There is something curiously arresting in this quick passage from a green glade carpeted with flowers to the calcined ash and the grey desolation of this broken hillside. Of vegetation there is almost none, except a stunted heather which creeps hardily towards the blast hole. A little way off, towards the right, lies a level space sunk beneath the surrounding land, not unlike the fashion of an asphalt skating rink, so even in its surface that it resembles the work of man, and one strolls towards it to discover with what purpose anyone had dared to tamper with the soil in a spot where so thin a crust lies over bottomless pits of fire. But when one steps out upon the level flat, it reveals itself at once to be no human work. The guide stamps with his foot, and remarks that the sound is hollow. It is indeed, most unpleasantly so. He jumps upon it, and the surface quivers. You beg him to spare you further demonstrations, and walking gingerly on tiptoe, wishing at each step that you were safe in Regent Street once more, you follow him out towards the middle of this devilish crust, which rocks so easily and covers something which you hope devoutly you may never see. Midway in the expanse the fellow pauses in triumph--he has reached what he is confident will please you. He is standing by a hole, just such an opening as is made in a frozen lake in winter for the watering of animals. From it there emerges a little vapour and a curious low sound, like that which a child will make with pouting lips. The guide grins, crouching by the opening; you, on the other hand, hang back, in doubt whether the crust may not break off and suddenly enlarge the hole. You are encouraged forwards, and at last, peering nervously down the hole, you see with keen and lively interest that the crust appeared to have about the thickness of your walking-stick, at which depth there is a lake of boiling mud. The grey mud stirs and seethes in the round vent-hole, rising and falling, while on its surface the gas collects slowly into a huge bubble, which forms and bursts and then collects again. For my part I do not deny that the sight fascinated me, but it deprived me of all wish to tread further on that shaking crust, and I sped back as lightly as I might, wishing all the way for wings, to where there was at least sound, green earth for a footing, in place of pumice stone and hardened mud, which some day, surely, will fly into splinters, and leave the seething, steaming lake once more open to the heavens. [Illustration: POZZUOLI]