provide vertical motion either ascending or descending, and 

 one is installed athwartships for turning. The motors all 

 drive propellers through gear boxes. Special features of 

 the motors include epoxy coating of the armature to lessen 

 windage losses, and helical grooving of the commutator to 

 provide a wiping action on the carbon brushes to prevent 

 excessive buildup of an insulating oil film between brushes 

 and commutator. As mentioned before, motor control is 

 effected via control circuitry from the sphere to the topside 

 control box. 



Mo tor locations 



Ballast 



The ballast system of the bathyscaph consists of two 

 steel ballast tubs located in recesses in the bottom of the 

 float. Each tub is held in place by a chain that passes up 

 through the float and is attached to a large electromagnet 

 on the topside of the float. This system gives the operator 

 the opportunity, in case of emergency, of jettisoning the 



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