Fig, 11 10 Exploded view of plastic core tube, quiver and closure stopper (WHOI) 



Fig. 11.11 /(LV/Ws hard rock rolary corer (WHOI) 



from the charge was considerable and at 600 

 feet it was felt all over the submersible. 



Pry Bars and Splitters — A wide vari- 

 ety of pries and splitters has been made 

 which conforms to a specific vehicle's manip- 

 ulator hand and are used to pry or split 

 samples from hard rock. 



Geophysical Measurements 



Magnetics: 

 Operation: Since submersibles are made 

 primarily of steel, magnetic measurements 

 must be made so that the sensing device is 

 beyond the influence of the vehicle. In the 

 case of ALUMINAUT a boom only 8 feet long 

 provided sufficient isolation (12), while the 

 steel-hulled BEN FRANKLIN required that 

 the sensor be buoyed in a glass sphere 150 

 feet above the submersible (Fig. 11.12). The 

 total magnetic field strength is indicated by 

 measuring the precession rate of polarized 

 hydrogen nuclei in the sensor. The generated 

 frequency is amplified, counted, and dis- 

 played in gammas and recorded on a strip 

 chart or digitized. 



Data: Measures the total ambient mag- 

 netic field with respect to time over a select- 

 able range of 20,000 or 100,000 gammas to an 

 accuracy approaching ±1 gamma. 



Gravity: 



Two approaches to gravity measurements 

 have been taken, one with the submersible 

 bottomed and stable, and the second with the 

 submersible underway. In the first case, a 

 La Coste & Romberg gravimeter (Model 5) 



552 



