, but it becomes much more instructive when we examine it through a good telescope. We then perceive around the disk of the moon gigantic flames, of a lively red, the height of which is incomparably greater than the diameter of the earth. Some are suspended without any support, and others take a horizontal direction, like the smoke that comes out of our chimneys. These flames were designated protuberances; but we knew not how to explain them. It was even doubted whether they were real; and we were quite disposed to attribute them to an optical illusion. These doubts have disappeared since the observations we made in Spain during the eclipse of 1860. On that occasion we were stationed at Desertio de las Palmas, on the coast of the Mediterranean, while M. De la Rue took up his post at Riva Bellosa, at a short distance from the ocean. We succeeded at both these stations in photographing the sun at the period of the total eclipse, and a comparison of the two photographs has proved that the protuberances have a real existence, that they have a form so fixed as to give identical images at two points distant from each other by several hundreds of kilometres. The perfect resemblance of the two photographs is the more remarkable, from their not having been executed at the same moment. Between the two operations an interval of ten minutes elapsed. These protuberances, considering their distance and their bent forms, can be nothing but clouds suspended in the solar atmosphere, and it is these which form the red veils that we have seen in the centre. The observation of eclipses proves to us conclusively that the sun is really surrounded by a stratum of this red matter, which we ordinarily see only on the most elevated summits.
In the photograph taken at Desertio de las Palmas during the total eclipse, the exterior form of the atmosphere is perfectly visible. We see that it is more extended at the equator than at the polar regions, which is a natural effect arising from the movement of rotation which the sun possesses. We see, in short, that this atmosphere is livelier in its action in the two zones on each side of the equator, in which the spots ordinarily show themselves. The existence of a solar atmosphere being perfectly in accordance with all known principles and with all ascertained facts, there is no longer any room for calling it in question. We describe the sun, then, as surrounded by a dense atmosphere in which floats the photospheric matter. The surface of the photosphere is far from being uniform and regular. It is, on the contrary, wrinkled all over, and again covered with granulations. These granulations, first perceived by Herschel, have been carefully studied in later times.
When our atmosphere is calm and the observation very precise, the whole bottom of the solar disk appears covered with small luminous grains, separated by a very fine and very dark net-work, resembling in appearance partially desiccated milk, examined through a microscope. These points, or white grains, are of different sizes. Where there are openings, we see around each of them some lines of grains in the form of leaves, more or less oval. Their mean dimension is about the third of a second. These grains are only the upper part of the flame which inclines toward the openings, thus proving that there is a very sensible power of attraction in the apertures. We may even say that these granulations resemble the appearance which the clouds known as cumuli present when, from the summit of a mountain, their upper part is examined. The largest spots would be, then, but an exaggeration of this net-work, ordinarily so fine, produced by the force which caused the flame, or rather, the stratum of the cumulus.
But what is it that produces these spots in the sun? Here the difficulty is singularly complicated. To reply satisfactorily to this question, it would be necessary to become acquainted with what passes in the interior of the solar globe. But let us, without hesitation, and without attempting to delude ourselves, confess that our study of the sun is confined to its external stratum, and to the most striking phenomena of which it is the seat; whereas, with regard to the interior mass, it is only by the process of induction that we are enabled to arrive at any knowledge.
Observations which we have just made lead us to the conclusion that the spots are owing to emanations issuing from the solar body, almost similar to the way in which matter is ejected by our volcanoes. This is proved both by the form of the craters, which you have just seen, and by the columns of clouds, analogous to those arising out of volcanoes, or out of chimneys, observed during eclipses. Here, then, is how we explain the constitution of the photosphere and the formation of the spots. The exterior stratum cools itself constantly by radiation, passes into the gauze-like state, or state of vapor, and ends by precipitating itself in the liquid state, or even in the solid, remaining, however, suspended in the solar atmosphere, as clouds do in ours. It is this condensed matter that forms the photosphere, and it is from that principally we receive light and heat. From some cause or other, a movement from below takes place in the gauze-like mass which is situated underneath. By this movement the photospheric stratum, raised at first, spreads itself on all sides, forming a sort of cushion, and ends by separating itself, leaving a wide opening in the form of a crater. While the volcanic emission lasts, the spot remains open, and it disappears only at the moment when the equilibrium is reestablished, by the luminous matter filling up the void which was formed. If this theory is correct, the circumference of the spots ought to form the mountains above the exterior surface. Now, we have just seen that the outline of the spots is always surrounded by faculae, which constitute prominent elevations. Supposing it is true that the interior mass is the seat of violent action, this conclusion has nothing surprising in it, and we are led to it by a certain number of other phenomena equally remarkable. Thus, every time that a spot is produced, we remark that it is visibly projected with a quickness greater than that of the solar rotation. The projecting mass is then animated with a quickness greater than the surface of the photosphere; and, in order to explain this fact, we must admit that the matter of the interior stratum possesses a quickness greater than the superficial part.
This novel conclusion is supported by another fact. We know now that the rotation of the spots has not the same angular quickness under all the parallels. The quickness is sensibly greater in the equatorial zone than in the higher latitudes. This circumstance forces us to the conclusion that the sun is not a solid globe, but that its structure admits of the different strata of which it is formed having a movement of rotation independent of each other as regards velocity. In fact, the only explanation we can give of this difference of quickness is, that the interior mass is fluid, and that it is moved by a rotary process, more rapid than that of the external surface. We cannot, however, undertake the formal demonstration of this point on the present occasion.
This fluidity of the sun is calculated to surprise you; but you will cease to regard it as incredible when I remind you of certain ascertained facts about this luminary. The gravity of its surface is twenty-eight times greater than that of the surface of our globe, from which results an enormous pressure capable of condensing a large number of substances, or, at least, of singularly diminishing their volume. Looking simply at this fact, the mean density of the sun ought to be much greater than that of the earth. It is nothing of the kind, however, but just the contrary; for the specific gravity of the terrestrial globe is four times greater than that of the solar mass. We must admit the existence of a repulsive force capable of overcoming the molecular attraction, and of rarefying the substances which the weight tends to condense. This repulsive force is probably owing to the heat, and, in fact, the temperature of the sun is estimated at not less than five millions of degrees. At this temperature no matter could remain solid, even in spite of the enormous pressure of which we have already spoken. It is, then, impossible for us to admit the existence of a solid mass, and much more that of a cold centre in the interior of the sun.
And here an objection presents itself to which I ought to reply. If the interior mass of the sun is at a temperature so very elevated, how is it that, when the photosphere opens, a black spot is presented to our eyes? In examining this opening, we perceive a substance of which the temperature is extremely elevated, and which ought, consequently, to be very luminous. How is it, then, that, on the contrary, it presents to us the appearance of a very deep black? My reply is, that the black color of the spots is a purely relative matter; that it is owing to the contrast of the brilliant light which comes to us from the photosphere. If we could see those apparently dark parts away from the glittering mass of the sun, they would appear not only luminous, but dazzling with light.
