[Illustration: Furnace Iron. Brush. Trowel. Bellows. Foot Rule. Level. Shovel. Spatera. Hammer. Mould Weight. Rammer.] We have only described solid castings, but as ornamental iron work is generally made hollow, this has to be cast in rather a different way, though the only difference is that what are called “cores” are used. These cores are in fact solid metal patterns made a little smaller than the hollow left by the real pattern, and allowed to remain in the mould. The melted iron then flows between the surface of the core and the surface of the mould, and the casting is hollow, so that when the core is removed the metal is only the thickness of the space left between the two surfaces. You will see what is meant by placing a small teacup inside a larger one, and then pouring water between them. The tools used by the Ironfounder are not very numerous: the casting ladles and mould have already been mentioned; the uses of the _shovel_ and the _mould weight_, the _rammer_, and the _furnace iron_ need no description. The designers, and pattern makers, and the mould maker have the most important duties, and the latter will have to use a small _trowel_ and a _spatera_ for arranging his sand and loam, a _level_ that it may be perfectly true, and a _brush_ and a _pair of bellows_ for removing any particles of grit from the surface of the channels where the pattern has been impressed. Almost all irons are improved by admixture with others, and, therefore, when superior castings are required they should not be run direct from the smelting furnace, but the metal should be remelted in a cupola furnace, which gives the opportunity of suiting the quality of the iron to its intended use. Thus, for delicate ornamental work, a soft and very fluid iron will be required, whilst for girders and castings exposed to cross strain the metal will require to be harder and more tenacious. For bed-plates and castings which have merely to sustain a compressing force, the chief point to be attended to is the hardness of the metal. Castings should be allowed to remain in the sand until cool, as the quality of the metal is greatly injured by the rapid and irregular cooling which takes place from exposure to air if removed from the moulds in a red hot state, which is sometimes done in small foundries to economise room. [Illustration] THE BLACKSMITH. [Illustration: FORGE.] In the building and fitting of the house a large portion of the iron work will have to be furnished by the Smith, and as we have already given some description of iron founding, it will be necessary to say something about the Blacksmith, or the worker in iron or black metal, whose business is different from that of the whitesmith, which has to do more particularly with white or yellow metal.