driving power. The rate of precession of this unit is 

 acceptable over the short duration of the average dive. 

 As this unit is not a gyrocompass but a gyrodirectional 

 indicator, the heading must be set prior to diving so that 

 a true heading reference is available while operating. 



2 3. EDGERTON CAMERA SYSTEM 



The Edgerton cameras now fitted to the bottom of the 

 float are of improved design compared with those originally 

 used. The interior circuitry, the design of the case, and 

 the design of the front window have all been modified in 

 light of recent experience with these units. Two cameras, 

 one oblique and one vertical, are now carried instead of the 

 one that was formerly used. In addition, two Edgerton 

 stroboscopic units are fitted to provide lighting for these 

 cameras. These stroboscopic lights can be synchronized 

 with the internally carried Hasselblad camera so that it 

 also can utilize the external flash units. 



24. AIR REVITALIZATION SYSTEM 



The original air system consisted of an oxygen bottle 

 from which metered oxygen was used to operate a Venturi 

 device. The vacuum caused by the oxygen flow was used 

 to pull air from the sphere through carbon dioxide absorbent 

 arranged in flow-through containers. This method did not 

 permit the flexibility that was required, and the apparatus 

 was bulky. 



The new air system consists actually of two basic 

 systems. The oxygen is supplied by a 38- cubic-foot oxygen 

 bottle with a pressure of 2 000 psi. The oxygen is metered 

 manually through a regulator valve and pressure gauge 

 arrangement on the bottle. The carbon dioxide absorbent 

 system consists of three absorbent canisters attached to 

 a manifold through which air is drawn by a small electric 

 fan. The chemical canisters themselves are of the same 

 flow-through design. Oxygen/ carbon dioxide ratio is 

 maintained by manually operating the regulator on the 

 oxygen bottle and the suction motor on the carbon dioxide 

 absorbent manifold. Percentages of the two gases are 

 determined from an indicator panel. 



44 



