Bells.
Bells are made of a mixture of about three parts of copper to one of tin, and sometimes a portion of silver, according to the shape and size the bell is to be. They are cast in moulds of sand—the melted metal being poured into them.
The parts of a bell are—its body, or barrel; the clapper, within side; and the links, which suspend it from the top of the bell.
The thickness of the edge of the bell is usually one fifteenth of its diameter, and its height twelve times its thickness.
The sound of a bell arises from a vibratory motion of its parts, like that of a musical string. The stroke of the clapper drives the parts struck away from the centre, and the metal of the bell being elastic, they not only recover themselves, but even spring back a little nearer to the centre than they were before struck by the clapper. Thus the circumference of the bell undergoes alternate changes of figure, and gives that tremulous motion to the air, in which sound consists.
The sound which the metal thus gives, arises not so much from the metal itself, as from the form in which it is made. A lump of bell-metal gives little or no sound; but, cast into a bell, it is strikingly musical. A piece of lead, which is not at all a sonorous body, if moulded into proper shape, will give sound, which, therefore, arises from the form of the object.
The origin of bells is not known; those of a small size are very ancient. Among the Jews it was ordered by Moses, that the lower part of the blue robe, which was worn by the high priest, should be adorned with pomegranates and gold bells, intermixed at equal distances.
Among Christians, bells were first employed to call together religious congregations, for which purpose runners had been employed before. Afterwards the people were assembled together by little pieces of board struck together, hence called sacred boards; and, lastly, by bells.
Paulinus, bishop of Nola, in Campania, is said to have first introduced church bells, in the fourth century. In the sixth century they were used in convents, and were suspended on the roof of the church, in a frame. In the eighth century an absurd custom of baptizing and naming bells began; after this they were supposed to clear the air from the influence of evil spirits.
Church bells were, probably, introduced into England soon after their invention. They are mentioned by Bede, about the close of the seventh century. In the East they came into use in the ninth century.
In former times it was the custom for people to build immense minsters, and to apply their wealth in ornamenting their places of worship. The same spirit made them vie with each other in the size of their bells. The great bell of Moscow, cast in 1653, in the reign of the Empress Anne, is computed to weigh 443,772 lbs.
Bells are of great service at sea during a very dark night, or thick fog; they are kept, in such cases, constantly ringing. Near the Bell Rock light-house, in England, as a warning to the mariner in fogs or dark weather, two large bells, each weighing 1200 lbs., are tolled day and night, by the same machinery which moves the lights, by which means ships keep off these dangerous rocks.