The apparent movements of the spots vary also from month to month during the year according to the season. In March their paths are very elongated ellipses with the convexity towards the N., the longer axis of the ellipse being almost parallel to the ecliptic. After that epoch the curvature of the ellipse diminishes gradually, at the same time that the major axis becomes inclined to the ecliptic, so that by June the flattening of the ellipse has proceeded so far that the path has become a straight line. Between June and September the elliptical form reappears but in a reversed position; then, following these reversed phases, the ellipticity decreases, and for the second time there is an epoch of straight lines. This happens in December, but the straight lines are inclined in a converse direction to that which was the case in June. It must again be impressed on the reader that all these seemingly different forms of path pursued by the spots are merely effects of perspective, for in reality, the spots in crossing the Sun’s disc describe lines which are virtually parallel to the solar equator. These projections really depend of course on the position of the observer on the Earth, and vary as his position varies during the Earth’s annual circuit round the Sun. The number of the spots varies through wide limits. Sometimes they are so numerous that a single observation will enable us to recognise the position of the zones of maximum frequency. Sometimes, on the other hand, they are so scarce, that many weeks may pass away without hardly one being seen. A remarkable regularity is now recognised in the succession of these periods of abundance and scarcity, as we shall see later on. It is both useful and interesting in studying the spots to record methodically their number and their size, but it is not easy to teach observers how to do this so systematically that observations by one person can be brought into comparison with those of another. Photography and hand-drawing on a screen alone furnish a trustworthy basis of operations. Spots in general may naturally be classified into (1) isolated spots or points, and (2) groups of spots; but often one observer will describe as a small spot an object which another observer would regard as a mere point; and one observer will record several groups where another observer will see but one. A very few days’ experience with a telescope will bring home to the observer’s mind the difficulty of dealing with the spots where it is a question of systematic methodical observation of them.