The following observations, while bearing more or less on casting generally, refer more particularly to the art of the ironfounder.

The first consideration is the pattern from which the moulding is to be made, the planning of which necessitates a knowledge of shrinkage and cooling strains in heated metal. Founding operations are divided into 2 classes, known technically as green sand moulding and loam or dry sand moulding: the first, when patterns or duplicates are used to form the moulds; the second, when the moulds are built by hand without the aid of complete patterns. Founding involves a knowledge of mixing and melting metals such as are used in machine construction, the preparing and setting of cores for the internal displacement of the metal, cooling and shrinking strains, chills, and many other things that are more or less special, and can only be learned and understood from actual observation and practice.