DESCRIPTION OF THE BATHYSCAPH 



Before proceeding into the program and results, it is desirable to familiarize the 

 reader with the construction and capabilities of a bathyscaph. The two Greek root 

 words bathy and scaph mean deep and boat, respectively. The bathyscaph is a self- 

 contained, untethered, deep-diving vehicle. It may be likened to an underwater version 

 of a nonrigid, lighter-than-air ship. Basically, it consists of a heavier-than-water manned 

 sphere capable of withstanding the great hydrostatic pressures encountered in the ocean 

 depths (fig. 1 and 2). The sphere is the only component of the craft that is strong 

 enough to resist destruction by the great pressures. This sphere is suspended below 

 a nonrigid buoyant hull which is filled with gasoline and is capable of withstanding 

 the buffeting of surface waves and towing but not the hydrostatic pressure of the deep 

 sea. Equilibrium between external and internal pressures about the float is maintained 

 by allowing the sea water, which is immiscible with and heavier than gasoline, to enter 

 the hull through special "breathing" valves. Vertical movement of the bathyscaph is 

 controlled by changes in buoyancy. Diving is initiated by flooding air-filled tanks at 

 each end of the hull and the entrance tube leading to the sphere with sea water. The 

 bathyscaph then commences to sink. As it settles into the ocean, the gasoline is com- 

 pressed by hydrostatic pressure causing an additional loss in buoyancy. The tempera- 

 ture of the gasoline is also lowered by the decrease in ambient sea-water temperatures 

 with depth. Such contraction of the gasoline adds further to the decrease in buoyancy. 

 With only minor control in the buoyancy, the bathyscaph will confinue to sink at about 

 6000 feet per hour until it reaches the bottom. Return to the surface is accomplished 

 by jettisoning enough of the iron shot used as ballast to regain positive buoyancy. Fur- 

 ther control of buoyancy can be attained by liberating gasoline from a special com- 

 partment. The bathyscaph can be made to hover momentarily at mid-depths or to rest 

 on density discontinuities within the ocean by these control mechanisms. At the sea floor, 

 the descent is dampened by a loss in negative buoyancy as the steel cable guide rope 

 hanging below the bathyscaph gains support from the sea floor. 



Although the primary movement of the bathyscaph is in the vertical direction, some 

 horizontal maneuverability is provided by propellers driven by electric motors mounted 

 on the upper deck of the hull (fig. 2). A horizontal speed of about 1 knot can purportedly 

 be maintained for 4 hours. 



The sphere of the TRIESTE has an inside diameter of 2 meters with a minimum wall 

 thickness of 9 centimeters which increases to 15 centimeters in the vicinity of the port 

 and hatch. It can accommodate two people and approximately 3 cubic feet of instru- 

 mentation without difficulty. The sphere, forged out of "fatigueless" steel, is designed 

 to withstand the pressure at a depth of 15 kilometers (22,500 psi) before collapsing and 

 is considered safe to dive to 6 kilometers. The cabin has two portholes — one looking 

 forward and slightly down, the other aft and upward. The ports consist of truncated 

 right-angle cones of plastic 15 centimeters thick, and are 40 centimeters and 10 centi- 

 meters across on the outside and inside, respectively. This provides a 90-degree field 

 of view. Surrounding the forward port, there are twelve separate lead-throughs into 

 the cabin. Two of these are used for snorkels; in times of emergency, it is possible to 

 take in air while at the surface. The remaining lead-throughs provide electrical cables 

 and manometer tubing for the operation of the bathyscaph and its scientific equipment. 

 The entire power supply (30 kwh dc, provided by silver-zinc batteries) for the TRIESTE 

 is contained wholly within the sphere. 