But you will say to me, it still remains true that the interior mass of the sun is less luminous than the photosphere; but since the superficial part constantly cools by radiation, it follows that there ought to be less heat, and, consequently, less brilliancy in the photosphere than in the interior mass. With your permission, I will make a reply to this which might, at the first blush, appear paradoxical, but which is, nevertheless, the expression of truth. It is precisely because it is of so very high a temperature that the interior mass of the sun sends us a less degree of light and heat; it is precisely because it is cooled at the point of condensation, to precipitate itself in the liquid or solid state, that the photospheric matter becomes hotter and more luminous. To make this plain, we have only to recall certain well-known principles of physics. Two bodies equally hot may not emit the same quantity of heat. One of them may cool itself rapidly in heating the bodies which surround it; while the other may let its heat escape only very slowly, and heat but feebly the neighboring bodies. In this case, we say that the first has a more considerable radiating power. Now, philosophers know that gas has a very feeble radiating power, and that it may be consequently at a very high temperature without emitting around it a great quantity of light and heat. You have an illustration now before your eyes. This lamp, fed by lighted gas, gives a very brilliant flame, because the carbon remains there some time in suspension before burning. Let us throw into the flame a little oxygen; immediately the flame pales, becomes bluish, and ceases to be luminous. Its temperature, notwithstanding, has greatly increased, and it is now the celebrated gas by the aid of which M. Sainte-Claire Deville melts his platina so rapidly. The change results from the very rapid combustion of the carbon by the oxygen. As soon as this takes place, the flame, no longer containing any solid body, loses almost all power of emission, and ceases, in spite of its high temperature, to have the brilliancy which it possessed at a lower temperature. To convince you perfectly, let us put a solid body in this flame, now so pale, and you will see it become more brilliant than ever. We introduce, for example, a piece of lime, and the apartment is at once illuminated by the Drummond light, one of the most brilliant of our artificial lights.
But, leaving the earth, let us now return to the sun. The interior mass is undoubtedly at a very high temperature—so high, indeed, that all the substances composing it must be in the state of gas, possessing only a feeble radiating power; while the photosphere is composed of matter precipitated in a liquid or solid state, of which the radiating power must be considerable. Here is the explanation of what seemed paradoxical in my answer. The hottest part of the sun is not the part which warms and lights us most, because, being in the state of gas, it produces only a feeble radiation.
Two questions now present themselves. How is it that the sun preserves indefinitely so elevated a temperature in spite of the enormous amount of heat which it loses daily? Of what kind of matter is this luminary composed? And what the nature of the radiation which sends to us daily the light and heat which we need? It is undoubtedly impossible to give a complete and satisfactory answer to these questions. We may yet be able, however, to do so; and we are persuaded that science in its progress will only confirm and develop the explanations which we give to-day of first principles. In the first place, it is impossible to admit that the sun is simply a luminous globe, not possessing any means of renewing the heat which it loses at every moment; for, in that case, at the end of a few years its temperature would be lowered in a very appreciable manner; and it would not require an age to effect a complete change in the phenomena which are dependent on it. There must be, then, a source of heat in the sun.
We are in the habit of comparing things we do not know with those with which we are familiar. Thus we have been led to think of the solar globe as the seat of a combustion similar to that we witness on our hearths. This idea is deceptive.
We know the quantity of heat which each substance throws off in a state of combustion; we know, too, what a vast body the sun is; and we are able to calculate with a rough but sufficient approximation the quantity of heat which the body of the sun would produce in burning. The result of this calculation is, that, at the elevated temperature which the sun possesses, the combustion of the solar mass could not be kept up during many ages. Since the historic period this temperature would have been so lowered as to produce a change in the seasons that has not taken place. We are compelled, then, to abandon the idea of a mass in combustion, as well as that of a luminous globe, and to acknowledge that there is a secret which has escaped us.
This secret, gentlemen, chemistry is charged to unveil to us. Astronomers profit eagerly by all the discoveries which physical science makes, and it is by this means alone that they arrive first at conjecture, and afterward at a knowledge of what is taking place at prodigious distances. It is thus that the phenomenon of dissociation recently discovered by M. Sainte-Claire Deville, puts us in the way of explaining the permanence of the solar temperature. We know that no combination can resist heat. Whatever may be the stability of the combination, whatever energy the affinitive force may possess, if the temperature is raised to the proper degree, the elements separate, and remain together simply in a mixed state, wanting to combine anew when the temperature is lowered. This is what we call dissociation; and this is just the state, for example, in which we find oxygen and hydrogen gas, exposed to a temperature of 2500 degrees. At such a temperature they remain in a mixed state, without being able to form water, which ought to result from the combination of these two elements. But the phenomenon of dissociation cannot take place without the intervention of an enormous amount of heat. To illustrate this, let us suppose a kilogram of ice at zero. In liquefying it would absorb 79 degrees of heat; to make it warm, 100 degrees would be required; in evaporation it would absorb 640; and to dissociate it, 3955, or nearly 4000 degrees would be necessary. What we say of water is equally true of all the combinations; all that is required being to change the numerical degrees of the latent heat, for fusion, for volatilization, and for dissociation. This being so, we arrive at the conclusion that even the least considerable quantity of matter in a state of dissociation may be regarded as a magazine of latent heat continually tending toward sensible development.
The temperature of dissociation of water is almost 2500 degrees. The temperature of the sun being at least five millions of degrees, the whole mass of which it is composed ought to be in a state of dissociation, and to contain consequently an enormous quantity of latent heat independent of the sensible heat; to which is owing this prodigiously elevated temperature. What, then, is the effect which the solar matter ought to produce on the radiation of which it is the seat? Almost the same effect that radiation produces on a liquid body which has reached a temperature of solidification. The heat necessary to keep up the radiation is borrowed from that part of the liquid which solidifies, so that the temperature, instead of decreasing, remains constantly at the point at which solidification ceases. This is really what passes on the surface of the sun. This brilliant mass, raised to a temperature of five millions of degrees, has a tendency to cool itself rapidly. The radiation produces, in fact, a coolness in the superficial stratum. By reason of this coolness, part of the gas which composes the atmosphere is lowered below the temperature of dissociation; it yields then an enormous quantity of heat, which from latent becomes sensible, and prevents also an ulterior lowering of temperature. It is sufficient to repair the continual loss of heat that a mass of several kilograms passes daily from a state of dissociation to one of combination; and it is evident, considering the enormous size of the solar globe, that things may remain in this state during millions of ages without the temperature of the sun changing in a manner which may be felt by us. I say, by us, for our knowledge of this temperature is obtained at no less a distance than several hundred thousands of degrees.
It appears, then, from the very nature of the sun, that it does not possess an inexhaustible quantity of latent heat. A day will come when it will no more be able to lose heat without being cooled in a sensible manner, but that cooling will not take place before a very distant period, and long after we have disappeared from this world.
By way of recapitulation of the several views we have set forth, let us endeavor to give you a precise idea of the sun, as regards both its interior and its surface. The reasonings which we have just advanced, founded partly on astronomical observations and partly on known principles of science, lead us to regard the sun as composed of a fluid or gauze-like mass, surrounded with a photospheric stratum, the matter of which has passed through the first stage of condensation. According to the views held by Laplace, the sun proceeded from the hands of its creator in a nebulous state. We are led to believe that the interior mass is still in this state. A change has taken place only on the surface, because there only could the loss of heat owing to radiation produce a partial cooling. The result of this cooling is the condensation of a relatively small quantity of matter, which, possessing a very considerable power of emission, forms the photosphere. It is in the presence of this photosphere that the only difference exists between the sun and a nebula, between the myriads of stars which people the heavens, and the nebulae with whose existence the telescope makes us acquainted.
