It is easy to understand whence this earthy matter (twenty or thirty per cent) comes. Throughout the neighborhood the ground is full, to the depth of hundreds of feet, of coaly and asphaltic matter. Layers of sandstone or of shale containing this decayed vegetable alternate with layers which contain none; and if, as seems probable, the coaly matter is continually changing into asphalt and oil, and then working its way upward through every crack and pore, to escape from the enormous pressure of the superincumbent soil, it must needs carry up with it innumerable particles of the soils through which it passes. In five minutes we had seen, handled, and smelt enough to satisfy us with this very odd and very nasty vagary of tropic nature; and as we did not wish to become faint and ill between the sulphureted hydrogen and the blaze of the sun reflected off the hot black pitch, we hurried on over the water-furrows, and through the sedge-beds to the farther shore--to find ourselves, in a single step, out of an Inferno into a Paradise. [Illustration] A STALAGMITE CAVE (FROM THE VOYAGE OF THE CHALLENGER.) BY SIR C. WYVILLE THOMSON, KT., LL.D., ETC. [Illustration] I think the Painter's Vale cave is the prettiest of the whole. The opening is not very large. It is an arch over a great mass of débris forming a steep slope into the cave, as if part of the roof of the vault had suddenly fallen in. At the foot of the bank of débris one can barely see in the dim light the deep clear water lying perfectly still and reflecting the roof and margin like a mirror. We clambered down the slope, and as the eye became more accustomed to the obscurity the lake stretched further back. There was a crazy little punt moored to the shore, and after lighting candles Captain Nares rowed the Governor back into the darkness, the candles throwing a dim light for a time--while the voices became more hollow and distant--upon the surface of the water and the vault of stalactite, and finally passing back as mere specks into the silence. [Illustration: A GUIDE.]