the entire vehicle can be accommodated (see 

 Table 5.6). 



Historically, pressure testing programs 

 proceeded along lines which started from 

 unmanned, tethered or untethered dives and 

 grew progressively deeper to the vehicle's 

 maximum operating depth and to some point 

 beyond (test depth). Beebe's BATHY- 

 SPHERE was lowered on a cable; Auguste 

 Piccard's FNRS-2 was equipped with a depth 

 gage that dropped ballast at a pre-set depth, 

 and a timer that performed the same task if 

 the depth gage failed to function. In the 

 event that Fl\RS-2 drifted into shallow 

 water, an antenna-like object was affixed to 



strike the bottom first and dump ballast 

 before the vehicle struck the bottom. In both 

 BATHYSPHERE and FNRS-2, the ability of 

 the pressure hull to withstand the deep pres- 

 sures was observed merely by the presence 

 or absence of seawater inside the sphere. 



When large vehicles of the ALUMINAUT 

 variety appeared, pressure tests began with 

 the finished vehicle making progressively 

 deeper, manned dives and conducting strain 

 gage readings on each dive. ALVIN, on the 

 other hand, was sent down initially un- 

 manned to 7,500 feet on a tether before 

 manned dives to 6,000 feet were conducted. 



Vehicles of the PAULO I variety (Fig. 5.21) 



Fig 5,21 PAULO I (now SEA OTTER) entering a test tank for pressure testing (Anautics Inc.) 



269 



