220	GEMS AND PRECIOUS STONES IN THE
	ten dozen oysters, though some of the best men frequently get as many as fifteen dozen. Of course a great deal depends upon the locality. The shells average about 7,000 to the ton, and calculating the season at 150 days, each man procuring 15,000 oysters, the total of shells procured by 450 men is about 2,000 tons. Formerly, on the independent system, the divers gener­ally preferred to sell the oysters unopened for about twice the price that they would receive for the shells only, the price of shells averaging $4.50 a thousand. They went out in canoes, three, four, and sometimes five or six to each canoe, but seldom in greater number than four. The rise and fall of the tides is about twenty feet. The currents run very swiftly among the islands except just before and just after low water, and just before and just after high water ; but before and after high tide the water is too deep for divers, except in the shallowest places, which, of course, are generally exhausted, as they are always accessible. The divers claim that they can easily reach a depth of twelve fathoms when not hindered by the currents, and can remain there from a minute to a minute and a half. On reaching the place where they intend to dive, the canoe is allowed to floatK or is paddled slowly by one of the men, while the others, with their heads close to the water, are watching the bottom. Notwithstanding that the bottom is more or less rocky, they can distinguish an oyster at a depth of fifty feet. When one is observed, the diver goes down, and if there are several in the place (it is said that there are always two) he brings up all he can secure during the minute or two he is down. If a spot is found where the oysters are abundant, a basket is sunk by means of stones, having a rope attached, and the diver can sometimes fill it in a few minutes, coming up occasionally to take breath. Those in the canoe take turns in diving, in paddling, and in resting, so that of the three or four in a canoe, not more than one dives at a time. The divers take no food whatever on the day they intend to dive, unless the hours for diving are to be very late in the day, when they take a little broth in the morning. They go down with stomachs as nearly empty as possible, so that the action of the lungs may not be interfered with.