All the available evidence which we possess may be said to show that the spots are not merely superficial appearances, but that they have their origin deep in the interior of the Sun, and are produced by the operation of causes still unknown to us which affect and disturb the Sun’s mass to an extent which is sometimes very considerable. The spots then are only the results of a great agitation in the materials of which the Sun is composed, and this agitation extends far down below the limits of the visible dark nucleus whatever that may consist of. Besides the spots, streaks of light may frequently be remarked upon the surface of the Sun towards the margin of the disc. These are termed _faculæ_ (torches), and they are often found near the spots, or where spots have previously existed or have afterwards appeared. When quite near the Sun’s limb these faculæ are usually more or less parallel to the limb. They are of irregular form and may be likened to certain kinds of coral. They generally appear to be more luminous than the solar surface immediately adjacent to them, but it is not improbable that this is an optical illusion depending upon the fact that the edges of the Sun always appear much more luminous than the centre. This last-named fact may be readily recognised by the employment of a high magnifying power, and moving the telescope rapidly from the limb to the centre of the disc. If the Sun be projected on a screen, as already mentioned, this degradation of the Sun’s light from centre to circumference becomes particularly manifest. After having studied the structure and the movement of the spots, one is naturally led to ask if their apparitions at different periods are subject to any general law. This question is one which has much engaged the attention of modern astronomers. The older observers noticed that the number of the spots visible differed in different years. There were said to have been periods when months and even years passed away without any spots being observed. Even allowing that this statement, so far as “years” are concerned, might be exaggerated, and that the absence of spots was due to the want of sufficient care in making the observations, and especially to the want of efficient instruments, it is none the less true that the number of the spots is extremely variable, and that there have been epochs when they were very scarce. Sir W. Herschel was the first who devoted himself to the question of seeking to establish a relation between the variation of the spots and terrestrial meteorology. For the want of any better object, he compared the annual number of the spots with the price of wheat; but it is easy to see that nothing could result from such a comparison. Without doubt the meteorological phenomena of the globe must depend to some extent on solar changes: but the term of comparison selected by Herschel had no direct bearing on the state of the Sun.