We come, at length, to the last with which we proposed to deal: What is the constituent matter of the sun? What are the elements which enter into the composition of its atmosphere and of the photospheric bed? Some years ago, to put a question like this would have been regarded as rashness; to attempt to answer it, the height of folly. We only knew, from the analysis of meteoric stones, that cosmical matter did not contain any other elements besides those of which our globe is composed. But to-day we can go further, thanks to the discoveries of the German Kirchoff.
We all know the solar phantom, and the brilliant colors which result from the decomposition of the white light. This phantom seems continuous if we make the observations in a rough manner; but if we employ delicate means, we see that it is formed of a multitude of black streaks and of brilliant rays perfectly distinct from each other. It is impossible to imitate this appearance artificially. All that we are able to do is to project on a screen the figure of a solar appearance taken from a drawing. You see that it is furrowed over with a considerable number of black streaks, of which the principal ones are, according to Fraunhofer, who discovered them, indicated by the letters of the alphabet, A, B, C, etc. These streaks are extremely numerous: we have counted no fewer than 45,000 of them.
I have said that it is impossible for us to imitate this appearance with our artificial lights, and it is precisely here that we are able to discern the nature of the different sources of light. In fact, each source has an appearance peculiar to itself, and by which it is characterized. The brilliant line of the Drummond light gives a continuous appearance, and it is the same with all the simple incandescents. But when we analyze the light of a body in combustion, we arrive at an entirely different result. The appearance obtained in this case is crossed by rays which, instead of being black, are, on the contrary, more brilliant than the colors in the midst of which they are formed. The same thing happens when we make the rays emanating from the electric light pass through a prism, because in this case there is combustion, that is to say, a combination of the oxygen in charcoals, mixed with foreign matter, from which is produced the voltaic bow. If we are content to restore these burning coals, they will give a continuous appearance just as lime.
The brilliant spectral rays are not always the same. They depend on the nature of the metal which is found in the flame, and which takes part in the combustion. You see at this moment the appearance which silver presents: it is characterized by a magnificent green ray. Here is now the appearance of copper, which, we know, has a yellow ray, accompanied by a fine group of green rays, different from those which silver produces. We now burn some zinc, which gives a magnificent group of blue rays, a fine red ray, and another of violet. Finally, we shall close these experiments with burning brass, which is, as you are aware, a mixture of copper and zinc. You will recognize in the appearance which is produced the characteristic rays of those metals, each of them producing its proper effect, as if it were alone.
We learn but little, however, from these experiments, of the nature of the substances of which the sun is composed; for the rays which we have produced are all brilliant, while those of the solar appearance are black. Let us see, then, in pursuing this subject, if it would not be possible for us to obtain these black lines with our artificial lights. Let us produce, in analyzing the Drummond light, a perfectly continuous appearance. Now, let us make this appearance, before reaching the screen, pass through a deep layer of hypoazotic acid. Immediately you see it discontinued. It is like the solar appearance, crossed over by a multitude of black lines. The hypoazotic acid is not the only gas that produces this result. The vapor from brome, that of iodine, will give equally the black lines in the same circumstances, only these lines are different from those we have just seen in the experiment made with the hypoazotic acid. Thus, the gases, the vapors, possessing the property of absorbing certain luminous rays, certain colors, these rays, found no longer in the appearance, are necessarily replaced by the black lines we have just observed. All the gases, all the vapors, could not, I am convinced, produce this result; for it is clear that their power of absorption, being less considerable, could not make itself felt, unless by means of a stratum the thickness of which should be greater than that which we are able to use in our experiments. We find a proof of this in what passes in the atmospheric air. Under a feeble thickness no sensible absorption is produced; but it is certain that the atmospheric mass absorbs a great number of rays, and consequently gives birth to many black lines; for in the solar appearance we observe new and very marked lines, when the sun being near the horizon, his rays pass through a bed of air of very considerable thickness. These rays are principally owing to the vapor of water. We can equally affirm the absorbent power of the atmosphere which surrounds the planets Saturn, Jupiter, and Mars. Their appearances contain lines very different from the solar appearance. Yet, as the light which they transmit to us comes to them from the sun, we are forced to conclude that that light undergoes some modification in travelling over its transparent path. It is the atmosphere of the planets which produces this result.
The sun also possesses an atmosphere, as we have seen, and this atmosphere ought necessarily to exercise an influence on the rays which traverse it. Such is, in fact, the origin of the rays which we notice in the solar appearance. They are owing to the atmospheric absorption, and the bed of transparent but absorbent vapor which surrounds the atmosphere, and which the rays pass through before they spread themselves in space.
But how are we to ascertain the nature of the vapors which produce the black lines we observe? Here physical science comes again to our aid, and the question we have just put finds its answer in a recent discovery. We have seen that a certain substance in burning gives birth to certain luminous rays which characterize it. We have also seen that this same substance, in a state of vapor, absorbs, on the contrary, certain rays, and produces in consequence certain black lines which are equally characteristic. Now, by a singular coincidence, these two powers, emissive and absorbent, are identically the same. Each substance, in a state of vapor, absorbs precisely the rays which it is capable of producing in combustion, so that the black streaks produced in the first case occupy identically the same place as the brilliant lines observed in the second. We may demonstrate this interesting theory by the following experiment, due to M. Toucault. We know that sodium produces in burning a beautiful yellow light. Well, let us burn some sodium in the coals, and between these two substances the electric light is produced. The metal while it is burning volatilizes largely; the vapors which are produced absorb precisely the rays which they should have emitted in their combustion; and you see that in the yellow, instead of a brilliant line, we have a very dark line. What we have just seen take place with the sodium has been equally proved by experiments on a great number of metals, and, by induction, we may extend the application to all those on which it has been impossible to make experiments.
Let us apply this principle to what concerns the light of the sun. The photosphere is composed of condensed substances, precipitated in a solid or a liquid state, floating in a transparent and absorbent atmosphere. This matter, being simply incandescent, ought to present to us a continuous appearance, and this continuity can be disturbed only by the absorption of the solar atmosphere. From this it follows, that to ascertain the chemical nature of the substances which compose this atmosphere, it will be sufficient to compare the black lines of the sun with the bright lines of our artificial lights. This has been done. M. Kirchoff first discovered that the sun contains sodium; for the line D of Fraunhofer coincides perfectly with the brilliant lines of this metal. It is equally well known that iron, copper, and twenty other substances which exist upon the earth in a solid state, would, at a temperature of five millions of degrees, be necessarily in a state of vapor.
After having thus made a chemical analysis of the sun, astronomers wish to go further; they have sought to know equally the composition of the stars. We have been led by this to some very remarkable consequences; we have been able to make a kind of classification of these stars, and to determine the group to which our sun belongs. It remains, then, for us now to apply the spectral analysis to the myriads of stars which stud the heavens, to those far distant suns, the greater part of which, perhaps, surpass in grandeur and brightness that which is the centre of our planetary system. It remains for us to interrogate these scarcely perceptible bodies, sparkling at such an incalculable distance, and to demand and draw from them the secret of their chemical composition. This enterprise is daring, but it is not rash. The difficulties are alarming; yet learned men are not discouraged, for they are accustomed to see difficulties disappear before strenuous and persevering labor.
