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when he just sees the dark spot completely round, is done, a curious result is brought to light, he notes the time indicated by his chronometer, namely, that one of the observers has seen Venus and records the hour, minute, and second. Half on the sun for a longer period than the other. It his work is now done, and during the four or may be, perhaps, that at one station the transit five hours that elapse while Venus is moving lasted three hours and three quarters, and at the across, he has nothing to do; but when the other, four hours and a quarter, giving a differplanet draws near the other edge of the sun, ence of half an hour between the durations. The preparatory to quitting it altogether, the observer exact times depend on the precise localities chosen ; again seats himself at the instrument, he fixes his but it is probable that in the coming transits the gaze steadily on the black round spot as it nears stations selected will be such as to make the differthe edge; gradually the portion of the sun be- ence nearly half an hour, this is about as great tween the planet and the edge becomes smaller, as will be practicable, and it is desirable to have and dwindles down till, when the planet just the difference between the intervals as large as touches the edge, he glances again at his chro- possible. nometer and again notes the hour, minute, and second. He has then ascertained the time at which the planet was first completely on the sun, and the time at which it began to move off the sun, and by knowing these times he is able to find how long Venus took to pass across by simply subtracting the latter of these times from the former. This interval of time is the important matter to know; it is the object of all the trouble which the observer undergoes.

But one observer, making the observations in one particular place, however skilfully he may perform his part, cannot yield us sufficient information to enable us to solve the

It will doubtless occur to our readers to inquire, What is the cause of this difference? and a little attention will be necessary in order to understand it. This is a most essential point in the process of determining the distance of the sun. It will,

Fig. 3.

grand problem of the distance of the sun from the earth. In some distant quarter of the globe -in a place separated by thousands of miles from the station of our observer, must another observer be at work. He must be similarly equipped with telescope and chronometer, and, what is of hardly less importance, with equal skill and patience. Then, from a different continent, and under a different clime, he, too, must note the precise moment at which the planet enters on the sun by his chronometer; he must note also the precise moment at which she commences to leave the sun, and then, by subtracting these times, he will learn how long from his point of view Venus remained on the sun. This being ascertained, and the latitude and longitude of his position being accurately known, the object of his long journey is accomplished, he returns home bearing with him the precious memorandum of his observations.

The next stage in the process is to compare the results of the two observers together. When this

perhaps, be made clear by an illustration.

Suppose that we are looking at a landscape, we see some distant objects, perhaps houses, or trees, or mountains, that form a sort of background to the objects which are nearer us. Let us fix our attention on some object, suppose a tree, which lies near where we are standing, and let us notice how this is situated with reference to the background. Let us sup

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pose that from where we are stationed there appears far away a house, which seems to be behind the tree and directly in a line with it. Now, let us leave the station which we have been occupying, and move to another. If we look again at the tree, we shall find that it is no longer in a line with the house, and that its position, with reference to the background, has changed. Here our change has caused an apparent change in the position of an object in the foreground with reference to the background. A landscape is not necessary for the observation of this simple fact. If we look through a window and notice the parts of the background which are close to one of the bars which separate the panes, then if we move our heads we can see that the bar has apparently moved away from its former position with reference to the background. If we make our experiment from a house in a street, the front of the opposite house forms a good background, and in this case it will be well to use only one eye, as the position of the bar with reference

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to the opposite house will then be more easily is furnished. He fills many sheets with calcula

seen.

Let us now apply what we shall have thus learnt to the case of the transit of Venus. Here the planet is the object in the foreground, while the sun forms the background. Supposing that the observer at one station sees Venus in the position marked P (Fig. 3); it will to him appear to move across the sun along the line A B. But just as in the case already described the window-bar appears to be in front of different parts of the opposite house from two different positions of the eye that looks at it, so Venus appears on a different part of the sun to each of the observers, since they are in different positions. If, then, the second observer sees the planet in the position Q (Fig 3), it will to him appear to have described the line c D. Now we can understand why the transit will have lasted longer when viewed from one place than the other. To one observer it appears to have moved along the line A B; to the other it appears to have moved along C D. But the latter line is evidently longer than the former, and therefore from the latter station the transit appeared to last longer.

After this point, the difficulties of the subject begin to throng more about our path-so much complicated reasoning has to be gone through, so many allowances have to be made, so many circumstances attended to, that we are unable in the present article to do more than indicate the course which must be pursued.

tions; employs numerous checks to guard against inaccuracies; laboriously but patiently he proceeds to the end, and finally emerges from his chamber and announces to the world the distance of the sun from the earth. Every one can understand the materials which the astronomer uses; every one can understand the result at which he arrives; few only can follow the necessary chain of reasoning.

