_Rough casting_ is used for outside walls, and is done by throwing a layer of gravel, mixed with lime and water, over the second coat of plaster while it is quite wet. In some counties of England, and especially near Nottingham, the plasterers use reeds instead of laths; and even floors are often made by laying down a quantity of coarse stuff upon a foundation of reeds. These floors are almost as hard as stone, and possess the good quality of being almost always fireproof. [Illustration] THE CARPENTER. [Illustration: THE CARPENTER’S SHOP.] An account of the tools and implements used for working in wood would scarcely be complete without some remarks upon wood itself, and you can have no better information on this subject than that which has been written by a gentleman[1] who is thoroughly acquainted with the different kinds of timber, and with all the materials used in building. [1] Mr. E. DOBSON, Assoc. Inst. C. E. If we examine a transverse section of the stem of a tree, we perceive it to consist of three distinct parts; the _bark_, the _wood_, and the _pith_. The wood appears disposed in rings round the pith, the outer rings being softer, and containing more sap, than those immediately round the pith, which form what is called the _heart-wood_. These rings are also traversed by rays extending from the centre of the stem to the bark, called _medullary rays_. The whole structure of a tree consists of minute vessels and cells, the former conveying the sap through the wood in its ascent, and through the bark to the leaves in its descent; and the latter performing the functions of secretion and nutrition during the life of the tree. The solid parts of a tree consist almost entirely of the fibrous parts composing the sides of the vessels and cells. By numerous experiments it has been ascertained that the sap begins to ascend in the spring of the year, through the minute vessels in the wood, and descends through the bark to the leaves, and, after passing through them, is deposited in an altered state between the bark and the last year’s wood, forming a new layer of bark and sap-wood, the old bark being pushed forward. As the annual layers increase in number, the sap-wood ceases to perform its original functions; the fluid parts are evaporated or absorbed by the new wood, and, the sides of the vessels being pressed together by the growth of the latter, the sap-wood becomes heart-wood or perfect wood, and until this change takes place it is unfit for the purposes of the builder.