We commenced our study of the stars with the complicated instruments which we employ for the sun; but we soon found out that this complication was useless. We have been able to reduce our instruments to the number of two, a cylindrical glass and a prism. And M. Wolff, of the Paris Observatory, has succeeded recently in suppressing the cylinder, keeping only the essential element, that is, the prism intended to produce the appearance.
We have examined a great number of stars, and I am going to submit to you some of the results at which we have arrived. You see at this moment the appearance which the star Orion presents. This star is of a yellow color; the appearance which it produces is deeply streaked; and it is one of the most beautiful in the heavens. You will find there the line D of sodium, and the line b of magnesium. These are two fundamental lines which have served as marked points to compare this appearance with that of the sun. Besides sodium and magnesium, a of Orion contains iron, copper, and several other known metals; but it is singular that hydrogen is not found there in the free state, as in the sun. There is, then, some essential difference between the stars, of which you will be more convinced as we go further into the subject. Here is the appearance of Sirius. You see it is not nearly so fine. You will find two large bands in blue, in the place of the streak F of the sun; two others in violet; and one, very faint, in yellow. The two first are attributable to hydrogen, and the last to sodium; but we know not to what substance the violet is owing. In the green there are also some very fine lines, but very difficult to seize.
What is most remarkable is, that all the white stars present the same appearances, and half the stars that are visible belong to this type. Thus the fine stars of the Lyre, of the Eagle, of the Bear, Castor, etc., ought to be ranged by the side of Sirius. There is, however, an exception in [zeta] of the Bear, which is a yellow star. The magnificent stars of Arcturus, of the Goat, of Procyon, belong, on the contrary, to the class of which our sun is a type, except that the iron line E is much more marked. Their color, of light yellow, led to the inference that they were analogous to the sun, and the supposition has been confirmed by spectral analysis. All know substances have an appearance which is peculiar to them, and which characterizes them. Can we say as much of the stars? Do they also present marked differences in their appearance? This has been the subject of very interesting researches. The task has been undertaken at the observatory of the Roman College, and it has led to a result altogether unforeseen, namely, that the stellar appearances appertain to only a very limited number of types. We may classify them in three groups. The first group is that of the white stars like Sirius; the second, that of the yellow stars, of which Arcturus and the second are members; and Orion may be regarded as a type of the third, in which we ought to place a of Hercules, and [Beta] of Pegasus. These two last-named stars have very remarkable appearances. They seem formed of a multitude of channels, which are divided by large black bands. This form of appearance shows us that the stars which belong to this type are surrounded with atmospheres heavily charged with vapor. In this group enters all the red stars, and in particular Omicron of the Whale, that celebrated star which has been called The Wonderful. Several small stars of a blood-red color have appearances resembling each other. It is remarkable that in all the appearances belonging to stars of this type, the black lines occupy the same place, which proves that in general they are all made alike.
I have observed further that certain types abound in certain parts of the heavens, and that the stars of the same kind are generally grouped together. Thus the white stars are found in the Pleiades, the Bear, the Lyre, etc.; the yellow in the Whale, Eridan, etc. The constellation of Orion deserves particular attention; it abounds in stars of a green color, reminding us of the nebula which is found in the same region of the sky. This small number of types, and the grouping of which I have spoken, constitute an unforeseen fact, the importance of which is considerable from a cosmological point of view. We should not, however, be hasty in drawing conclusions from it.
A curious fact has been established with regard to one of the white stars in Cassiopeia. Its appearance is directly the opposite of that which is presented by stars of the same color, for, in place of black lines, it shows some brilliant lines. This phenomenon has appeared to me so extraordinary, that I am anxious whether it is an isolated fact. I have observed more than five hundred stars, selecting some of the largest, and I have found only one, [Beta] of the Lyre, which possesses the same peculiarity. M. Wolff says that among the small stars of the Swan he has found some examples of the same kind. A most remarkable fact is, that these brilliant lines were found in a transient star which glittered for a time in the Crown in May, 1866.
These observations upset the theories which had been prematurely built upon facts formerly known. Still, there is nothing inexplicable here. You have seen that sodium burning gives a line of a very lively yellow, while the line becomes black if the sodium is increased to a considerable quantity. Might not the same thing happen with the hydrogen, which produces the brilliant lines of which I have spoken to you? Might not a small quantity act by radiation, while the action would be one of absorption should the mass be greater?
After having examined the stars, it was impossible to resist the temptation of observing the nebulae. You know that we designate by this name the kind of white clouds which are found spread in the heavens, and of which the nature is not perfectly known. Herschel has assured us that many of them, by means of the telescope, may be resolved into a multitude of small stars approaching very closely to each other. We infer from this that the greater part are composed in the same manner, and that the feebleness of our instruments is the only thing that prevents us from proving it. It is, however, admitted that many of these nebulae are formed of cosmical matter in a state of vapor not condensed. Everybody knows the nebulae which compose the Milky Way. But besides those which are visible to the naked eye, there is a vast number whose existence the telescope has revealed to us. One, of the most celebrated is that which is found in the magnificent constellation of Orion: we have carefully drawn it at the Roman College, and you see at this moment a sketch of it on the screen. The nebulae possess a very feeble light, and we had our doubts of success in seeking to apply the spectral analysis to them. We have, however, succeeded beyond our hopes. The appearances obtained in these observations are very singular. They reduce themselves constantly to luminous streaks, all the other colors failing; it is, in another way, that which happens when we burn an alcoholic solution with marine salt; the flame, analyzed by the spectroscope, gives simply a yellow streak. In the nebulae we find two green lines and a blue one. Such is the result which we obtained in examining the large nebulae of Orion, and that of the Milky Way in Sagittarius. Such is that, also, which furnishes the little nebulae called planetaries, on account of their form, which resembles that of the planets. These facts have been established for the first time by M. Huggins.
As I have just told you, the nebulas present generally but three lines; one belongs to azote, another to hydrogen, and the third is unknown. This result, which was not known before, is of the highest importance; for it teaches us that the nebulae are composed of gas and of vapors far removed from their point of saturation and condensation. These appearances, with luminous lines, distinctly isolated and separated from one another, appertain essentially to gas, and, we ought to add, to gas raised to a very high temperature. Thus we have made a discovery by the aid of the prism, for which the most powerful glasses had failed us.
The nebulae, notwithstanding their shining points, are not in general a collection of stars, but masses of cosmical matter in a state of dissociation under the action of an extremely elevated temperature. The collections of stars are perfectly distinguishable by the continuity of their appearances, as we see in the nebulae of Andromeda, and in some others which are well known. The discovery opens a vast field of investigation, and will be an epoch in science.
We have wandered far into the depths of space, very far from the point from which we started. This is of no consequence, however, for between the sun, the stars, and the nebulae there is a close relation. The sun is simply a star approaching nearer to us than others. According to a bold hypothesis, its entire mass was at one period in a state of dissociation, which a great part of it still actually preserves. The only thing that makes it differ from the nebulae, and causes us to rank it among the stars, is its superficial stratum of inconsiderable thickness.
