This is very easy, as, while the wood is green, it is so soft that a blow from a “machete,” or native cutlass, is sufficient to separate it. With the same instrument the native makes these flat planks into paddles for his canoe, the soft wood yielding readily even to the imperfect edge of the rude tool. When the wood dries, it becomes very hard, light, and singularly elastic, all these properties qualifying it for its object. I have several of these paddles in my collection. They are much prized by the natives, and are always stained in various patterns with red and black dyes. In consequence of the use which is made of this tree, it goes by the popular name of “paddle-wood.” THE TUNNEL USED AS A PASSAGE. As to this division of the subject, I have not been quite sure where it should be placed, but think the present position a tolerably appropriate one. We have already, in the igloo of the Esquimaux and the winter dwelling of the seal, found examples of the Tunnel when used as an appendage to the houses and a means of security. We now come to the Tunnel as affording the means of locomotion. [Illustration: TUNNEL OF ANOMMA. PHOLAS. SHIP-WORM.] [Illustration: RAILWAY TUNNEL.] Take, for example, our own railway system. Had it not been for the power of tunnelling, the railway would have lost nearly its whole value, for it would have been restricted to local districts, and could not have penetrated, as it now does, to all parts of the country, without reference to hill, dale, or level ground. Our present system of engineering has wonderfully developed the capability of tunnelling. In former times it was thought a most wonderful feat to drive a tunnel under the Thames, while in these days the tunnel through Mont Cenis has been completed, and we are hoping to make a submarine tunnel from England to France. * * * * * IN Nature we can find many examples of Tunnels used for similar purposes. The silken tunnel of the Wax-moth larva has already been mentioned, and we now come to Tunnels where earth in some form, and not silk, is the material of which they are constructed. The lowermost figure on the left-hand side of the illustration represents that well-known and most destructive burrower, the Ship-worm (_Teredo_), which, by the way, in spite of its popular name, is not a worm, but a mollusc. This creature has a peculiar interest for engineering, inasmuch as its mode of working gave Brunel the first idea of subaquatic tunnelling in loose, sandy soil, just as the Victoria Regia leaf gave to Paxton the idea which afterwards developed into the Crystal Palace.