Fig 11, 9 ALVIN's jettisonable bottom sampling aluminum brow. All the designated sampling devices are employed by ttiemanipulatorwhlcti is also used to collect grab samples The 

 dredger is employed by making ALVIN negatively buoyant and pushing the dredge into the sediment (WHO!) 



ulator while the diamond cutting bit rotates 

 and water flows through the drill to flush 

 away mud generated through cutting. At 

 desired penetration, drill rotation is re- 

 versed, as is water flow, and the drill assem- 

 bly is rocked slightly to assist in seizing and 

 breaking off the core specimen. The core is 

 held in the hollow corer by the reverse water 

 flow until ejected into a sample container by 

 once again reversing the flow of water. 



The tethered GUPPY employed a more di- 

 rect, brute-force approach to hard rock cor- 



ing. A Schlumberger Side Wall Corer was 

 installed outside the pressure hull and aimed 

 horizontally to fire hollow bullets into an 

 outcrop. The resulting sample is about 1 inch 

 in diameter by 2.5 inches in length. The corer 

 has a capacity to take 24 individual samples 

 on one dive. Mr. William Watson, of Sun 

 Shipbuilding and Dry Dock, relates that sev- 

 eral hundred samples were collected in this 

 manner, but he acknowledges that an assess- 

 ment of the effects on viewports and other 

 structures is in order. The pressure wave 



551 