What mysteries do we not discover in nature, when we investigate it by the aid of those principles and instruments with which modern science has furnished us! And in the presence of the wonders, what an exalted idea ought we to form of the splendors of the universe and the power of its Creator!
Permit me, gentlemen, in closing this lecture, to quote an admirable thought of Saint Gregory of Nazianzus. The sun, says that father, is the most perfect image of the Deity. You see the effects which it produces; you enjoy its benefits; but you cannot contemplate it directly, nor sound its depths. The loss of life, the greatest of the earthly blessings we enjoy, would be the punishment of the madman who would dare to invade its mysteries. It is the same with the Deity; it is impossible for us to see in himself; and we ought to content ourselves with admiring here below those traces of his infinite perfections which shine in his works.
We have succeeded, by the means with which science has furnished us, in examining this dazzling star, and in doing so we have seen some unexpected wonders; but how many other wonders have escaped us, which will doubtless be discovered at some future time!
If we can thus speak of the material sun and its splendors, what shall we not say of its prototype, when, freed from this material covering of sense, and reduced to a state of pure intelligence, we contemplate him with the eyes of our soul? Science and Faith are two rays issuing from the same focus, the one direct, the other reflected. As long as we are upon this earth we should be content with the second, our vision not being strong enough to support the brightness of the first. But a day will come when we shall see the Divinity face to face; and, in the meantime, the man who denies his unfathomable mysteries, under the pretence that our feeble powers are not equal to their comprehension, is as foolish as the rude peasant who should deny the wonders with which I have entertained you, under the pretext that his eyes are dazzled by the light of the sun. A day will come when the direct rays of the Science of Divinity will no longer dazzle our intelligence: the high destinies which awaits humanity will permit of our contemplating the unclouded essence of the Deity, as the reward of the persevering but not blind fidelity with which we shall have here below, without pride as without baseness, believed in his existence and admired his greatness.
Translated From The French.
An Italian Girl Of Our Day. [Footnote 155]
[Footnote 155: Rosa Ferrucci: her Life, her Letters, and her Death. By the Abbé H. Perreyve.]
Continued From Page 372.
I here interrupt, for a moment, the order of these Letters, to introduce a fragment from one of the writings of Signorina Ferrucci, in which is found, eloquently developed, the idea with which the last letter closes. Need we wonder that, to so a pure a soul, Christianity was all mercy and all love? Certainly not. The passions of men have so often disfigured the sweet countenance of the gospel that those outside the household of faith form a false idea of it, and, in their inability to distinguish what is divine from what is human, they reject all. But, if they would only learn to leave men and draw near to God, to flee vain disputes and go to the centre where all is calm, they would soon know that the genius of Christianity is indeed love. Pure souls, whom anger and dispute have not marred, know this well. The young author whom I am about to cite understood it, and it is with a feeling of respect that I transcribe these beautiful pages, which breathe so strong a perfume of the gospel:
The love of God, which inflames the heart of man and infuses into it a holy zeal, has assuredly nothing in common with that implacable fanaticism with which infidelity so unjustly charges the religion of Jesus Christ. And yet it is but too true that the sons of one Heavenly Father, the inhabitants of a world watered by the Redeemer's blood, have more than once, while waging cruel war upon each other, ranged themselves under the standard of the cross. But because such horrors darken the page of history, are we to conclude that the love of God banishes all toleration from the human heart, or can we deny that the Catholic religion is all love? And shall the blind fury of men make the world forget the numberless benefits which, for nineteen centuries, the gospel has bestowed upon all nations and upon its most cruel enemies?
O church of the Redeemer! who dost pray for thine enemies, and dost show thyself ever ready to succor them, even as our Heavenly Father maketh his sun to shine upon the most ungrateful of mankind, who was it that filled thy heart with that holy and ever active love of all the virtues? Who gave thee the strength to oppose at all times a tranquil front to the masters of the world? Whence have thy martyrs derived that courage which made them joyfully bend their heads under the axe of the executioner? Who taught thee to confound the subtle contradictions of the philosophers, and, with the same hands, to break the chains of the slave? How is it that, ever firm and immovable, thou alone hast survived the vicissitudes of all things and the overthrow of so many thrones? Who has given thee such power of persuasion that by its prodigies "from the very stones are raised up children to Abraham"? In fine, whence hast thou received that inviolable authority which resolves all doubts, dissipates our errors, humbles the mighty, sustains the weak, enlightens the world, pardons all faults, and consoles in every affliction and in every distress?
Ah! who does not see that so many miracles have been wrought by the sole power of that divine love kindled in thee by Jesus Christ? For just as thou lovest Jesus in fatigue and in repose, in tears and in joy, in persecution and in peace, in combat and in victory, so also thou lovest in him and for him the humble and the great, the faithful and the unbelieving, the poor and the rich. There is not on this earth a human being for whom thou dost not pray, and whom thou wouldst not, at any price, bring back to the bosom of him who suffered for all men because he loved all. Oh! may thy desires soon be fulfilled, holy church of the living God!
How, then, can that man call himself the friend of God and the true son of the church of Jesus Christ, who would oppose arms to arms, violence to violence, forgetting these words of Christ, "Love your enemies," "Father, forgive them, for they know not what they do"? The blind apostles of intolerance show well that they have never penetrated in its true sense the life of the Redeemer, who, suffering every injury, and even the death of the cross, drew the whole world to himself by the irresistible power of pardon and of love. He who would be willing to forget his prejudices, and, retiring into the solitude of his own heart, would plant there the sweet image of Jesus Christ, such a one would soon learn how far the power of Christian meekness transcends that of the sword, and he would shudder at the thought of pursuing with fire and steel them whom the cross alone may vanquish. Ah! if Jesus crucified entered truly into our hearts, how many things would he not make them understand! [Footnote 156]
[Footnote 156: Della Carità Cristiani.]
Again, I find, in the same paper, this beautiful sentiment:
I believe that charity consists not solely in compassionating the sufferings of the poor and relieving them. Its character is more general: it must be the soul of all our sentiments. For my part, I see charity in patience, in humility, in faith, in docile submission to superiors, in justice, in courage, in fortitude, in contempt of the world, in the desire of heaven. Charity is, indeed, the light of God, infinite as himself. Whoever has received into his heart a ray of this divine light is bound, if I may so speak, to communicate its warmth to the whole world.
We return to the letters.
July 15.
Sweet were the impressions, Gaetano, which our walk yesterday in that beautiful garden left on my mind. Is it not true that the flowers, the trees, the blue sky, the pure soft air, the song of the birds, the hum of the insects—all conspired to speak to our hearts of God? I feel, too, that all these beautiful things seemed more joyous to me because you were there, for to me they all seemed to reflect the feelings of your heart. Then those beautiful verses of my mother's which Uncle G—— read to us affected me powerfully. Earth and heaven, flowers and songs, all borrowed a new charm from the harmony of those beautiful stanzas.
July 22.
