“I cannot grasp it!” said Lees Ingle, an electrician. “I cannot comprehend how you can overcome gravity in this way, and why we are not overwhelmed! but then, that’s your affair!” and he laughed, thoroughly mystified. “There’s this in it, anyway!” observed Godfrey, also laughing, “they’d scarcely come and bring _me_ if there was much danger of being frizzled, and if we get toasted they do, for we’re all in the same boat.” This safe passage of the tidal-wave set all doubts at rest finally, which was felt by all a wonderful relief, and with added zest they set to work again, this time to investigate the sun spots, but they could not find any. For days they wandered to and fro, seeing only larger and smaller ‘granules’ and ‘pores,’ as the heat and movement were more or less intense; but owing to the difficulty of seeing far ahead by reason of the heavy and fiery clouds above, and the deceptive whiteness of the surface below, they were unable to locate their position, for terrestrial compasses were useless. At last, after a long search they came to a zone of what they judged to be the familiar ‘sun spots’ which may be seen from Earth any day without the aid of a telescope, if there be but a little fog, or a smoked glass handy, and straightway commenced examining, measuring, and observing the origin of their formation, and why Earth was affected by their movements. The primary cause was found to be the enormous pressures of vapour and currents of heat, which, acting violently on certain parts of the photosphere, made those parts much fiercer and brighter by the intensity of the heat, and thus the parts adjacent and surrounding the whiter portions appeared considerably darker by contrast, just as a spot of brilliant white placed on a piece of paper less white will cause that portion of the paper immediately surrounding it to appear grey by contrast. Such portions resumed their normal state when the fierce local heat had passed—or, in reality, when the super-heated portion had cooled to that of the surrounding portions and the colour had become normal and even; for in these cases there are no spots except by contrast, which accounted satisfactorily for the fact that from Earth dark spots are seen to remain for various lengths of time, from a few minutes to a few days, and then vanish, suddenly to appear again elsewhere, following the course of the super-heated zone or the locality which might then be in a state of constant motion.