to the diving site. From this arose the need to reach our cabin in the 

 open sea, when this cabin would be 13 ft. below the surface of the 

 water. This was how we did it. A tube h I? o( 3. diameter of 25 in. 

 (Fig. 7) traverses the entire float from top to bottom and ends beside 

 the cabin in a little space which we called the antechamber (see Fig. 7, 

 Fig. 9 and Plate XI). The top of the tube can be closed by the normal 

 circular hatch seen in submarines and ends in the conning-tower on 

 deck. On the surface this shaft is generally empty : it is entered by a 

 ladder and one gets into the cabin by sliding through the door, shaped 

 like a truncated cone, which gives access to it. This door is closed and, 

 by means of a pump on the towing vessel, the shaft is filled with water. 

 Then the upper hatch is closed. The bathyscaphe is then ready for the 

 descent : it will suffice to open the air tanks for it to dive. 



After the dive the shaft must be emptied. For this purpose the 

 occupants of the cabin have ready bottles of compressed air which 

 they direct into the shaft by means of a small steel tube. Thus the 

 water in the shaft is driven out through a large tube which leads from 

 the bottom of the antechamber to above the deck. 



One can also make use of compressed air from the towing vessel 

 to empty the water-lock without action on the part of the passengers. 

 This is necessary during empty dives and is useful when one wants to 

 economize with the bottles of compressed air in the cabin. 



The use of the pump to fill the shaft with water could have been 

 avoided, for example, by placing a sluice gate at the base of the shaft 

 or by equipping the bathyscaphe with its own pump, but after study 

 the system chosen appeared the most suitable, at least for the first dives. 



The door of the cabin has a porthole in plexiglas which allows one 

 to see into the antechamber : the wall of the antechamber facing this 

 porthole has a large window in plexiglas i-i8 in. thick, 33-5 in. high 

 and 23-6 in. across. This window never has to sustain a difference of 

 pressure of more than a few fathoms of water, since in a dive the shaft 

 is in communication with the outside water through the large tube 

 we have mentioned. Hence the thickness of i-i8 in. for the plexiglas 

 is quite enough. This plate of glass is a beautiful industrial achievement 

 that we owe to Vétrocoke. Through the porthole of the cabin and the 

 large window the observers enjoy very good visibility in this direction, 

 always provided that the water introduced into the shaft is perfectly 

 clean. The Trieste thus possesses two portholes giving broad fields of 

 outside vision, while the FNRS 3 has only one that is really of use. 



[81 ] 



