Page images
PDF
EPUB

that I could improve upon this description.' The appearance here described will be recognised in Mr. Browning's drawing (Plate I.); it is also observable in figs. 49 and 50.

Other astronomers now joined in the discussion. Messrs. Stone and Dunkin, of Greenwich, asserted that with the fine equatorial of that observatory, luminous spots shaped like rice-grains could be seen, and that these spots, by overlapping, produce the dark

[merged small][graphic]

Illustrating the markings of the penumbræ of spots. (Capocci.)

pores. Fr. Secchi described the appearance of the luminous spots as resembling strokes made with a camel's-hair pencil. He described them, in fact, in terms closely according with those employed by Mr. Dawes. Dr. Huggins speaks of these luminous objects (or granules, as he calls them) as certainly not interlacing on the general surface of the photosphere. Fig. 51 represents a view of a portion of the Sun's disc as seen by him. It will be noticed that if this view is held at a considerable distance from the eye the

general aspect corresponds closely with the mottled appearance presented by the Sun in telescopes of moderate power.*

[merged small][graphic][subsumed]

A portion of the solar surface, showing granules. (Huggins.)

Other observers agree with Mr. Nasmyth, who adheres, I believe, to his original opinion. As regards

In drawing Plate II. with the low power and small aperture described at p. 215, I was struck with the perfect distinctness of this mottling all over the disc.

the assertion that Sir William Herschel had long since recognised these objects, it is of course to be rejected or accepted according as Mr. Nasmyth's opinion as to the real nature of the objects is confirmed or confuted. If there really is the interlacing he speaks of on the general surface of the Sun, then undoubtedly he is the discoverer of the phenomenon, for Sir William Herschel nowhere speaks of any such appearance (to my recollection, at least). Sir John Herschel, too, deals with Nasmyth's observation as undoubtedly new and also as of unmistakable interest and importance.

* Let me here quote Sir John Herschel's account of Nasmyth's willowleaf theory, partly on account of its liveliness and graphic clearness, partly for the sake of his reflections on the subject:- These leaves, or scales, are not arranged,' he says, 'in any order (as those of a butterfly's wings are), but lie crossing one another in all directions, like what are called spills in the game of spillikins; except at the borders of a spot, where they point for the most part inwards, towards the middle of the spot, presenting much the sort of appearance that the small leaves of some water-plants or sea-weeds do at the edge of a deep hole of clear water. The exceedingly definite shape of these objects; their exact similarity one to another; and the way in which they lie across and athwart each other (except where they form a sort of bridge across a spot, in which case they seem to affect a common direction, that, namely, of the bridge itself)—all these characters seem quite repugnant to the notion of their being of a vaporous, a cloudy, or a fluid nature. Nothing remains but to consider them as separate and independent sheets, flakes, or scales, having some sort of solidity. And these flakes, be they what they may, and whatever may be said about the dashing of meteoric stones into the Sun's atmosphere, etc., are evidently the immediate sources of the solar light and heat, by whatever mechanism or whatever processes they may be enabled to develope, and as it were elaborate, these elements from the bosom of the non-luminous fluid in which they appear to float. Looked at in this point of view, we cannot refuse to regard them as organisms of some peculiar and amazing kind; and though it would be too daring to speak of such organization as partaking of the nature of life, yet we do know that vital action is competent to develope at once heat, and light, and electricity. These wonderful objects have been

Before leaving the subject of the willow-leaves, I must quote one of the latest observations bearing on this subject. On April 13, 1869, Secchi noticed that over the whole of a large spot and its neighbourhood, there were multitudes of leaves, and that a bridge across the spot was formed of elongated leaves. The leaves in the neighbourhood of the spot were oval, the greater diameter about three times the less-thus, 'like the leaves of the olive and certain salices.' He says, What are these things? There are veils of the most

FIG. 52.

intricate structure. The spot has a third nucleus in which are the leaves seen in the drawing (fig. 52), all arranged in a radiating manner, precisely like a crystallization of sal-ammoniac seen by means of the solar microscope-attached to a stalk (lingua). It is clear that the rest of the nucleus is due to the rarefaction of

seen by others as well as by Mr. Nasmyth, so that there is no room to doubt of their reality. To be seen at all, however, even with the highest magnifying powers our telescopes will bear when applied to the Sun, they can hardly be less than a thousand miles in length, and two or three hundred in breadth.' So that if these things are solar inhabitants whose fiery constitution enables them to illuminate, warm, and electricise the whole solar system, they are not wanting in that evidence of might which gigantic size affords. Truly, Milton's picture of him who on the fires of Hell lay floating many a rcod,' seems tame and commonplace compared with Herschel's conception of these floating monsters, the least covering a greater space than the British Islands.

[ocr errors]

Q

such leaves. There cannot be a shadow of a doubt on this matter.'

On April 14, the spot in which Secchi had observed these singular objects presented the appearance depicted in fig. 53. It was in a marvellous condition,'

[merged small][graphic][merged small]
[ocr errors]

says Secchi, full of bridges, arcs, stalks, and leaves, like the great spot of 1866.'*

* Memoria III. sugli spettri prismatici de' corpi celesti. Secchi assigns the following dimensions to this remarkable group :

Total diameter in length

[blocks in formation]

Diameter of the two principal nuclei

Breadth of the spot

Breadth of the nucleus

Breadth of the bridge

[blocks in formation]
« PreviousContinue »