I do not know the places you speak of, unless you mean Romito and Antignano. I went as far as La Torre on foot, one beautiful August morning, without suffering much from the heat, which was tempered by the sea-breeze. After having traversed that long, steep road, which becomes at every step more solitary and more closely shut in between the hills and the sea, I went up to the top of the little fortress, and thence for a long time I gazed on the neighboring islands and the vast horizon where sea and sky seemed to unite, and I even discerned some of the lands of the Maremma. Another time, with the Plezza, the Gabrini, and other friends, we went as far as Romito. The sun had already sunk below the horizon. Every moment the last glimmering of twilight was becoming more faint, and soon the moon rose behind the hills. Her pale rays were reflected in the sea, where nothing was seen save a solitary fishing-boat; and the gentle murmur of the waves, as they came slowly to die on the rocky shore, was the only sound that broke the stillness of the night. We crossed from time to time the dry bed of one of those torrents which fall from the mountains into the sea; and thus, now talking, now silent, gazing, admiring, we passed the two little towers, and, arrived at the limits of the two communes, we stopped and turned back, as if we had reached the Columns of Hercules, There is a comparison that would please my good friend Louisa V——. Would you believe it, in her last letter she gravely compares me to a navigator steering toward a new world. "Yet no," she says, "love is a world as old as the earth." That may be, my good Louisa; but to me it is new, all new, Gaetano, and I believe, even, that it will never grow old, like everything that comes directly from God, who is endless duration in eternal youth! On this is grounded my sure hope that, after having united us here on earth, he will unite us again in the life to come; and this thought alone raises me from earth to heaven!
This was not the first time that Rosa had visited Antignano. That calm and lovely shore had witnessed the sports of her childhood. Three or four years before the date of the last letter we have given, she wrote from that place to one of her young friends the following pretty letter:
Antignano, July, 1853.
In spite of our joy at being here, believe me, my dear Maria, we feel your absence sadly. It turns to melancholy the joyous memories of last year. This is from my heart, Maria; how happy I should be to have you at this moment by my side! Come back to us then, dear friend, come back! The little wood where we spent so many happy hours, the great shady trees, the smiling country, and the sea—all call you back. Why, it is but two days since I heard a wave which came bounding over the sea say to you, "Come down, young girl, from the flowery bank into this calm sea, and yield to the invitation of the sun, who with his brilliant rays is brightening air and earth and water." But this pretty song of the naiad was suddenly interrupted, for my poor wave broke and expired on a rock. All its sister wavelets murmured the same prayer to you, but all, like the first, soon broke upon the shore; and I grew pensive at the sight, for those poor waves, vanishing so quickly, seemed to me a true image of our shattered hopes, which cause us so many tears. Meanwhile a little interior voice remained with me, and murmured sweetly in my ear, "Courage, courage! Why are you sad? Cannot Maria come back? I am your good friend Hope, listen to me and believe me: I promise you that next year Maria shall be here." This consoled me a little, for I always believe what my good friend Hope tells me. Courage, then, and patience, and I am sure of having you yet at Antignano. Dear Maria, pardon this letter, which is as long as it is foolish, and, if you do not understand it, seek in it only a new proof of my tender affection for you. Meanwhile, let us leave the world of dreams and enter that of news. ...
To Gaetano.
July 28.
This day brings to us a mournful anniversary. Poor Charles Albert! on this day, and at the very hour in which I write, he yielded up to God his soul, oppressed with grief, but still full of an unshaken confidence in the justice of his cause and the imprescriptibility of his rights. Doubtless the saints have welcomed into heaven him who on earth loved God and suffered for justice' sake. It is with feelings of compassion that I think of the king, his son, surviving all his family, who have, one after the other, gone before him to the grave.
This enthusiastic remembrance of the house of Savoy is not the only one to be found in the letters of Rosa Ferrucci. The misfortunes of the king, Charles Albert; the death of the Duke of Genoa, his son; the ruin of so many hopes, for a moment triumphant—all these often call forth in her correspondence plaints and regrets. I like to see this love of national independence in so pure a soul. She says somewhere:
"In considering the history of nations, we discover at every step new and infallible proofs of the wisdom and omnipotence of him who directs the affairs of the world; of that mysterious justice which surpasses all human understanding as the heavens surpass the earth. Hope, then, in the Lord, ye victims of oppression! Acknowledge the hand which alone can give you deliverance! And you, usurpers of the rights of the vanquished, triumph not without trembling at the tears which you have caused to flow. He lives, he will live for ever, who will never remain deaf to the lamentations of his people Israel. If he defers his justice, are you to cease to believe in him? Because he can wait, will your presumption know no bounds? Do you forget that God is patient because he is eternal?" [Footnote 157]
[Footnote 157: Della Carità Cristiani]
Patriotism was, however, a family tradition with Rosa Ferrucci. At the time of the memorable events which, in 1848, threatened the speedy overthrow of Austrian rule in Italy, Signer Ferrucci, with his colleagues in the University of Pisa, quitted his chair, and, at the head of the students, who had formed themselves into a body, set out for the army, accompanied by his young son. They took part in all the battles of that unfortunate campaign—at first in its victories, then in its reverses—and returned to Pisa only after the ruin of the last hope. These are facts too little known in the contemporary history of that unhappy Italy whose faults are the theme of every tongue, while few know how many noble hearts she can still produce.
We resume the correspondence:
August 4.
May I tell you, Gaetano, what I have been thinking about our future life? We must first, as we have so often said, have continually present to our minds the will of God, endeavor to accomplish it in all things, and be ever submissive to it from our inmost hearts. Then we must have but one heart and one soul in serving God, and I hope that we shall have but one heart also in loving our dear parents. What ingratitude would be ours if in our happiness we forgot them to whom we owe so much, and who loved us before we knew what love was! [Footnote 158]
[Footnote 158: "Prima che noi potessimo sapere che fosse amore.">[
Let us endeavor so to regulate the affections of our hearts that one shall not be stifled by the other, but that all, forming a sweet harmony, may rise toward him who created us, and for whom alone we must live. May he alone be the end of all our actions and of all our thoughts! Then fatigue will never overcome our courage, our duties will never seem too heavy, our life will be calm, our intentions pure, and we shall taste even here below that interior peace,
"Which no one knows but he who feels it."
Such is the plan of our life. I have but lightly sketched it, fearing that I might seem to be giving counsels and prescribing rules to you. All this is possible only by the grace of God. Let us beg it through the intercession of the Blessed Virgin at the approaching festival of the Assumption; we have so great need of her protection and guidance.
"We pray for grace and it obtain
From her who is its mother."
September 15.
To-day I am as sad as I was joyous yesterday. Your departure, the thought of an inevitable separation from my father and mother, a thousand conflicting feelings in my heart, undefinable to myself, have made me weep. Alas for us women! we are weaker than the leaves which are stripped from the trees and scattered by the first wind of autumn; and, childhood scarce passed, our hearts, capable only of loving and suffering, are torn by a thousand contrary emotions of joy and sadness. Pardon me these murmurs, O my God! No, I ought not to weep, but ought rather to pour out my soul in thanksgiving.
