discussing applies to all. 



A— Then Mr. B, You mean to say this 

 law applies to all air-ships, such as those 

 using horizontal screws, aeroplanes etc.? 



B — Yes Mr. A, it applies to all, inde- 

 pendent of their form. You understand 

 Mr, A, that in the case of propellers 

 moving against this yieldina medium, 

 —the atmosphere, our object is to secure 

 a foothold ; and if this foothold yields in 

 the least, under the pressure of the pro- 

 peller, it means just that much dead loss 

 in the ener^jy of the motor. The larger 

 then the surface of the propeller, moving 

 against this yielding medium, the better 

 is the foothold, and the less the loss uf 

 power. In order that there be no loss of 

 power, the area of the propeller must be 

 brought to such great dimensions, giving 

 such a great foothold on the air, that 

 it will not yield at all from the pressure 

 of the propeller. But these dsmensiuns 

 C8n never be reached, either in practice 

 or theory. The practical dimensions 

 which may be rtached, can only be de- 

 termined by experiment, tio we may 

 conclude without a doubt, that in all 

 air-ships of the coming future, at best, 

 we will always have a heavy and unavoid- 

 able loss of energy from this source. 



A — Mr. B, in regard to a revolving 

 horizontal screw, 1 suppose you mean to 

 crowd the air vertically downward, thus 

 gaining the reaction to lift the ship. 



B — Yes Mr. A, that is the idea. 



A — Mr, B, suppose I had an air-ship on 

 this plan, what change would 1 have to 

 make, to double its lifting capacity, 

 without increasing the power of the sus- 

 taining motor? 



B~You would have to multiply the 

 area of the blades of the screw to eight fold. 



A— Mr. B, 1 would like to a^k you th« 

 same question in regard to the air ship 

 with aeroplanes. 



B — Mr. A, suppose in the cases 1 am 

 about to explain, that the air-ships daring 

 their flights are to remain at a constant 

 elevation, and in all cases to move at the 

 .same rate, and exactly horizontally. Now 

 Mr. A, you may double the lifting capac- 

 ity of the ship by multiplying the area 

 of the aeroplane to eight fold, and fixing 

 it at such an incline from a horizontal 

 position, that it will crowd the air down- 

 ward from its under surface at one-half 

 that of the former rate. In this case 

 the area of the blades of the screw which 

 propells the ship, do not have to be 

 modified. And there is another way 

 Mr. A, in which you can double the 

 lifting capacity of your ship without 

 increasing the power of the sustaining 

 motor. It is accomplished by doubling 

 the area of the aeroplane and letting it 

 remain at its former incline. And then 

 multiplying the areas of the blades of 



-4- 



the screw to eightfold. 



A — Mr. B, in regard to modifying the 

 area and incline of the aeroplane, and 

 areas of the blades of the screw, in order 

 to double the lifting capacity of the ship 

 without iucreasing the power of the sus- 

 taining motor, I want you to explain 

 this: Why are these particular changes 

 necessary to bring ab. mt this result? 



B — Mr. A, They are in harmony with 

 the law pointed out in the case of the il- 

 lustrative air-ship, where the fact was 

 shown we might by multiplying the area of 

 a plane to eight fold, and allowing it-i sur- 

 face to moye against the air, either directly 

 or indirectly at one-half its former rate, 

 double the lifting capacity of the air-sqip. 

 Now in regard to the ship with the af-ro- 

 plane; You multiijlifd ihe area of the 

 aeru[)lane to eight told, and fixed it at such 

 an incline that itwould crowd the air down 

 at only one-half the former rate. The aero- 

 plane now descends in the yielding air at 

 only one -half its former rate. And at the 

 same time it is gliding upward, I might 

 say at one-half the former rate, thus re- 

 maining at a constant elevation. The aero- 

 plane now, does not have to be pushed up 

 so steep an incline as before. With its load 

 it has only to be glided upward in the air 

 half so liigh in a giyen time, and decends 

 only half so far in that time. For this 

 reason it will sustain double the load with 

 the former power, and in regard to the sec- 

 ond case of modifying the aeroplane, you 

 double its area and lift it at its former 

 incline. This doubled area calls tor double 

 the horizontal pressure, to move the ship 

 at its former rate carrying double the load, 

 because of the incline of the aeroplane not 

 having been changed, and was compelled 

 to glide upward in the air at as steep an 

 angle as before any modifications were 

 made and at the former rate. Or we can 

 ilkistrate the case equally clare by saying, 

 the aeroplane crowded the air downward, 

 and this doubled horizontal pressure was 

 then secured by multiplying the area of 

 the blades of the screw to eight fold. 

 Now the explanation of the modified 

 areas etc., of the screw blades of the air- 

 ship using horizontal screws, explains the 

 philosophy of those on the ships using 

 aeroplanes. The revolving horizontal 

 screws crowd the air downward practi- 

 cally the same as the plane in the case of 

 the illustrative air-ship, as do the aero- 

 planes, for the inclined blades of the 

 screw are only aeroplanes moving in a 

 circular path ; and in the case of the 

 illustrative air-.<«hip. it was shown that 

 when the area of the plane was multiplied 

 to eight fold, we could lift double the 

 weight without increasing the power, 

 for the same reason we can do so in this 

 case. Accrding to fundamental principles 

 we are not confined to any particular 



