The Persian Gulf is nearly 600 miles long, with an average width of somewhat more than 100 miles. The Strait of Ormus—thirty to sixty miles wide—connects it with the Gulf of Oman, which opens directly into the Arabian Sea. The depth of water rarely exceeds thirty fathoms. Oyster reefs are well distributed throughout the gulf, and are in greatest abundance on the Arab side between the 24th and 27th degrees of north latitude and the 50th and 54th degrees of east longitude, at a distance of from a few hundred yards to sixty miles from the shore, and especially in the vicinity of the Bahrein Islands. The oysters are scattered over level areas of coral rock and sand, with depths ranging from two to eighteen fathoms.[100] The divers rarely descend in deeper water than twelve fathoms, notwithstanding that valuable pearls are apparently obtainable at greater depths. Although the British Protectorate extends over the Persian Gulf, insuring the peaceful prosecution of the fisheries and the settlement of intertribal contentions by the government resident, the fisheries are under the regulations of the maritime Arab sheiks. The restrictions imposed by these, however, are principally with a view to collecting a revenue from each boat employed. The total amount realized thereby is unknown, but there is good reason for supposing that it is considerable. [Illustration: AGHA MOHAMMED (1666–1725) Founder of the present Persian dynasty From a Persian manuscript in the library of Robert Hoe, Esq. ] [Illustration: SHAH SULAIMAN (1647–1694) From a Persian manuscript in the library of Robert Hoe, Esq. ] The fisheries are carried on during the greater part of every year, presenting a strong contrast to the Ceylon fishery, which is prosecuted usually less than forty days, and in only about one year in three on an average. This is especially remarkable when it is considered that no particular care is taken of the Persian reefs and, except for certain tribal restrictions, the fishermen may work whenever and wherever they choose. Owing to the extended area over which the fishing is prosecuted and the existence of undisturbed breeding-oysters in the deeper waters, the reefs are not readily exhausted, notwithstanding the tens of millions of mollusks annually removed therefrom. The fisheries are at their height from June to September, when nearly every person on the coast is interested in some capacity, if not in fishing, at least in furnishing supplies, cleaning shells, buying pearls, etc. In April and May the water on the deep banks is so cold that the fishermen confine their efforts to the more shallow areas. During the winter months, the cold weather and the northwesterly gales interfere with the work, except such as is prosecuted in the smaller bays and inlets.