'Annual Variations in the Apparent Movement of the Spots', c 1875.
© Science Museum / Science & Society Picture Library
Plate taken from 'Le Soleil' (Paris, 1875) by Angelo Secchi, showing the annual movement of sunspots. 'The trajectories described by the spots vary with the season: [For instance,] in March (sphere B) they are very elongated ellipses turning their convexity to the north, the great axis of the ellipse being almost parallel to the ecliptic.' The curves and the inclinations in this figure have been slightly exaggerated, in order to make the variations better understood.