At a quarter past four they sighted the sea, and here, the air beginning to grow chill, the balloon dropped earthward, and for some miles they skimmed the ground, disturbing the partridges, scattering the rooks, and keeping up a running conversation the while with labourers and passers below. In this there was exercise of perfectly proper aerial seamanship, such as moreover presently led to an exhibition of true science. To save ballast is, with a balloon, to prolong life, and this may often best be done by flying low, which doubtless was Green's present intention. But soon his trained eye saw that the ground current which now carried them was leading them astray. They were trending to the northward, and so far out of their course that they would soon make the North Foreland, and so be carried out over the North Sea far from their desired direction. Thereupon Green attempted to put in practice his theory, already spoken of, of steering by upper currents, and the event proved his judgment peculiarly correct. "Nothing," wrote Mr. Monck Mason, "could exceed the beauty of the manoeuvre, to which the balloon at once responded, regaining her due course, and, in a matter of a few minutes only, bearing the voyagers almost vertically over the castle of Dover in the exact line for crossing the straits between that town and Calais." So far all was well, and success had been extraordinary; but from this moment they became faced with new conditions, and with the grave trouble of uncertainty. Light was failing, the sea was before them, and--what else thenceforth? 4.48 p.m. was recorded as the moment when the first line of breaking waves was seen directly below them, and then the English coast line began rapidly to fade out from their view. But, ahead, the obscurity was yet more intense, for clouds, banked up like a solid wall, crowned along its frowning heights, with "parapets and turrets and batteries and bastions," and, plunging into this opposing barrier, they were quickly buried in blackness, losing at the same time over the sea all sound from earth soever. So for a short hour's space, when the sound of waves once again broke in upon them, and immediately afterwards emerging from the dense cloud (a sea-fog merely) they found themselves immediately over the brilliantly lighted town of Calais. Seeing this, the travellers attempted to signal by igniting and lowering a Bengal Light, which was directly followed by the beating of drums from below.