The Penaebach tunnel is the only one in England that is self-supporting. It is driven through solid basalt. The Penmaenwhr tunnel, pierced through hard green-stone, had to be lined throughout; and the Bangor tunnel, supposed to be sufficiently firm, was afterward cased with brick. It has been found necessary to line some of the tunnels of the Washington aqueduct, which are driven through very hard gneiss. Before taking leave of this instructive report, we have selected some interesting portions of the narrative and scientific statements for quotation: “The great falls of the Hingador are grand and exceedingly romantic, and equal in height and beauty to many of those in other countries which elicit so much admiration from all lovers of magnificent scenery. The valley itself is pleasant to gaze upon; many bright streams gush into it, and impart additional charms to the already picturesque landscape of falls and rapids, and rich tropical vegetation. Several thermal springs were discovered at the foot of the great falls. “As the party had to wade through the water, over smooth and slippery rocks, and clamber up steep precipices, it took four days to accomplish this section of the survey. Several fragments of rocks were broken off at the head of the falls for subsequent analysis. According to the report of the geologist, of which the following is an extract, ‘the rocky falls were found to be overcoated with a light, shaly conglomerate of a cemented texture, and containing, imbedded in a calcareous matrix, coarse sand and gravel. Higher up, in one of the western head branches of this stream, a more consolidated semi-rock was noticed, containing copiously interspersed fragments of little shells. This rock seems also to be impregnated with carbonate of lime.’”