SUPERIORITY IN AN AIR-SHIP—RENARD. 153 
no necessity to analyze it in detail. We will simply remember that 
a rapid air-ship is necessarily stable. 
LY. 
From the foregoing the conclusion may be drawn that the different 
qualities which an air-ship may possess are not independent of each 
other but may be reduced to two fundamental properties, the indi- 
vidual velocity and the carrying capacity. The first of these quali- 
ties, the individual velocity, is highly desirable in itself, for without 
it dirigibility is impossible. Furthermore, it is the only means by 
which we can increase the absolute velocity, which is of such prac- 
tical importance. Finally, the absolute velocity is one of the factors 
determining the distance that can be covered in a single flight. When 
the individual velocity is increased, for the same reason both the 
absolute velocity and the distance covered are increased. If we also 
add the consideration that the possession of this speed necessarily 
implies the possession of stability in all directions, we must conclude 
- that in it we have a quality that is essentially fundamental. 
The carrying capacity of such a machine can be measured by the 
amount of weight of every kind which it can carry in excess of the 
weight of the air-ship proper, its motor, propellers, and all the parts 
indispensable to its operation. 
Given this weight it can be used in different ways. It can be 
employed in transporting a number of passengers or a considerable 
weight of merchandise. In the form of ballast it helps to attain the 
greatest altitude, and thus contributes to the duration of the aerial 
voyage. In the form of fuel supply it assures the duration of the 
voyage, thus affecting one. of the two factors entering into distance 
covered. 
Individual velocity can not be present in a high degree if the 
property of stability is not also present. This permits of the attain- 
ment of an absolute velocity which, coupled with duration of voyage, 
goes to make up distance traveled. The carrying capacity has no 
relation to stability. It can be utilized either for its own sake or 
to attain altitude, or to prolong the voyage and thus contribute in 
increasing the distance traveled. 
These different qualities may therefore be divided into two 
groups, those dependent on the individual velocity and those on 
the carrying capacity. As for the distance traveled, it is a common 
resultant of the two groups, for it is the product of absolute velocity 
by duration of flight, qualities belonging to the different groups. 
If we wish to obtain a synthetic idea of the value of an air-ship, 
it is by the ratio of the distances covered that their merit should 
be measured, but this quality is only the product of two others—the 