When the joint result of the labours of the observer and the calculations of the astronomer has been announced, even though we may not be able to follow the steps which have been taken, it yet becomes us to accept with confidence the result they have arrived at, as our tribute to their industry and skill.

The last transit of Venus occurred in the year 1769, and the necessary observations were made for determining the distance of the sun on the occasion. It was deduced to be about ninety-five millions of miles from the earth! A little consideration is necessary to fully realise how enormous is this magnitude. Suppose that a locomotive engine could travel a thousand miles a day and that it kept up this rate, it would have to travel for two hundred and sixty years before it would have traversed a distance equal to the distance of the sun from the earth. The sun is nearly four hundred times further from us than the moon, and this is the reason why, though it really is very much larger than the moon, it yet appears about the same size.

The distance of the sun which was determined by the transit of 1769 has until lately been thought to be very accurate; but within the last few years an idea has gradually been gaining ground among astronomers that the estimate is a little too large. To understand the source of this doubt it is necessary to remember that there are other less accurate ways of finding the distance of the sun besides that afforded by the transit of Venus. Some of these may be mentioned. There is, first, a series of observations on the planet Mars, from which the distance of the sun may be inferred by the calculating astronomer; there are, secondly, some circumstances connected with the moon's motion, which enable us, by means of observations on the moon, to determine-what may seem strange-the distance of the sun; besides these, there are others known to astronomers, which need not be entered into here.

The observers have now done their work, each of them knows the precise latitude and longitude of the place from which he made his observation, and the time that from his point of view the transit occupied. To do well the work that they have done requires skill; but they have not been called on to exercise any of the highest intellectual powers which have yet to be brought in action. The aid of the astronomer in the highest sense of the word is now invoked. He may have taken no part in the observation; he may not even have seen the transit; his life may have been spent more among books, papers, and figures, than in contemplating through telescopes the glories of the sky, but his assistance is not the less indispensable. To his hands the observers consign the results they have obtained; to him these figures contain a deep significance. It is hard for us to see how from such materials the distance of the sun is to be inferred with accuracy. The astronomer's own labours and those of his predecessors These subsidiary methods have latterly become have taught him how this is possible. Into the entitled to our confidence, in consequence of the mysteries of the process we cannot enter; they perfection which astronomical instruments have would only be intelligible to those who have under- reached, thus rendering the observations very gone the labours and enjoyed the privilege of a accurate; while at the same time there has been a mathematical education. The astronomer combines corresponding improvement in the methods by the figures he is given with others that he finds which, from these' observations, the results have in the tables and books with which his observatory | been inferred. All these, which we have called

BABY JEANIE.

the subsidiary methods of finding the sun's distance, agree in indicating that about ninety or ninety-one millions of miles is nearer the truth than ninety-five millions of miles, which was the estimate deduced from the transit of 1769.

To this it may be objected that the subsidiary methods being admittedly less reliable than the transits of Venus, why do we not, when a discrepancy arises between their results, adhere unhesitatingly to the latter and more accurate method? The answer to this is easy. The transit took place a century ago, and though the excellence of the method was then as well understood as it is at present, yet experienced observers were more rare, and astronomical instruments were less perfect then than now, and, in fact, it is pretty generally believed that there were certain wants of precision in the observations of 1769, which cast a doubt on the correctness of the result deduced from them.

The state of the question, then, is this: there is a good method of finding the sun's distance, and there are indifferent methods; but since the good method has not been properly used, and since with all our skill we can only get indifferent results from the indifferent methods, it follows that we are not at present in possession of any very accurate knowledge of the distance of the sun from the earth.

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Hence it is that the coming transits of Venus on December 8th, 1874, and December 6th, 1882, are being looked forward to with great anxiety by all astronomers, to finally settle the question. Even now the plans are being discussed of the best methods to adopt. Every effort will be made to secure good stations for observing, good instruments, and good observers, and it is hoped by making good use of the experience of a century, the observations of 1874 and 1882 will show a great improvement on those of 1769.

It may be asked, why is it that astronomers are so anxious to know the distance of the sun? Why is it that they are prepared to undergo so much labour and undertake so much expense for such an object? The answer to such queries is the following:-When once the distance of the sun is known, we can find the size of the sun; we can find the distances of the planets, their sizes, and the distances of their satellites; and we can infer the relative weights of the materials of which they are composed: our knowledge of the distances of the stars, depends on the distance of the sun. In fact, it may be said that the distance from us of every heavenly body (the moon excepted) is known when we know the distance of the sun. Hence the value of the accurate knowledge which we expect to learn from the ensuing transits of Venus.

