by small cupolas from the rain. Sitting by the side of these, and peering down, I failed to see any gleam of water, and could catch no reflection from a lighted match. I heard a peculiar dull sound; thud, thud, thud, like the beating of some big engine, and I discovered from the flaring of the match that a steady current of air set down the shaft.
"Moreover, I carelessly threw a scrap of paper into the throat of the well, and instead of fluttering slowly down, it was at once sucked swiftly out of sight. After a time, too, I came to connect with these wells certain tall towers that stood here and there upon the hill slopes. Above these there was often apparent a peculiar flicker of the air, much as one sees it on a hot day above a sun-scorched beach.
"Putting these things together there certainly seemed to me a strong suggestion of an extensive system of subterraneous ventilation, though its
