are fixed to a common rod d. Thus the pressures of the liquid, acting 

 upon one of the flaps from the bottom upwards and upon the other 

 from the top downwards, always compensate each other exactly. 

 At the top of the rod is fixed the soft iron core e which will be attracted 

 by the magnetic field at the moment when the coil /is energized. 



Fig. 27. Compensated control valve 



Fig. 27 shows better than Fig. 26 some constructional details, 

 especially the soft iron armature, A, /, ^, which will conduct the 

 magnetic flux. 



Before our departure for Ponza, we lacked time to work out this 

 valve. But I have now constructed it and it works perfectly. 



[i8i] 



