necting hose is extremely light and flexible, never carrying a pres- 

 sure of more than ten atmospheres. In case the hose should be cut, 

 or the surface supply should fail, the diver carries a small high- 

 pressure cylinder which gives him several minutes of air, depending 

 on his depth. As with the aqualung, the diver must wear a suit for 

 warmth, and he may wear either fins or boots, according to the 

 nature of his work. 



Two devices scarcely off" the secret list promise important break- 

 throughs for submarine archaeology. One is Cousteau's plunging 

 saucer, a disk-shaped, miniature, two-man submarine propelled by 

 water jets and fitted with outside mechanical arms. Almost more 

 remarkable is the self-contained breathing apparatus designed by 

 the Swiss, Hannes Keller. With it he has dived to 720 feet, and it 

 has been tested in a tank to a depth of 820 feet. This is an enormous 

 achievement when we consider that the normal, absolute limit for 

 safe diving with regular air is 500 feet. Below this depth both 

 oxygen and nitrogen become poisonous. In 1956, however, a 

 British team made a series of dives off' Norway culminating in 

 George Wookey's world-record dive of 600 feet. But Wookey used 

 an advanced form of standard gear and was supplied with an oxygen- 

 helium mixture in which the proportion of oxygen was much less 

 than in natural air, so that it was not toxic. The total time for the 

 dive was more than twelve hours. In contrast, one of Keller's dives 

 to 510 feet took only 58 minutes! 



Salvaging a wreck or surveying a city usually means removing 

 tons of mud or sand from around the hull, or from the buried 

 street. To do this work the archaeologist depends on two bulky 

 but standard pieces of equipment called the "air-lift" and the 

 "tunneling-lance." The air-lift consists of a large, flexible pipe 

 through the bottom end of which a supply of air is blown. As it 

 rises up the pipe, the air expands and draws a mass of water (and 

 mud or sand) with it, acting like a huge vacuum cleaner. The 

 tunneling-lance is nothing more than a glorified fireman's hose 

 that produces a continuous jet of water strong enough to loosen 

 packed mud, sand, or shingle, which is then carried away by the 

 suction of the air-lift. 



For the most part, a diver's life underwater consists of long 

 hours of drudgery, sweat, and routine. But nearly every diver 

 thrills to the exhilarating sensation of being alone in the silence of 

 deep water, and seeing for the first time an object made by a man 

 many thousands of years before. Divers who work together usually 

 develop a sixth sense for understanding each others' signs and 

 grunts underwater. If they do not, they are not good divers. Com- 

 munication with the surface party is a different matter. If a tele- 

 phone system is not available then the diver cannot dictate his 

 notes; he must record them himself. His plastic board, on which 

 he must record all survey measurements, is as indispensable as his 

 knife, underwater watch, depth gauge, and compass. 



If the site is small, such as a ^vreck and its cargo, then the best 

 surveying approach is to lay a grid of plastic tapes over the wreck, 

 as was done by Richard Garnett at Chios, and by Gianni Roghi at 

 Spargi. It was Roghi who made the first real attempt to plot the 

 arrangement of a cargo in three dimensions. 



The archaeologist who surveys a larger area, such as a city, 

 must use more complex techniques. Usually he begins by orientat- 



The aqualung, a free-diving system 

 perfected by Cousteau and Gagnan, is li.ere 

 demonstrated by a diver (Sandri Klian) 

 at a depth of a hundred feet. 



This late nineteenth-century engraving shows 

 an early version of diving equipment. 

 As with present day "standard" gear, air 

 was fed to the diver from a boat at 

 the surface. 



137 



