875 
the present has not been applied with 
success except what has been attempted 
with gliding boats. In these boats, how- 
ever, the hull does not leave the water, 
but skims on the surface, which hinders 
the attainment of really high speeds. 
“The most important characteristic of 
the hydroplane is that the resistance of 
the water is not dependent on the speed, 
but remains constant, and is equal to 
half the total weight ‘of the apparatus ; 
the total resistance is increased only by 
a portion of resistance due to the air, a 
portion naturally proportional to the 
square of the speed. In consequence, 
similar hydroplanes in the future should 
be able to attain speeds of 60 to 100 
miles an hour and change themselves 
into flying machines by the addition of 
the necessary planes for aérial suspen- 
sion.” 
After six years of experimenting, 
Forlanini can now consider that he has 
arrived at fully satisfactory and definite 
results, says the. Scientific American. 
The first hydroplane he tried, during 
the years 1905 and 1907, immediately 
demonstrated the excellence of the new 
system, but its performances were al- 
ways handicapped by the irregular work- 
ing of a bad 70-horsepower motor with 
which it was fitted. Another hydroplane, 
tried during the years 1908 and 1909, 
was fitted with a steam motor that 
worked more regularly. Although the 
effective power was only 25 horsepower 
and the weight of the boat over a ton, 
this machine attained a spect of over 50 
kilometers an hour. : 
The hydroplane that-is Dcne tested at 
present weighs two tons. when there are 
two persons aboard=+ possible to 
carry four other persons bait is fitted 
with a 100-horsepower gasolene motor. 
It has attained a speed of 45 miles an 
hour, and this speed will be increased 
by the introduction of a few modifica- 
tions that are being gradually indicated 
during the trials it is now undergoing. 
This hydroplane has a hull 32.8 feet 
long; at the bows and stern are two 
strong steel tubes transversely. At the 
THE NATIONAL GEOGRAPHIC MAGAZINE 
four free ends of these tubes—namely, 
on the starboard and port sides of the 
boat—is fixed a sort of framework, 
which contains a series of planes, one 
above the other. These superfices of 
planes are made of high-resistance steel, 
the workmanship being very accurate, 
_and their size decreases from the top to 
the bottom. 
When the hydroplane is not working, 
but is floating on the water like any other 
ordinary boat, the planes are immersed 
in the water, and have a slight horizontal 
inclination. As soon as the hydroplane, 
owing to the working of the screw, be- 
gins to move forward, the water exer- 
cises a vertical force on the planes in 
precisely the same manner as the air on 
the planes of an aéroplane. The hull 
therefore tends to rise and so diminish 
its immersion and, naturally, the resist- 
ance against its motion in a manner that 
the speed is able to increase. 
In this way there comes a moment 
when the hull is completely out of the 
water. At this point the speed rapidly 
increases, and little by little the various 
planes or superfices rise out of the water 
one after the other. When the maximum 
speed is reached only the bottom planes 
remain on the water, while the bottom 
of the hull is 65 centimeters higher. 
The propeller by which this strange 
craft is driven is carried on a hollow fin, 
which may be seen amidships, the short 
propeller shaft being revolved by bevel 
gears attached to a vertical intermediate 
shaft, driven direct off the motor. 
IMPORTANT CORRECTION 
N page 603 of the July, 1911, issue 
the credit line under the illustration 
of the diplodocus was erroneously given 
as “the late” Charles R. Knight. Mr. 
Knight, the well-known artist-naturalist, 
whose paintings and models of birds, 
animals, and fossil creatures for the 
United States government, the Carnegie 
Institute, and the American Museum of 
Natural History have distinguished him 
in his profession, resides at Lawrence 
Park, Bronxville, N. Y. 
