New-York tribune. [volume] (New York [N.Y.]) 1866-1924, 1903-11-26
BELLS TETRAHEDRAL KITE.

The plan which Alexander Graham Bell has
in mind for solving the problem Of aerial naVi-
CATION was described by him q few weeks ago
in THE National Geographic Magazine" That
account is now supplemented in the pages of
THE Popular Science Monthly" with further
details by Gilbert II. Grosvenor. Although
much work yet remains to be done before the
demonstration can be considered complete and
satisfactory the additional details which are
now supplied strengthen the favorable impress
sion made by Professor Bells earlier expert
ments and his theories.
For lifting power Professor Bell relies upon
a kite of his own design Until recently the
most efficient instrument Of that kind was the
one designed by Hargrave. This was known as
the box kite, and has been highly serviceable
to meteorologists in sounding the upper air 1t
has been pointed out, however, by Professor
Newcomb that that model is unavailable for
flying machine. 1t viii carry light loads. but
is unsuited TO heavy ones, matter how great
the enlargement. The difficulty is that the
weight increases with size much more rapidly
than does buoyancy. The bigger the kite, then,
the more useless it becomes relatively. By
adopting a cell OF an entirely different form it
is made possible to multiply dimensions almost
indefinitely and to secure proportionate gain
in efficiency. That much the public knew late
last summer in general way, but Mr.. Grosve-
nor is now able to give striking illustration
Of the fact. With box kite, or even a series
of them flown tandem, it has rarely been prac-
tea BILE TO raise the string to a greater angle
with sea level than 40 or 90 degrees. The
tetrahedral kite lifts it up almost straight, its
angle with n horizontal line usually amounting
to so degrees Moreover, the Bell kite is said
to preserve its equilibrium to a remarkable de-
gree in squalls-certainly a valuable trait if
anything is ever done with it.
In at least one particular the tests with the
new design have gone further than those Of the
Langley machine. From the beginning of his
experiments the inventor Of the latter has had
misgvngs about the operation of launching
Nearly all of his models disappointed him at
that stage of his experiments, and the failure Of
his full grown airship a month or two ago was
officially attributed to some fault of the device
which was to give it start Now, while Pro
fessor Bell did not imperil any ones life or
soundness of limb, he has managed TO send up
q kite that was capable OF sustaining the COM
bined weight of q man and an engine. The
fabric was first made TO rest upright upon three
light boats, parallel with each other, and the
latter were secured to the former so as to con-
stitute parts Of the airship. 1t was then an
easy matter to set the thing afOat on the sur
face of the water; and when a steamer, taking
It in tow, acquired a speed of twelve or fifteen
miles hour, up went the kite steadily and
gracefully. Wheels, running on land, might
have been substituted for the boats, and per-
haps these will prove more convenient when
propulsion is effected by screws thrustipg
against the air behind instead of towing. How
ever, Professor Bell has already recorded at
least one successful launch Of a large craft.
In outward appearance the tetrahedral kite
is unlike the four-winged machine designed by
the Secretary of the Smithsonian Institution
and that invented by Sir Hiram Maxim, but
they all work on the same principle. They
utilize the aeroplane for lifting purposes. The
differences are only those Of form. Thus far
the gas bag type, of which the airship of Santos
Dumont is the most familiar representative
seems to have shown greater popularity and TO
have yielded better results. It's devotees in
cude at least few men who are trained engi-
neers. though none of them. perhaps are so
distinguished by other scientific service as Bell
Langley and Maxim. When competition be-
tween the two systems has been carried further
perhaps there viii be different story to tell
The developments of the next twelve months
viii certainly be watched with unusual interest