PRACTICAL CONSTRUCTION.

4U6

1655. Putting the cost of a zinc roof with iron rafters anil curved flattenedsheet-zinc at £'25, 7s., the cost of a timber and slate roof would be £58, 17s. lid.Stating the cost of a zinc roof with iron rafters and corrugated zinc as in fig.885 at £4, 3s. Gd., the cost of the same extent of slate and timber would be £10.

DIVISION FOURTH—MISCELLANEOUS APPLIANCES.

Subdivision First — Fittings of the Workshop.

1656. Section First— Tools of the Joiner. —The distinction between the twooperations of Carpentry and Joinery may be simply stated. In carpentry, theframing and erecting of heavy timbers for the purposes of floors, roofs, partitions,&c., is the principal business; in joinery, the making and fitting up of externaland internal furnishings—as door-cases, doors, windows, window-frames, &c.—are the operations to be performed. In both, however, there are many commonoperations, which differ only in the fact that, for the purposes of joinery, theymay be on a smaller scale than when required for those of carpentry. Ingeneral, all timbers used for carpentry are left rough as they come from theoperation of the saw or the axe ; while in joinery, all exterior surfaces are nadesmooth and uniform by appropriate instruments. The tools required foi thesimple operations of joinery to be carried out on a farm-steading, may beenumerated as follows : the “ ripping-saw,” for cutting up heavy planks—theteeth in this are 96 to the foot, or 16 to the two inches; the “hand-saw,” forordinary work, 45 teeth to the foot; the “sash-saw,” for cutting fine vork,with a brass back—it has 156 teeth to the foot. For cutting dovetails, a smallsaw, having 180 teeth to the foot, is used. Tenons may be cut out by meansof the “ sash-saw.” A long, thin, and narrow saw, termed a “ key-hole siw,”having no back, aud useful for cutting out holes in wood : a size as follows willbe useful—length 12 inches, breadth at point ^ inch or j\ths, breadth at handle| inch. The planes used in joinery are very numerous. The “jack-plane” isused for taking the rough surface off the timber to be smoothed in surface. Itis used by taking off as much as can be taken in by one arm-stretch—the vork-man beginning at the near side of the plank, and gradually taking off the roughacross the breadth of the plank. On a part of the plank within arm-reacL be-ing done, the workman moves farther along, until the whole surface is ictedupon. To bring this surface properly smooth and to a level, a larger andheavier plane is used, termed the “trying-plane.” Shavings are taken off withthis the whole length of the plank. To test the level of the surface, a stra ght-edge (that is, a piece of wood about 18 inches long, inch thick, and 2 inchesbroad, having one edge perfectly true and square) is laid across the face, andthe workman looks along the plank, where the straight-edge is lying on it: allinequalities are then easily observed, and are to be reduced by the plane. Asthe edges of the plane are generally accurately cut, the workman sometmestests the “ truth ” of the surface of the work by laying the edge of the underside of the plane across the face of the plank. The “hand or smoothing phne ”is used for giving a final truth and smoothness to the work, and for finishing upsmall work. It is used with both hands in some operations—with only ore inothers. It is much shorter than the two others, being about 7 inches—thelength of jack-plane being 18, and that of the trying-plane 22 inches. For