Popular Science Monthly 



655 



water; if that should come into contact 

 with the liquid of the battery, chlorine 

 gas — the poison gas of European battle- 

 fields — would fill the vessel. 



Although the Edison cell will not 

 generate chlorine, even if salt water 

 should leak in, it does generate an ex- 

 cessive amount of hydrogen when dis- 

 charging. Whatever type of cell may be 

 installed the storage battery is heavy, 

 cumbrous, dangerous and very limited 

 in the amount of power that it is able to 

 deliver. 



Realizing that the submarine must be 

 freed of tht, storage battery, the Na\^ 

 Department has taken a great interest in 



Open superstructure 



company spent about $130,000 m com- 

 pleting a submarine boat, seventy-five 

 feet long and seven and one-half feet 

 in beam. It was driven only by oil en- 

 gines; it had no storage batters' at all. 

 In order that the crew might live despite 

 the poisonous gases given off by the en- 

 gines, a compressed air ventilating sys- 

 tem was installed. The six men on board 

 stayed under water thirty-six hours — 

 a record submergence. 



It was in this boat that Mr. Neff be- 

 came interested. He made improve- 

 ments of his own and engaged engineers 

 to contribute their ideas. A trial board 

 appointed by the Na\^ Department ap- 

 proved of the ventilating and propulsion 



minutes — a feature of importance 

 when the submarine is cruising at the 

 surface in a heavy sea and the atmos- 

 pheric air-feed may be cut off mo- 

 mentarily. 



The air bottles are tapped as they are 

 needed. A high-pressure airline 

 leads from these bottles throughout the 

 vessel; the high pressure system in turn supplies 

 a low pressure system of pipes. As soon as the 

 atmospheric air-feeding devices have been cut off 

 the air pressure within the vessel drops; and 

 this drop is utilized to cause the feeding of air 

 automatically from the stored supply. 



The exhaust from the engine passes out 

 through an exhaust manifold from which an 

 rxhaust-pipe leads, discharging beneath the pro- 

 pellers. iMechanical exhausters are also pro- 

 vided in case the water pressure is so great that 

 the natural suction effect produced by the travel 

 of the vessel through the water is insufficient. 



wliat is known as the Xcff system of 

 submarine propulsion, which takes its 

 name from Abner R. Neff. 



About three years ago a California 



system. The only objections which 

 have been raised to the system are 

 military in character. Against the 

 Neff system it has been urged that 

 large quantities of air would be 

 emitted, when the submarine is 

 running under water ; a wake of air 

 bubbles would be left on the sur- 

 face to betray the craft and to make it 

 easy to follow its submerged course. An- 

 other objection is the noise made by the 

 Diesel engines under water; the pounding 

 of engines and air compressors could 

 easily be picked up by sensitive sound- 

 receiving devices. 



As might be supposed, the inventors of 

 the Neff submarine system are ready 

 with replies. They point to the manner 

 of handling the exhaust from the en- 

 gines — indicatcfl in a general wa\' in the 

 accompanying illustration. The burnt 

 gases are led to a system of condensing 

 tubes outside of the hull. The expanded 

 gases, having been condensed, are drawn 



