No chapters in _Les Abîmes_ are more absorbing than those describing the exploration of underground waters. By means of collapsible boats, M. Martel explored the concealed streams that tumble into the canyon of the Ardèche. In 1890-91, M. Mazauric, with enormous toil and considerable danger, traced out the labyrinthine ramifications of the Bonheur at Bramabiau (Gard). The Tindoul de la Vayssière (Aveyron), with its yawning abyss and powerful subterranean torrent, and the Causse de Gramat (Padirac), both entailed the descent of a deep chasm and the navigation of large streams. At Padirac the exploring party made their way in four boats along a river, with frequent portages caused by dykes of stalagmite, and discovered some of the most exquisite and romantic stalactite scenery in the vaults through which the river flows. As a sport, cave exploring ranks high. The exertion it entails is exceedingly severe. The innumerable obstacles and difficult problems to be faced make incessant demands on our inventiveness, adaptability, and presence of mind. The exposure, the hardships, the dangers that must be encountered, form an admirable discipline. Those who consider these any detraction from the merits of the sport, must condemn, not one sport, but a whole class. Running risks, we must remember, is always foolhardy, but to nullify danger by means of science and skill is an aim worthy of the noblest kinds of sport. It will, of course, be objected that the lack of exhilarating conditions, and of the stimulus of fresh air, deprives the sport of the usual benefits of outdoor games. But the air at the bottom of a cave 100 or more feet deep is usually as pure and sweet, and not seldom as dry, owing to its free circulation, as that on the hills. Then the darkness and the sense of imprisonment, you say, are not conducive to healthy enjoyment. But a cave explorer, enthralled by the manifold interest and excitement of the pastime, will never admit this. The variety of entertainment it affords constitutes a peculiar charm.