The pearl-fishery at the Bahreen islands, in the Persia] Gulf, is the most extensive and the most valuable in th world. It formerly belonged exclusively to the Persiam but a powerful tribe of Arabs have now obtained a slim' in it. The oyster banks extend from to 40' North Lat.; they have from fifteen to thirty feet of Ovate over them, and some even more. The method of fishin does not differ materially from that practised at Ceylon it commences in June, and is carried on for two months the divers employed are Persians. The boats are al numbered ; the oysters are not allowed to be opened in th boats, but are brought ashore at a certain hour, and open ed in presence of an officer. The pearls found are car ried to the collector, who receives the duty, which is on third, and which is daily paid in pearls or money. Th pearls of this fishery are of a golden yellow colour ; an though not so much valued in Europe as those of Ceylor are more esteemed by the Indians, on account of their al ways retaining their colour, whereas the white ones ar liable to tarnish, and soon lose their lustre. The shells ar nearly of a round form, from eight to ten inches in diame • ter, and thick in proportion. They are the property c the divers; and are partly sent up the Red Sc i, and thenc to Grand Cairo and Constantinople; many of them ar carried to India, and thence to China, where they ar manufactured into a great variety of useful articles.
The principal situations in America, where pearls ar found, are, the arm of the sea between the islands of Cu bagua and Coche, and the coast of Curnana ; the mouth c the Rio de la Hacha; the Gulf of Panama near the Islas d las Perlas; and the eastern coast of California. Long befor the.discovery of America pearls were highly valued by th natives; and the Spaniards, on their conquest of the coot try, found large quantities of them in different quarters. an early period the fisheries were very productive ; i 1587, 697 lbs. of pearls were imported into Seville, tmon which there were some of great beauty for Philip I The same monarch had one from the fishing of St. Ma queriti, which weighed 250 carats, and was valued 150,000 dollars. The only places, however, where then
are still fishing establishments, are the Gulfs of Parma] and California ; and the number of pearls which they pre duce is now reduced almost to nothing. The decline • these fisheries seems to be solely owing to improper mt nagement, and to the small encouragement given to the It dians and negroes, who follow the occupation of diver The pearls of California are large and of a beautiful water, but are frequently of an irregular and disagreeable shape.
Pearls are of a calcareous nature, and consist of a num ber of coats or layers, regularly spread over one another Eke the coats of an onion. They seem to be the effects of disease, like bezoars and other stones in different animals, and are formed by an extravasation of a glutinous juice either within the body or on the surface of the animal. Such extravasations may be caused by the admission of particles of sand or other heterogeneous bodies along with the food, which the animal, in order to prevent the dis agreeable effects of friction, covers with its glutinous mat ter ; which, as it is successively secreted, forms many re gular lamellae. Accordingly, in the centre of the pearl, there is often found a small particle of sand or other extra neous matter, which may be considered as the nucleus or primary cause of its formation. When the first coat is separated, a worthless impure pearl is frequently found below, and sometimes the lamella are clear and impure by turns. This view of the formation of the pearl is render ed still more probable from the manner in which the Chi nese are said to force the oysters to produce pearls. In the beginning of summer, when the oysters rise to the surface of the water and open their shells, five or six beads made of mother-of-pearl are strung on a thread and thrown into each of them ; and at the end of the year, when the oysters are drawn up and opened, the beads are found covered with a pearly crust, so as to have a perfect re semblance to real pearls. See the article CEYLON. Per cival's Account of Ceylon ; Asiatic Researches, vol. v.; and Humboldt's Political Essay on New Spain, vols. ii. and hi.