LANGLEY AEROPLANE—ZAHM. 219 
its propellers whirring and its pilot supplementing, with manual con- 
trol, if need be, the automatic stability of the machine. This method 
of launching, as shown by subsequent experimentalists, is a practical 
one and was favorably entertained by Mr. Curtiss. He also thought 
of starting from the ground with wheels, from the ice with skates, 
from the water with floats. Having at hand neither a first rate 
smooth field nor a sheet of ice, he chose to start from the water. 
In the accompanying illustrations, plates 1 and 2 show the appear- 
ance of the Langley flymg machine after Mr. Curtiss had provided it 
with hydroaeroplane floats and their connecting truss work. The 
steel main frame, the wings, the rudders, the engine and propellers 
all were substantially as they had been in 1903. The pilot had the 
same seat under the main frame, and the same general system of 
control as in 1903. He could raise or lower the craft by moving the 
big rear rudder up and down; he could steer right and left by turning 
the vertical rudder. He had no ailerons nor wing-warping mecha- 
nism, but for lateral balance depended upon the dihedral angle of the 
wings and upon suitable movements of his weight or of the vertical 
rudder. And here it may be noted that Langley had placed the ver- 
tical steering rudder under and to the rear of the center of gravity. 
So placed, it served as a fairly good aileron by exerting a turning 
movement about the longitudinal axis of the machine. 
After the adjustments for actual flight had been made in the Cur- 
tiss factory, according to the minute descriptions contained in the 
Langley Memoir on Mechanical Flight, the aeroplane was taken to 
the shore of Lake Keuka, beside the Curtiss hangars, and assembled 
for launching. On a clear morning (May 28), and in a mild breeze, 
the craft was lifted onto the water by a dozen men and set going, with 
Mr. Curtiss at the steering wheel, ensconced in the little boat-shaped 
car under the forward part of the frame. Many eager witnesses and 
camera men were at hand, on shore and in boats. The four-winged 
craft, pomted somewhat across the wind, went skimming over the 
wavelets, then automatically headed into the wind, rose in level 
poise, soared gracefully for 150 feet, and landed softly on the water 
near the shore. Mr. Curtiss asserted that he could have flown far- 
ther, but, beg unused to the machine, imagined the left wings had 
more resistance than the right. The truth is that the aeroplane was 
perfectly balanced in wing resistance, but turned on, the water like a 
weather vane owing to the lateral pressure on its big rear rudder. 
Hence in future experiments this rudder was made turnable about a 
vertical axis, as well as about the horizontal axis used by Langley. 
Henceforth the little vertical rudder under the frame was kept fixed 
and inactive. 
After a few more flights with the Langley aeroplane, kept as nearly 
as possible in its original condition, its engine and twin propellers 
were replaced by a Curtiss 80-horse motor and direct-connected 
