tain the same weight as the lare;er cyl- 

 inder and the same quantity of air, 

 You then observe tbat their weights are 

 the same in order to have sufBcien*- 

 strengbt to stand the pressure brought 

 upon them, by containing equal quantities 

 of air. 



A — But Mr. B, if the comprissed air 

 Hows from the smaller cylinder, under 

 its high pr( ssure, into the enlarged nozzles, 

 and there descend to a low pre!»>ure before 

 passing out from them, there is a much 

 greater amount of energy wanted than 

 in the case of the large cylinder; be- 

 cause the pressure of the air must descend 

 from thirty pounds per squur inch in 

 the case of the smaller cylinder, before 

 doing useful work, and in the case of the 

 larger cylinder it would only have to de- 

 scend from fifteen po\ind.i. Yuu under- 

 stand that in the case of the smaller cyl- 

 inder, the compressed air cuiiiaihs much 

 more energy than thai of the larger one, 

 although the quantity of air contained iti 

 each cylinder is the same. Now Mr. B, 

 we must necessarily have this high pres- 

 sure in order to reduce the bulk of the 

 cylinder. But 1 cannot fancy this enor- 

 mous waste of energy. Car> you suggest 

 a way to prevent this loss? 



B — Mr. A, I suggest placing an air com- 

 pressor on the ship, and alluw the stored 

 compressed air from its reservoir, to actu- 

 ate this compressor while in the act of de- 

 scending to a low pressure, and allow the 

 exhaust from the compressor, which 

 would contain sufficient pressure to supply 

 the enlarged nozzles. The compressor 

 then in return can compress more air into 

 the reservoir from which it received its 

 energy, thus there is no loss of energy 

 from that source. The utra weight ad- 

 ded in the shape of machinery, is small in 

 comparison to the power saved. Now Mr_ 

 A, with all our diflferent air-ships, (tho.se 

 useing air jets, aeroplanes, horizontal 

 screws etc.,) We have made these changes 

 and doubled their lifting capacities, with- 

 out increasing the power of the sustaining 

 motor. The fact is then clear, that we 

 can iu a similar way, increase their lifting 

 capacities without limit, so far as this 

 law is concerned The practical limit can 

 only be determined by experiment. In 

 closing our discussion in regard to increas- 

 ing the lifting capacities of the air-ship, 

 1 will say the point we have been discus- 

 sing is based on tbat all-important natural 

 law, that to get the greatest reaction with 

 a given power, we must have the greatest 

 area moving against the resisting mt- 

 dmm at the lowest velocity. 



A — Now Mr. B, while we have all the 

 advantages of your plans, we must not 

 over-look the fact that it is desirable 

 Btill to have the lightest possible motor 

 with the greatest power, to operate our 



-6- 



air-ships. Can you suggest the plan of 

 an engine which would be lighter than 

 those we now have? You understand 

 by increasing the dimensions of the parts 

 in the air-ships as you have suggested, 

 that they are necessarilv somewhat 

 bulky, which is not desirable, as there 

 is a greater surface to move against the 

 air during their flight. And securing a 

 greater power to a given weight of motor, 

 means either to decrease the dimensions 

 of the air ship, or carry a greater load. 



B— Yes Mr. A, there is plan by which 

 this can be accomplished. It consists in 

 working the steam at the lowest possible 

 pressure. We suppose we have a boiler 

 furnishing steam at a high pressure; 

 This high pressure calls for strong and 

 heavy parts upon which it exerts its pres- 

 sure. Suppose this boiler furnishes steam 

 at a pressure of one-tenth that of the 

 former. The reduction in pressure will 

 permit us to reduce the strength and 

 weight of the parts upon whicti the pres- 

 sure comes, to ont-tenth that of the 

 former. Yet this boiler gentrates an 

 many foot pounds of energy in * given 

 time as before, for the reason that this 

 depends on the heating surface. The 

 heating surface being as great as it was 

 before, it then comes to this: We have 

 reduced the weight of the boiler to one- 

 tenth that of its original and yet it gen- 

 erates as much energy in a given time 

 as before. But since we have reduced 

 the steam pressure, we will have to in- 

 crease the dimensions of the steam chest 

 to permit the low pressure to do mechan- 

 ical work as fast as it is generated. Yoa 

 understand we must have a greater pis- 

 ton area. The area must be increased 

 in proportion that the steam pressure 

 haf been reduced. 



A — Now Mr. B, how abont diminishing 

 the weight of the water in the boiler? 



B — Mr. A, i 1 case the water is contained 

 in the spact s among the Hues of the boiler, 

 the flues then should lie more closely to- 

 gether, thus giving less water space. It 

 would then require less water to till the 

 boiler and coyer all the heating surface. 

 The small amount of water then in the 

 boiler would be converted into steam and 

 pass out more quickly into the condenser, 

 to be returned by the injector. The result 

 would be, that the smaller amount of 

 water is used oyer more frequently in a 

 given time. It would probably be advis- 

 able to let the flues contain the water and 

 allow the heat to pass through the spaces 

 among them, for the reason that their 

 diameters being small, they will stand 

 the pressure with less thickness and 

 weight than in the case where a cylinder 

 of larger diameter surrounding the flues, 

 is required to stand the strain. This 

 cylinder will require great strength and 