I open my whole heart to you, Gaetano, because it is you who are to be the support of my life; to share all my thoughts, dispel my fears, and be my counsellor and guide. Singular thing! my new hopes have made all my feelings more keen and ardent. Hence those alternations of joy and sadness, to whose deepest emotions I was till lately a stranger. As it is, I do not know how I am to tear myself from the arms of those who watched over my childhood and who love me so much. But let us forget all this to-day. I can no longer speak of my mother without my eyes filling with tears. It is drawing near that dear October. If I cannot enjoy your ruralizing, I can, at least, be happy in thinking of the pleasure you will find in it. You are going to see your mountains again, and those pine-groves, which from my childhood I have ever loved and admired. In the midst of the flowers, the plants, the trees, you will think often of him who created us with souls capable of loving the beautiful and good; of him who this year has opened to you the horizon of a new life, in which I hope you will never find either regrets or thorns. Oh! how easy, as it seems to me, does the beauty of the country make the love of God. How sweet it is to think that the same God who gives the dews and the fertilizing rains to the earth, foliage to the trees, flowers and harvests to the fields, is also that loving Father who supports us in all our trials and so sweetly invites our souls to repose in himself! Let me speak to you of the good God, Gaetano; I love so much to think of him.
September 25.
I cannot express the pleasure it is to me to gaze into the deep azure of the beautiful mornings of which
"The air is sweet and changeless,"
and of the lovely evenings when the stars seem to speak, and tell in a sacred language the wisdom of God. The country does good to our souls. In admiring its beauties and its treasures ever new, we are led more easily to think that, if earth was made for man, man was created to love God. I often say to myself, What, then, will heaven be, if there is so much of beauty on this poor earth, where we are not so much dwellers as pilgrims? ... On the eve of St. John's day, all Florence was illuminated. There was nothing to be heard but games and noisy laughter among the people. Every one was gazing eagerly at the fireworks and the illuminations; but no one thought of admiring the most beautiful ornament of the feast—I mean the moon, whose tremulous rays were reflected in the Arno, lengthening the shadows of the trees.
September 28.
Next year we will go to the country together. If you knew how I love your mountains, with their tall pines, their flowers, their streams, and their green summits. I still remember the moment I left them. It was a November morning. The faint rays of a cloud-veiled sun shed a pale light on the horizon, the leaves were falling from the trees, and the snow of the day before still covered the summits. All nature was solitary and sad. Who could have told me then, that to this melancholy spot which I was leaving as a child, I should return with you a happy bride?
October 23.
Enjoy well your ruralizing; its pleasures are a thousand times sweeter than those of our towns. How pleasant it is of an evening to climb the heights, and thence behold the vast expanse of heaven still purpled by the sun's last rays; to see at one's feet the fields, the pine groves, the pale olives, the elms, yellow-tinted by autumn, the little, scattered cottages of the peasants, with the smoke of the evening fire rising from the roof, and the village church, which seems by the tolling of its bell "to mourn the dying day,"
"Il giorno pianger che si muore!"
[Transcriber's note: This sentence is blurred.]
I am far from all this now, but I often think of it. Again I see our happy day at Cuccigliana, our mountain walk, and that beautiful horizon, with its luminous depths, which promised me a joyous future. How many things nature can say! How she can speak to the heart! How, above all, she can speak to it of God! Flowers, hills, forests, earth, and sky—all are more beautiful when we have learned to discern in them the beauty of God. How many times already, Gaetano, have I gone over again our walk on the Serchio, where the rustling of the leaves was the only accompaniment to our long conversations! Ah! may God bless thee, may he render thee happy, and all my desires will be satisfied.
Eve of All Saints' Day.
Oh! if the feast of to-morrow should one day be our feast! Do not suppose, however, that I am presumptuous enough to hope that we shall ever be like the saints of our altars. No; but I believe that not only those great saints, but also all the souls of the just who are admitted to the beatific vision of God, are invoked on this great day by the church. This it is that emboldens my desires. ...
If you are sad, recollect that it has pleased God thus to alternate in this world our joys and sorrows, in order to implant more deeply in our souls the desire of that life in which weeping shall be no more. Then shall we be united I hope, in the love and blissful contemplation of that God whom we now adore under the veil of faith.
Meanwhile it is sweet to say to one's self: God loves me infinitely more than I can love myself. He thinks of me and watches over me with a tenderness surpassing all the tenderness of a mother. What, then, should I fear? And besides, how be Christians and not be willing to suffer for love of a God who has suffered so much for us? I would share these thoughts with you, Gaetano, because I find in them my strength and consolation every day. Treasure them in your heart, call them often to mind, and your sadness will disappear as
"La neve al sol si disigilla." [Footnote 159]
[Footnote 159: "The snow dissolves before the sun.">[
I do not think we shall lose by the exchange when, having finished Milton, we read Virgil together. That great man seems to me indeed
"The light and honor of the other poets,"
as our Dante says. We shall reap from this reading the great advantage of being able to compare the principal episodes of the AEneid with the best passages of other poems. I assure you I do not regret the time I give to my little studies; if I had to commence them again, I should apply myself only with more diligence and attention. I owe to them the best pleasures that I have known; above all, I owe to them community of intellectual life with you. [Footnote 160]
[Footnote 160: I would for a moment call the reader's attention to this sentiment. Such should, indeed, be the chief end of the studies of every Christian woman—community of intellectual life with her husband, community of intellectual life with her sons.]
Now that I do not take lessons, and that, consequently, I have no more leisure, I know no more lively pleasure than to shut myself up in my little room with my books and my pen; and even during those hours which I ought and which I am determined to devote to needlework, I love still to think of what I have read and to beguile the time by these pleasant memories. Having had some time for study to-day, I resumed the reading of Muratori, taking the history of the wars of Odoacer and Theodoric. The subject is a familiar one, but I return to it always willingly, because I think the history of the middle ages even more important for us to know than ancient history. And then what joy of soul to see the church, in all places and in the most barbarous ages, the mother and guardian of civilization, the friend and consoler of the vanquished, the last bulwark of the oppressed against the unbridled pretensions of power!
Poor Italy! how she has suffered! What carnage! How much blood shed in vain! How many tears!
January 1, 1857.
Let us pray God, let us pray him with our whole heart to-day, Gaetano, to bless our union, our souls, our actions, our thoughts, our life. May he deign to preserve long those who are dear to us, to shield us from great misfortunes, and, above all, never to withdraw his grace from us! Such are the prayers that we will offer together, united in heart, though separated by distance. God will see the sincerity of our desires, and he will grant them.
The serenity of the heavens gladdens all nature, and rejoices also our souls, which in the light of the sun seem, as it were, a reflection of the Increated Light. I do not think I am superstitious, Gaetano; and if the new year had commenced in the midst of lightning, thunder, and dismal rains, I should certainly not, on that account, have augured ill for our future. But now, contemplating the calmness and pureness of the sky and of the whole horizon, I ask of God to give us a life like to this beautiful day, that is to say, such a life that nothing may ever be able to disturb in our souls that peace whose source is in God, its eternal fount.
January 4.
After some cold days, the weather has again become very mild, and the air is balmy as with the first perfumes of spring. How brightly the sun shines to-day! Its warm beams inundate my little room. Seated at my table, at some distance from the window, my eye wanders involuntarily to what I can see of the sky. I fancy I see a great blue eye looking down lovingly on me. Ah Gaetano! how good is God!
