UNDERWATER ARCHEOLOGY — BASS 



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Figure 1. — Mapping devices, suction hose, and lifting balloon used in excavation of 

 Byzantine shipwreck during 1961. 



sides of the wreck. Two divers, sighting through simple alidades, 

 could record vectors and elevations on a surveying pole held by a 

 third diver. This proved successful for overall measurements, but de- 

 manded great clarity of the water and the use of three divers. A 

 5-meter square mapping frame was then placed over part of the 

 wreck; this was leveled on its telescopic legs and positioned by the 

 plane tables. A horizontal beam rode across the top of the frame, 

 usins: two sides of the frame as tracks. Yoked to this beam was a 



