448 BULLETIN OF THE BUREAU OF FISHERIES. 
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the wristbands of the suit and by sudden eruptions of large ones discharged 
from the relief valve, which he opens from time to time by throwing his head 
back against the helmet. 
He regulates the air supply with two purposes in view—respiration and a 
proper degree of buoyancy in his suit. If all is working properly the suit is 
always more or less inflated, and in spite of the great weight of the man and his 
armor, 350 to 400 pounds as weighed in air, he treads the bottom with a pressure 
of but a few pounds. Should insufficient air be liberated the suit becomes still 
more inflated and its buoyancy will carry him to the surface, a method frequently 
employed in making ascent from moderate depths, but liable to produce serious 
hygienic consequences if practiced under greater pressures. If thepump be 
working too rapidly or too slowly he gives the proper signal by jerking on the 
life line, and the supply of air is modified accordingly. 
In moving over the bottom the divers do not walk as do persons on land, a 
thing impossible owing to their levity and the resistance of the water. Their 
movements are rather a series of headlong springs or dives upward and forward 
with the body strongly inclined. 
As the diver finds the sponges, which in the region in which the work is 
carried on are of but four kinds—sheepswool, yellow, wire, and grass—he tears 
them loose and places them in the bag, which when full he signals to have pulled 
up on the life line and an empty one sent down. When he wishes to come up, 
he gives the signal and walks toward the side of the boat, the direction of which 
he can determine by the trend of the life line, or else he buoys himself to the sur- 
face and is hauled in hand over hand, rotating and rolling like some monstrous 
form of the deep, with the air whistling and gasping at intervals from the relief 
valve. Reaching the ladder, he laboriously ascends with the assistance of one or 
two members of the crew, his helmet is taken off, and, unburdened of his chest 
and back weights, he comes aboard to be relieved by his diving mate. 
The length of time that a diver can safely stay submerged depends upon his 
physical strength and endurance, but especially upon the depths in which he’ 
works. On the Florida coast, where sponging is generally carried on in less 
than 60 feet, the usual shift is about two hours down and two ha but fairly 
good divers can stand longer shifts. 
The maximum depth at which divers can work has been a matter of dispute 
among the spongers, but there is no doubt that they can go much deeper than 
they have ever yet gone on the Florida coast (about 110 feet), though at the 
greater depths their efficiency decreases and they become subject to serious 
maladies, which will be discussed later. The laws of Greece, for humanitarian 
reasons, prohibit diving at greater depths than 38 meters (125 feet), but it is 
said that the Mediterranean sponge divers sometimes work in 40 fathoms (240 
