The process of casting a bell, as employed both by ancient and modern founders, may be described somewhat as follows:--The first business is the construction of the core, a hollow cone of brick somewhat smaller than the inner diameter of the intended bell, over which is plastered a specially-prepared mixture of clay, bringing it up to the exact size and shape of the interior of the bell. This was usually modelled with the aid of a wooden “crook,” something like a pair of compasses; but is now done with an iron framework called a “sweep,” which revolves on a pivot and moulds the core by means of metal blades. This clay mould is then baked hard by means of a fire lighted within it. The next stage was the construction of the cope or outer casing of the mould, which used to be also made in hard clay, its inner surface following the _outer_ shape and dimensions of the bell. The “thickness” of the bell itself, i.e., the part to be occupied by the molten metal, was formed in a friable composition which was laid over the core and then destroyed. In modern times the “thickness” has been dispensed with, the cope being formed by lining a casing of cast iron with clay shaped to the external form and dimensions of the bell. The mould is now complete, except for providing for the cannons or metal loops which attach the bell to the stock, and the loop to which the clapper is suspended inside. Every care having been taken to adjust the respective positions of the cope and core with exactness, the molten metal is then poured in through an opening, and left to cool, after which the bell comes out complete. The process is analogous to that known as _cire perdu_, employed by sculptors for the casting of bronze statues. Illustrations of the moulding processes are given in Plates 6-10.
Inscriptions and ornaments are produced in relief on the bell from stamps, also in relief, which are pressed into the mould, making a hollow impression in it. Copies of coins were often produced in this way by the older founders. Down to about the end of the seventeenth century each letter, or sometimes each word, was placed on a separate _patera_ or tablet of metal. The usual place for the inscription is just below the “shoulder”-angle; but modern founders prefer the middle or “waist.”