NAVAL ARCHITECTURE TO AERONAUTICS. 297 
ment in this direction and I have heard very good arguments to foster a hope that 
the present form of air propeller may be supplanted by something radically different 
and more suited to our purposes. 
I differ slightly from the author of this excellent paper with respect to Langley’s 
comparison between longitudinal and transverse stability. I think Langley’s 
statement stands as a wonderful tribute to his analytical genius. At first I had the 
author’s idea of greater difficulty in maintaining transverse stability and I think 
it is a common tendency for beginners to regard a low center of gravity as desirable. 
I have noted that aviators on learning to fly are at first more concerned with the 
transverse than with the longitudinal control, very often to their discomfiture. 
It takes them some time to gain sufficient confidence to bank, or tip, the machine 
properly in making a turn. The tendency at first, especially with those using ail- 
erons, is to maintain the level in turning, thereby making a long tactical diameter 
and allowing the machine to slide off to leeward. But as soon as they get accus- 
tomed to the feeling of safety in banking during a turn and while running across the 
wind, they show an apparent contempt for transverse stability even to the point of 
recklessness, as is often seen during a spiral volplane, when the wings are sometimes 
tilted so as to appear nearly perpendicular to the earth’s surface. Nature seems 
to have provided for stability, or rather balance, by making a bird’s wing long 
transversely and narrow longitudinally, for, as forward motion is necessary to sus- 
tentation, the transverse balance is easily controlled at the wing tips. It would be 
the same with the stability of a ship having little or no transverse metacentric height 
if she were provided with a couple of long rigid levers projecting out from each side 
and a small hydroplane at the end of each lever. Such a device, however, would 
not serve to balance the ship any more than it does the bird when forward move- 
ment ceases. It is in this way that Mr. Curtis preserves the transverse balance of 
his hydro-aeroplane while on the surface of the water and for this reason also that he 
adds small air-chambers or pontoons to the small hydroplanes situated at the ends 
of the lower plane. 
But the longitudinal stability of an aeroplane, unlike that of the ship, is of 
paramount importance and is the chief concern of the experienced aviator, for by it 
and within a small range he has to maintain the efficiency of his angle of incidence. 
Aviators are therefore more concerned with the fear of deadening the flight, by chang- 
ing the angle of incidence enough to permit the machine to come down either ver- 
tically or tail first, than they are with coming down at a sharp angle either head first 
or sideways. 
I hope that many more naval architects will be able to devote sufficient time 
to aviation to follow Mr. McEntee’s example, and to still further illuminate the 
pages of these transactions next year with the principles of Naval architecture 
as applied to aviation. 
Nava Constructor McENTEE (Communicated) :—With regard to Captain 
Chambers’ remarks in connection with the relative importance of transverse and 
