490 BULLETIN OF THE BUREAU OF FISHERIES. 
work rapid decompression is guarded against by gradual transition from higher 
to lower compressions in the air locks, or in carefully regulated diving with 
the scaphander by slow ascents, but in sponge diving these precautions are 
ignored, with the result that many of the divers become paralyzed and a consider- 
able number of them arekilled. Flegel states that the average yearly mortality 
among the Mediterranean divers reaches the almost incredible proportion of 
nearly 20 per cent, and the cases of more or less serious illness about 25 per 
cent. He states, further, that during thirty-nine years upward of 5,100 sponge 
divers were killed by their work and 2,100 were so paralyzed as to be incapacitated. 
That the results of sponge diving are so serious is not surprising in view of 
the practices obtaining. I am informed by various authorities that the machine 
divers in the Mediterranean go to a depth of 250 feet, remaining on the bottom 
three or four minutes at each descent. Boats working in these depths carry 12 
or 13 divers, each of whom has a rest of about two hours between plunges. 
Though the pressures are so great that the heavy woolen stockings worn by the 
divers are pressed deeply into the flesh, no measures are taken to ascend gradually, 
the claim being made that the more quickly the person is removed the less the 
liability to injury. Sponge divers have informed me that serious cases of “ bends” 
occur more frequently in depths less than 25 fathoms than in those greater, 
owing to the shorter time to which the diver is subjected to the pressure in the 
latter case. 
On the other hand the highest scientific authorities on diving place the safe 
limit for physically sound men at 150 feet, and they all prescribe a slow ascent 
and a gradual release from pressure as an essential element of safety. In 
caisson operations, where the conditions under which the men are working are 
essentially the same as those in a diving dress, the compulsory use of air locks 
for gradually reducing the pressure on workers making the exit has been found 
absolutely necessary to preserve the health of the workmen. It appears that 
the incentive to deep diving is imposed largely by the financial conditions under 
which the fishery is conducted. The masters of the vessels, having little capital, 
are obliged to borrow at rates as high as 25 per cent, and feel Scie to force 
their divers in order to make their ventures pay. 
In many parts of the Mediterranean the sponges grow on bottoms covered 
with vegetation, the location being often indicated by a mere hiatus in the 
tops of the growth. In working on such bottom the diver lies almost hori- 
zontally above the vegetation, looking for the telltale spots and locating the 
sponges by feeling with his hands. 
About the islands of the Ajgean many sponges are attached to the faces of 
submarine cliffs 50 or 60 feet high, and to reach them the diver floats himself by 
regulating the air pressure in his suit and propels himself from place to place by 
a swimming motion of the hands. 
