form of the same capacity. Therefore the cylindrical form is the 

 strongest. 



Again, the construction of a hydrodynamic ship's hull costs more 

 than that of a simple cylinder. The plates which are to form the bottom 

 of a ship must be designed individually, and each of them has a different 

 curvature. In our cylindrical hull the sheets, with the exception of the 

 foremost and aftermost, are all of the same form and same curvature. 



Appendix 4 



Transverse Partitions of the Float 



These must meet several requirements : 



1. They contribute to the solidity of the hull. Without them, the 

 hull, lifted up at both ends by two waves, could fold like a rubber 

 tube, by flattening in the centre. 



2. They must be strong enough to resist variations in pressure if, 

 accidentally, during the decanting of the petrol into the float, one of 

 the compartments were completely filled while its neighbour still held 

 only air. 



3. To permit changes of volume of the petrol due to variations of 

 temperature and pressure, without any loss of the precious liquid, the 

 float must contain in its lower part a certain quantity of water. The 

 stability of the bathyscaphe would be poor if this water, heavier than 

 the petrol, could move about freely in the float and accumulate at one 

 of its extremities, thus accentuating any initial disturbance of equili- 

 brium in the machine, however slight. 



4. It must be arranged so that if one of the compartments is flooded 

 by water, following a leak, the change of trim which results must not 

 be too great. That is why we have progressively decreased the volume 

 of the compartments situated closer to the extremities. 



5. If by ill-luck a leak occurs and one of the compartments is 

 entirely flooded, the loss of the sustaining liquid must be able to be 

 compensated by the unballasting of emergency ballast. Also the 

 minimum quantity of this emergency ballast can be determined if we 

 require that, during an empty test, the bathyscaphe is able to rise even 

 if the cabin has been flooded. If we do not want to exceed this mini- 

 mum ballast, the maximum volume of a compartment is limited by 

 the condition that this same ballast must be suflicient to save the 



[161] 