I have just learned the death of a very dear friend. Young, beautiful, brought up in opulence, the only daughter of a mother who idolized her, she wished to become a Sister of Charity in order to serve God in his poor. For ten years she has been a tender mother to the orphan, and she has just died in the bloom of her days. Dear and good Sister Maria! how happy I should have been to see her again! I do not cease thinking of her! Schiller would say here: "Cease to weep: tears do not resuscitate the dead." Ah! with what a far different power do the words addressed by the Redeemer to the afflicted come home to our hearts: "Blessed are they that weep, for they shall be comforted!" The more I meditate on these words, and then look on earth in its renewal, the pure light and deep azure of the sky, the more I am impressed, death notwithstanding, with the infinite goodness of God and the ineffable bliss of a future life. I hear sometimes of the good being oppressed by the wicked; I often see virtuous persons in misfortune; will not, then, the just also have their day and their recompense? Ah! often, when at night I raise my eyes toward the twinkling stars, I think of those happy souls who are there on high, higher than the stars, in the eternal enjoyment of the beatific vision, of adoration and love without end. If man would only fix his soul on such thoughts, what is there on earth that could discourage him?
I received your dear letter this morning, Gaetano, and lest you should suppose I thought it too gloomy, I must tell you that I, too, have been thinking of death the whole day, and that I even offered a special prayer to our Lord to be merciful to me when the hour shall have come for me to pass from time to eternity, and, as I hope, "from the human to the divine." We have need of abandoning ourselves with a child-like confidence into the arms of God, if we wish to keep alive in our hearts the hope of seeing in heaven him whom we adore on earth. For my part, if, instead of thinking of him alone, I turned to think of myself, I really know not whither my reflections might lead me. But hope, which is a Christian virtue, is a firm expectation of future glory, I will, then, forget my fears and believe that, despite our imperfections, we may one day taste in the bosom of God a happiness even of the shadow of which we cannot catch a glimpse on this earth. We shall then know in what overflowing measure the Lord rewards even the feeblest efforts of his friends. We shall know how everything here below was inevitably passing away with ourselves, how this earthly life vanished more lightly than a dream, and that there remains nothing to man after death but love, that ethereal part of the soul which God claims all for himself. Yet more: I believe that the love which shall unite and commingle our souls on high will not be absorbed in the contemplation of the divine essence in such a manner that the sweetness of loving each other still shall escape our perception. I believe, on the contrary, that it will be the triumph of love to exist and to endure in God, and to unite in one canticle of praise the souls which God made to love one another.
More sorrow—Matilda is dead! [Footnote 161] Oh! how we loved her. She was an angel! It is we only who suffer, for to her it is pure happiness to have quitted earth. Not a murmur was ever heard from her lips. She found all peace and all strength in the love of God. Her soul so easily opened itself to joy. The day before her death, seeing some flowers, "What beautiful things our God has made!" she exclaimed. Her friends wished to inform her father of her imminent danger. This she constantly opposed, wishing to spare that poor father the agony of a last farewell. Here are examples.
[Footnote 161: Matilda Manzoni, daughter of the celebrated author of I Promessi Sposi.]
I do not know the introduction you speak of; but my mother has read to me the admirable verses of Manzoni which are prefixed to it. How many things these verses recall to me. They have affected me powerfully. Returning in memory to the times that are past, I fancied as I listened to them that I heard the sweet voice of my poor Matilda, who, in reciting this beautiful poetry, evinced so tender an admiration for her father's genius. We were at Viareggio. It was a beautiful summer evening, and the peace of a starlit sky penetrated deep into our souls. Matilda said to me: "Rosa, if you could only tell me the first verse of those stanzas, I am sure I could recite the whole." For some time I ransacked my poor memory in vain. Suddenly came the word, "Pause awhile." That word was enough. Matilda recited without failing in a word—and oh! with what feeling—the whole piece of poetry. Dear friend! she is with us no longer, and we shall see her no more on earth. When I parted with her last, I said to her: "Farewell till we meet again." I ought to have said: "Farewell till we meet in heaven."
When the storm came upon us, [Footnote 162] two terrific peals of thunder were heard at once. I confess, Gaetano, I did not expect to reach Pisa. And oh! how terrible is the thought of death, when all around reminds one of the almighty power of God. I trembled as I thought of eternity. I saw my own nothingness, and that my only refuge was in the bosom of God. There did I cast myself with all the confidence of my soul. Unperceived by any one, I drew from my bosom my crucifix, and, concealing it in my hand, I pressed it to my lips. I felt then what help religion will give us in our last moments, for I immediately regained courage, and all my fears vanished.
[Footnote 162: Signorina Ferrucci was, with her parents, returning from Leghorn to Pisa, when they were surprised by a violent storm, which is the subject of this letter.]
To Signorina Louisa B——.
I received your sad and tender letter yesterday, my dear Louisa, and I answer it without delay, to prove to you that your sorrows are mine. Poor Antonietta! Yet, why weep for her? Her soul has winged its flight to the celestial regions, where, as she said in her delirium, all was ready to receive her. It is not to her, then—it is to you, to your family, to ourselves, that our tears belong. As soon as I heard the sad tidings, I raised my heart to God, and offered him a fervent prayer for your mother and yourself. As to Antonietta, I could not pray for her, because I saw her truly in the midst of the angelic choirs.
Dear friend, would that I could console you; but I feel with sadness my utter inability. It is God alone who has the secret of true consolation. Is not he our good Father? Does not he await us in that blessed abode where there are neither sorrows nor tears, but where reign eternal peace and happiness? And then, my poor Louisa, if life seemed to promise your dear sister happiness and joy, has not death put her in possession of joys more pure, happiness more profound, than she could ever have desired? Oh! how enviable is her lot. She will never know the troubles, the disappointments, the disenchantments of this life. She will be spared all the suffering which is inseparable from a long existence. Death has been to her a beautiful angel, come from heaven to crown her with flowers. Dry your tears, Louisa: your sister is happier than we.
To Gaetano,
Each day is bringing you nearer the mournful anniversary you spoke of in your last letter. I beg, I conjure you, Gaetano, to allow to your heart no sentiment but that of resignation. Remember that we shall see in heaven those who are taken from us on earth; and that the sufferings of this life are the means by which we are to attain endless beatitude. I speak thus, not to preach patience to you, which it would ill become me to do, but to give you a word of consolation; for I know all that you have suffered, all that you still suffer in secret. The cares of business and the multiplicity of exterior duties will not prevent sorrowful memories from taking possession of your soul. You can, then, but offer your sufferings as a sacrifice, believing that they will render us more worthy of the divine love. If I already shared your life, I would do everything in my power to console and encourage you on these sad days. Meanwhile let us both strive each day to lessen our imperfections, and to let the love of God have fuller scope in our hearts. Thus shall we, if not without fear, at least without remorse, reach that solemn moment of our life, the one that will end it. May God, who, we hope, will one day unite us on earth by holy ties, deign to unite us also in heaven!
January 21.
(Three days before the commencement of her illness.)
Truly we must be always ready to die when and as God wills, and to love him infinitely more than all the things of this world which are passing away with our frail lives. Our immortal soul is not made for this world, where all is fleeting, dissolving, changing. By the very nature of its being, it yearns for heaven. For me, living or dead, in this world or the next, I will be ever thine, my Gaetano, in the love that God knows and blesses.
This letter is the last that Rosa Ferrucci wrote.
Concluded In Next Number.