By means of these branches of handicraft much of our most intricate work is now performed in a comparatively simple manner. They imply the making of a mould or cavity of the desired shape in some suitable substance by means of a model or pattern, and the filling of this mould with liquid metal, which, when cold, will be of the desired form. There are three common kinds of moulding, green sand, dry sand, and loam. The first is the class of moulding in most general use, an explanation of which will be sufficient for our present purpose. The moulds are made in fine river sand mixed with old foundry stock, and in positions of close proximity to the pattern, with coal dust in the case of such metals as cast-iron, requiring a high temperature to melt them. The addition of the coal dust is to prevent the melting of the sand as far as possible, and increase the porosity of the mould. Moulds are in most instances made from patterns constructed of wood, which are formed so as to be readily extracted from the sand. An allowance of about 1/10 in. per foot has to be made for the contraction of the metal in cooling, and the same amount, and often more, is given as draw or taper, so as to enable the patterns to be removed from the sand without damage. All patterns have, therefore, to be made so much larger than the castings required, for which cause a special contraction rule has to be worked from. Many castings are made from metal patterns, so that, in the construction of the original, double contraction must be allowed.

When the moulder has been provided with a pattern from which one or more castings may be required, and after he has been satisfied that it is properly put together, he selects suitable boxes, usually made of cast-iron and supplied with numerous cross bars, in which the sand forming the mould is held firmly together. Foundries have a large number of such boxes, generally made in pairs - the bottom one being known as the drag, and the top one as the cope. The sand is then sifted, mixed, and made moist enough for adhesion and taking the correct impression. If the pattern is small and of such a shape that it may be completely imbedded in the sand of the drag, then it should be laid face down on a flat board and the drag placed over it in an inverted position. The facing sand, containing the coal dust, may now be put carefully over the pattern through the bars of the drag to the depth of an inch and half or thereby and carefully rammed, more common foundry stock being added as the ramming proceeds until the box is filled flush, when the surplus should be cleaned off and the box restored to its original position. Equality in ramming is very desirable, and both extremes should be avoided. If too slack the mould will not be strong enough, but if the other extreme be the condition of the sand, the easy escape of the gases will be prevented and possible damage to the casting may ensue. A little dry sand, or brick dust, should now be shaken over the face of the drag to act as parting sand, and ensure an easy separation of cope and drag. The cope is now placed in its proper position, exact replacement being ensured by the use of guide pins, and a round pin, to form the ingate or entrance for the metal through the sand of the cope, is then fixed in the most suitable place. The cope may next be filled up in the same manner as the drag, and when finished the sand should be sufficiently pierced towards the mould with a sharp wire to make sure of good ventilation. In no case should the piercing point be allowed to come in contact with the pattern. Rapping on the outside of the boxes is necessary in all cases when part of the pattern is contained in the sand of the cope so as to slacken it, after which the top box may be removed. The upper box must be raised simultaneously at all points, and unless this is done, the mould will often suffer. The pattern may now be extracted from the sand of the drag. Occasionally the rapping outside the boxes will be all that is needed for the removal of the pattern, but in cases when the parts are deeply imbedded in the sand, a repetition of the process may be necessary when the upper box has been removed. The pattern should not be struck directly (if it can be avoided), but on a rapping-rod, often supplied for the purpose, which may also be used for lifting the pattern from the sand. The ingate pin should now be removed and an opening made into the mould. All damage done to the sand in both boxes should now be repaired, and the surfaces of the mould sleeked over with plumbago by the use of suitable trowels. The last-mentioned part of the work gives a better skin to the mould and makes the sand more easily removed from the casting. If small parts are found broken, the fractures may be repaired by the use of clay-water, while nails are often brought into requisition to give extra strength. The cope should now be cautiously replaced, after which the mould is ready for the metal. In many instances it will be necessary to place weights upon the top box to prevent its being raised by the molten metal. It is also a wise precaution to place something in the mouth of the ingate to prevent anything falling down before the metal has been poured. Should a casting be required hollow, clay cores are used to give the desired internal form. These cores are made in specially formed boxes, which, in some instances, are more difficult to construct than the patterns themselves. After removal from the core boxes, they are placed in an oven and thoroughly dried. In such castings as long water pipes, columns and similar articles, where the core might bend, small supports called chaplets are used. The stem is made of wrought-iron, about 1/4 in. square, having on one end a piece of hoop iron of suitable shape and size. Sufficient support for the sand is not, at all times, obtained from the cross bars of the cope, particularly in large flat castings. Iron hooks, or hangers are very extensively employed as auxiliaries.