The area of this hydro-thermal district, which Mr. Percy Smith, the best living authority on the subject, calls the Taupo volcanic zone, is roundly about six thousand square miles. As already said, part of it lies under the sea, above which only White Island, Mayor Island, and Whale Island rise to view. Its shape, if we could see the whole of it, would probably be a narrow oval, like an old-fashioned silver hand-mirror with a slender handle. In the handle two active volcanoes lift their heads--Ruapehu, and Tongariro with its three cones. At the other end of the mirror White Island stands up, incessantly at work. This exhausts the list of active volcanoes; but there are six or seven extinct or quiescent volcanoes of first-class importance. Mayor Island, in the Bay of Plenty, is a dead crater rimmed by walls five miles round and nearly 1300 feet high, enclosing a terrible chasm lined with dark obsidian. Mount Edgecombe, an admirably regular cone, easily seen from the coast, has two craters in its summit; and the most appalling explosion ever known in the country occurred in the tract covered by Mount Tarawera and the Roto-mahana Lake. How terrific were the forces displayed by these extinct volcanoes in ages past may be judged by the vast extent of country overlaid by the pumice and volcanic clay belched forth from their craters. Not only is the volcanic zone generally overspread with this, only sparse patches escaping, but pumice is found outside its limits. Within these, it is, loosely speaking, pumice, pumice everywhere, dry, gritty, and useless,--a thin scattering of pumice on the hill-tops and steep slopes,--deep strata of pumice where it has been washed down into valleys and river terraces. Mingled with good soil it is mischievous, though two or three grasses, notably that called Chewing’s fescue, grow well in the mixture. Unmixed pumice is porous and barren. Fortunately the tracts of deep pumice are limited. They soak up the ample rainfall; grass grows, but soon withers; in dry weather a sharp tug will drag a tussock from the roots in the loose, thirsty soil. The popular belief is that it only needs a long-continued process of stamping and rolling to make these pumice expanses hold water and become fertile. Those who think thus point out that around certain lonely lagoons, where wild horses and cattle have been wont to camp and roll, rich green patches of grass are found. Less hopeful observers hold that the destiny of the pumice country is probably to grow trees, fruit-bearing and other, whose deep roots will reach far down to the water. Already the Government, acting on this belief, has taken the work of tree-planting in hand, and millions of young saplings are to be found in the Waiotapu valley and elsewhere in the pumice land. Prison-labour is used for the purpose; and though a camp of convicts, with movable prison-vans like the cages of a travelling menagerie, seems a strange