doubly pleasing when we consider how much distressing toil has been alleviated by the employment of the man-engine. Machinery constructed on the same principle has been latterly adopted in the mines of Anzin, for transporting the coal step by step to the surface; and it is evident that when coal mines are worked at greater depths than at present, ropes, however strong, will no longer be able to sustain even their own weight, and the whole transport up and down a shaft of perhaps 3,000 or 3,500 feet must be performed by means of similar machines. [Illustration: TIMBERING OF A MINE.] Wherever the excavated rock is not hard or solid enough to bear the superincumbent weight, the galleries of a mine must necessarily be supported by timbering or walling. Timbering is most used, frequently in the form represented in the annexed woodcut; and when we consider how miles upon miles of galleries are thus supported, we can easily imagine that whole forests must be engulfed in our mines. It has been calculated that for the total quantity of timber in use for mining purposes in Cornwall, it would require no less than 140 square miles of forest of Norwegian pine, averaging a growth of 120 years. The expense thus incurred is enormous; the cost for timber, duty free, in Cornish and Devon mines, amounted in 1836 to 94,138_l._ and is probably still larger at the present time. For timbering, no tree is more esteemed than the larch or the Norwegian pine, on account of its great durability in the wet; but whatever wood may be employed, it is necessary to peel off the bark, experience having shown that unless this is done the wood rots much more easily, as the fibres of the rind attract a far greater quantity of moisture than the smooth surface of the splint. Like the potato and the grape, subterranean timbering is exposed to the attacks of a fungus, producing what is called dry-rot. The parasite germinates in the sap which remains in the wood, or at least derives its nourishment from it. Its vegetation is at first scarcely perceptible; but soon its white fibres multiply, and form at length small sponges on the surface. The decomposition of the wood now advances with rapid strides, and terminates at last in the total destruction of the ligneous fibres. Not satisfied with depriving the roof of its support, the dry- rot likewise produces a vitiation of the air, so that wherever timbering is employed, it is reckoned among the great enemies of the mine and of the miner. Many remedies have been recommended, among which _kyanizing_, or saturating the wood with a solution of corrosive sublimate, is one of the most efficacious, though unfortunately too expensive to be of universal use. Mushrooms of various kinds likewise flourish upon the moist surface of the spars, and various insects collect near this parasitic vegetation. [Illustration: TRANSVERSE SECTIONS OF WALLED DRAIN GALLERIES.]