In the construction of the Trieste we simplified the system and 

 rendered it more flexible by making use of only one of the means 

 worked out for the FNRS 2. The ballast consists of 9 tons of iron 

 pellets contained in two metal tubs together weighing 2 tons. (See 

 Fig. 9.) At the base of each of these tubs is placed a magnetic valve 

 permitting the ballast to be released. Moreover, each tub is suspended 

 from an electro-magnet: thus the ballast can be released in small 

 portions by means of the magnetic valves : the two tons weight of the 

 tubs constitutes an emergency ballast which can be dropped by cutting 

 off the current to the electro-magnets. Besides, if necessary, such as 

 would be the case if the valves were stopped up, the pilot could always 



Ê/ectro-mogner holding Jever supporting 

 ballosl tub \joallasl tub 



Lever and magnet for trail-rope 



L 



^ W uit^i ii j^^texri 



l^^^^r 



^OT 



Ballast tub 



Ballast valve 



Large window 



Antechamber 



Fig. 9. Side elevation of the Trieste 



drop at one blow all the iron pellets with the tubs. (The detail of the 

 valves and the electro-magnets will be found described in the 

 Appendix.) 



Suffice it to say that the iron in the valve, when magnetized, forms 

 into a solid block, and stops up the outflow pipe at the point where its 

 cross-section decreases. Figs. 16 and 17 explain the working. 



CHAMBER LEADING TO THE CABIN 



The passengers of the FNRS 2 entered the cabin while the bathy- 

 scaphe was still in the hold of the parent ship. As the Trieste had to be 

 launched in the port, it was necessary to arrange that the crew should 

 not have to remain shut up in the cabin during the whole journey 



[80] 



