energized, a magnetic field is created in the orifice and 

 the shot cannot drop. When the circuit is opened, the 

 magnetic field no longer exists and the ballast drops. By- 

 means of these magnetic valves, careful control can be 

 maintained of the ballast dropping process. Because of its 

 fine particle size (about the size of a "BB"), the ballast in 

 water acts much as a dense fluid rather than as a collection 

 of individual weights. At the rate of 1 ton per 3000 feet, 

 the 16 tons of steel shot ballast carried by the bathyscaph 

 is more than enough for even the deepest dives, and pro- 

 vides an adequate safety factor. In addition, should the 

 orifices become clogged in some way, the ballast tubs can 

 be jettisoned by throwing a switch inside the sphere. 

 Switches are fitted to the magnetic valve and the tub holding 

 circuits, permitting reversal of polarity in these circuits 

 to obviate problems caused by residual magnetism. To 

 date, it has not been necessary to employ either of these 

 emergency measures. 



To maintain stability of the bathyscaph at a midwater 

 point, it is necessary to alternately drop ballast and re- 

 lease gasoline. At a depth of 1000 feet, for example, the 

 craft gradually becomes heavier due to slow cooling of the 

 gasoline. The pilot, therefore, has to continuously meter 

 out ballast to maintain his position; should he meter out 

 slightly too much ballast, the craft would begin to ascend 

 and, as it headed for the surface, the expanding gasoline 

 would cause an increase in speed and, finally, the dive 

 would be aborted. To prevent this happening, the float is 

 fitted with a separate 12 00 gallon gasoline tank called the 

 maneuvering tank from which the pilot can release gasoline. 

 This tank has a magnetically activated valve that permits 

 the gasoline to flow out and sea water to displace it. Also, 

 it is isolated from the rest of the system so that, if the 

 valve should fail, the craft could not lose all its gasoline 

 load and become too heavy to come back to the surface. 

 With all the gasoline evacuated from this small tank, the 

 bathyscaph is 3000 pounds negatively buoyant. Thus, even 

 if the valve should jam open, only 3000 pounds of buoyancy 

 would be lost, and this would not be a problem as the 

 empty ballast tubs weigh more than 1500 pounds each. 



An additional maneuvering feature was added during 

 the recent reconstruction. Vertical motors were fitted, 

 one in each of the two ballast tanks at the ends of the float. 

 These vertical motors operate in a tunnel or tube and exert 

 a vertical thrust of some 2 00 pounds in either direction. 

 Activation of these motors assists in maintaining the bathy- 

 scaph in a hovering position. By combined use of these 



