openings, and particularly small ones, have no shallows whatever.

Openings have sometimes a difference of colour, apparently because a thin veil of luminous clouds is hovering over them.

Openings, which are always temporary, divide when decaying, and sometimes increase after diminishing; but, in general, after dividing, they diminish and finally disappear, leaving the part of the sun's surface upon which they have been seen, more than usually disturbed.

Fig. 3 represents an opening with a branch from its shallow. That opening, in the course

Fig 3

Fig. 5.

Fig

4

of an hour after it had assumed the appearance

How do the appearances of openings generally terminate? What were some of the successive appearances of the opening shown in Fig. 3?

which is here given to it, exchanged it for another, as you see in Fig. 4.

Fig. 5 is another opening, with a long shallow. In three hours it had assumed the appearance of Fig. 6; and in an hour after this, an

Fig. 6.

Fig. 7.

Fig. 8.

Fig. 9.

opening appeared in the shallow, as in Fig. 7. The openings are generally at their greatest extent, as in Fig. 8, when the shallows begin to diminish, and the lips, or projections, to disappear. The division of the decaying opening is shown in Fig. 9; where the luminous passage across the opening resembles a bridge thrown

over a cave.

When have the openings

What, in the opening, Fig. 5? generally arrived at their greatest extent? of a decaying opening?

What of the division

Sir William Herschel imagines that the openings are occasioned by an elastic but not luminous gas, which issues through minute and commencing openings, or pores, and which, forcing its way through them, spreads itself on the luminous clouds, drives them out of its way and thus widens the passage, or enlarges the opening. But the direction of the stream of gas is often oblique or slanting; and thus the luminous clouds are drawn laterally or sidewise, and form a larger shallow upon one side than upon the other.

What did Sir William Herschel imagine of the cause of the openings, or black spots?

CHAP. XVI.

MORE ABOUT THE TELESCOPIC APPEARANCES OF THE SUN'S SURFACE. ABOUT THE MOVEMENTS, ALSO, OF THE SAME SURFACE.

FIG. 10 shows two branches of a shallow proceeding from a dark opening at the bottom of the figure. In the course of half-an-hour, one of the branches had united itself to the other, as in Fig. 11, and seemed to advance towards the opening D, while the other took the direction

came pointed, as in Fig. 12; and in the course of an hour it became broad at the point, and a new branch broke out, as in Fig. 13.

The new branch afterwards began to increase; and another branch, marked н in Fig. 11, began to break out from the shallow about E; and three small branches were seen to project from the shallow of the large opening in Fig. 14. The vacancies between those branches were afterwards filled up, from the same cause which occasioned their projection, so as to increase the breadth of the shallow upon that side of the opening.

Fig. 14.

Indentations are the dark parts of corrugations or wrinkles; and from the circumstance of their being visible very near the edge or limb of the sun, it seems that they are not much depressed below the level of the luminous clouds. The sides of the indentations (see Fig. 15) are like