Evening star. [volume] (Washington, D.C.) 1854-1972, 1907-06-02

their corners they compose a structure Of
remarkable rigidity, even when made of
light and fragile material, the whole struc-
ture possessing the same properties of
| strength and lightness inherent in the in
| dividual cells themselves.
1.-THE unit tetrahedral cell yields the
| skeleton form of solid. and 1t is bounded
by four equal triangular faces. BY cover
Ing two adjoining faces with silk or other
| material suitable for in kites. we ar
rive at the unit winged cell'' of the COM
pound kite. the two triangular surfaces
in their flying position resembling a pair
of wings raised with their points upward,
the surfaces forming a dihedral angle.
-Four of these unit cells, connected to-
gether at their corners. form a four-celled
structure having itself the form of tet-
rahedron containing in the middle an
empty space of octahedral form equal in
volume to the four tetrahedral cells them
selves.
Kites so formed exhibit remarkable
stability in the air under varying condi-
tons of wind, and 1 stated in my paper
that the kites which had the largest CEN
trail spaces seemed to be the most sta
Bile in the air. OF course, these were the
structures that were composed of the larg-
est number of unit cells. and I now have
reason to believe that the automatic sta
bilty of these kites depends more upon
the number of unit cells than upon the
presence Of large empty spaces in the
kites, for 1 have found, upon filling in
these empty spaces with unit cells, that
the flying qualities of large kite have
been greatly improved. The structure, 50
modified. seems to fly in as light breeze
as before. but with greatly increased lift
Of
strength is enormous.
II had hitherto supposed that If cells
were placed directly behind one another
without providing large spaces between
them comparable to the space between
the two cells Of Hargrave box kite, the
front cells would shield the others from
the action Of the wind, and thus cause
them to lose their efficiency, but no very
marked effect Of this kind has been OBJ
served In practice. Whatever theoretical
interferences there may be, the detrimental
effect upon the flying qualities of kite
are not, practically, obvious. while the
gain in structural strength and in lifting
power outweigh any disadvantages that
may exist. 1 presume that there must b.
some limit to the number of cells that can
be placed in close proximity to one
other without detrimental effect. but so
ITO test the matter, l put together into
one structure all the available winged cells
| had in the laboratory-1.300 in number
These were closely attached together with
out any other empty spaces In the struc-
ture than those existing between the indi-
vidual cells themselves when in contact at
their corners.
The resulting kite, known The Frost
King pages Is and 16j, consisted of sue
cessive layers or strata of cells closely
superposed upon one another. The lowest
layer, or floor of the structure. consisted of
IL rows of 13 cells each The cells forming
each row were placed side by side. attached
to one another by their upper corners. and
the IL rows We're placed one behind the
other. the rear corners Of one row being at
tached to the front corners of the row i'm
mediately behind. The next stratum above
the floor had IL rows of IA cells; the next.
10 rows of Is cells, etc. each successive
layer increasing in lateral dimensions and
diminishing in the fore-and-aft direction,