devices (ballast, gasoline, and motors), the bathyscaph 

 can be maintained in a midwater position within 10 or 15 

 feet of the intended depth. However, much still depends 

 on the proficiency and experience of the pilot. 



Landing on the sea floor is accomplished easily through 

 the use of a Fathometer which gives some 200 fathoms of 

 warning before actual contact with the sea floor. The pilot 

 can watch the Fathometer and gauge his rate of descent so 

 that, as he approaches the sea floor, he can slow down to 

 a rate of a foot or so per minute and make a smooth landing. 

 Normally, at about 2 00 feet from the bottom, the outside 

 lights are turned on, and at 60 feet the pilot is able to see 

 the back reflection of the bottom through the front window. 

 At 30 feet, he will see the bottom. With this slow rate of 

 descent, he can easily abort the landing by the control 

 method described in the previous paragraph if the presence 

 of a large rock structure or some other undesirable terrain 

 feature should make landing unfeasible. He would then turn 

 on his propulsion motors, move to another area, and try 

 the landing again. 



Another device borrowed from aerial balloon opera- 

 tions and used for the landing is a guide rope consisting of 

 an 80-foot steel cable that is suspended beneath the bathy- 

 scaph. If the craft is trimmed so that it is only a few pounds 

 heavy as it approaches the sea floor, it should attain equilib- 

 rium riding on the end of its guide rope through the loss in 

 negative buoyancy as the cable gains support from the sea 

 floor. This equilibrium, of course, is not permanent 

 because cooling of the gasoline will eventually make the 

 craft heavy and cause it to settle to the bottom. The pilot, 

 by manipulating the shot valve, can counteract this effect. 

 The guide rope also tends to provide a lateral stabilizing 

 effect, if there is any current at the bottom, by acting as 

 a sort of "sea anchor. " Finally, the pilot can throw a 

 switch and jettison the guide rope by means of a magnetic 

 release, if it should become fouled on the bottom. 



Upon completion of observations at the bottom, the 

 pilot releases ballast, watching the Fathometer and the 

 sea floor. As the craft starts to leave the bottom, he stops 

 dropping ballast. The craft will become lighter once the 

 ascent is started, gradually accelerating as it goes upward. 

 Release of only a modest amount of ballast is normally 

 required for ascent. There is no control over the ascent, 

 and this part of the operation is normally not scientifically 

 useful. The only way the bathyscaph could actually be 

 slowed would be to release gasoline from the main tank 