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languages, that she scarcely ever uses her own: she is conversant with nine languages. What a head she must have! Besides that, she knows every kind of fancy work under the sun. As for me, I don't know what my forte, or fortay, as Lydia would pronounce it, is-I don't think I have any. I can only sing little songs such as Edwin likes; and as for playing, I never could manage to make anything of the strange conglomeration of flats, and sharps, and naturals, that abound in the music Georgiana is so fond of. I like "Rousseau's Dream" and "The Last Rose of Summer," or "Home, Sweet Home" without variations; and as for languages, I am so content with my own, that I have quite forgotten all the others I learnt with my governess; and when we went to France last year, I offended a gentleman that mamma respected very highly. He spoke to me several times; I did not answer him. He thought I would not; the fact was, I could not. I hate the balls that the others are so fond of, and sit up half the night sometimes talking of whom they danced with, and what this gentleman said, and what that lady had on. I enjoy a picnic or a croquet party, and I am fond of going for long rambles after botanical subjects, and sketching all the pretty bits of scenery I see as I go along; but the worst of it is, I never finish my sketches. I don't dislike sketching, but I should never have the patience to niggle in a number of little strokes, as I see Sylvia doing sometimes; so that altogether there is not one study that I am clever at. I am also very short and smallscarcely more than half as tall as Sylvia, our beauty--and that is how it is I have been all my life called "Baby Jeanie;" and as I ever have been, I suppose I always shall be.

I fancy mamma was very much annoyed when I offended Monsieur le Comte last year, for she called me an ungrateful child, and said she did not know what would become of me. I may be mistaken, but I think she wished me to fall in love with him, or he to fall in love with me; though I am sure, for my part, I should never have done so, even if I had never seen Edwin.

I don't suppose I should ever have written all this, only that Edwin is going abroad, and he requested me to commence a diary, so that when he came back he might know all that had happened to me during the months he will be away.

August 20th.-It seems only natural that in this beautiful book-Edwin's last gift to me before he sailed the first entry should be about him. At mamma's last conversazione, while Georgiana was entrancing the select old fogies, the honour of whose acquaintance they are all so proud of, Edwin and I, finding ourselves what Lydia would express as decidedly de trop, managed to make

ourselves very happy in a little recess formed by the curtains of the bay window, a corner where we could sit quite unobserved, and enjoy our own exclusively select conversazione. I can scarcely tell how it came about, but when we left our nook, we were as certainly and solemnly engaged to each other as were ever man and woman, and matters had gone so far that it had become positively necessary to obtain papa's and mamma's consent. We parted with the mutual understanding that Edwin would call upon papa the next evening for that especial purpose. Somehow or another it had all happened so quietly, that no one seemed to have any notion of the important matter that was being discussed in the next room, nor, when I ran out of the drawing-room, glad to escape from the gossip and tattle that was going on, did I attract any more than ordinary atten. tion.

I was sitting by my bedside wondering when Edwin would come out, when a tap came at my door, and my maid Ruth entering, told me that papa wished to speak to me in the library. Without waiting a moment, I went down. Papa looked at me very kindly, and, putting his hand on my shoulder, said

"So, Miss Jeanie, I hear, upon very good authority, that you have gone and fallen in love. Silly little child! not long out of the school-room, eh?"

"Two years, papa," I said, a little indignantly; and scarcely knowing whether papa was vexed or pleased.

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And, now, I should like to know what is to be done?" papa continued, rather sternly, as I thought.

"I don't know, papa," I answered, feeling very near crying.

Papa must have guessed what a hard matter I had to keep from doing so, for he said, “There, there, it's all right, little body. Run along to Edwin, and he'll tell you of my stern decree, while I go and fetch mamma and let her into the secret."

Papa always spoke to me as if I were a child. It was very easy to guess what papa's answer had been, and now we only waited to hear that mamma agreed with him.

Presently they both came back together, and papa, in a joking manner, that I could not thoroughly appreciate just then, told mamma how affairs stood.

"Baby Jeanic!" said mamma; "she's such a child, she is not fit to be engaged, and much less to be married. She is such a wild thing, too."

I generally manage to think naughty things; but at that moment I could not help remembering how anxious mamma had seemed last year that I should receive the attentions of M. le Comte

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