Evening star. [volume] (Washington, D.C.) 1854-1972, 1903-03-21
Boomerang Throwing.


"Boomerangs," said he, may be studied
for their anthropological interest as exam
pies of primitive art or for the manner in
which they illustrate dynamical principles.
But there is extraordinary fascination in
making and throwing them. and in watch
ing the remarkable and always graceful
curves described in their flight.
1.-The Australian weapons vary enor-
mously in shape and size, while the skill
of the natives in throwing them is great
in some districts and very small In others.
The marvellous flights that were described
by former travellers are but rarely seen
today and although 1t is undeniable that
many a native can make boomerang go
eighty meters away before returning to
his feet, I know OF only one Trustworthy
account of a much more sensational throw.
In this the boomerang described hve' cir
Giles in the air, travelling to distance or
about ninety meters from the thrower and
rising to a height of fOrty-fve meters.
Let us consider two types OF implements
The first Gig u is about so en-. in length.
measured along the curve, is bent Cat 81
almost to a right angle, and has the cross
section shown in fig. q 1t Is about 80 en-
wide and / en-. thick in the center at B,
and the dimensions Of the cross section
diminish slightly toward the ends of A and
c. The weight is about 23O grams. The
arms are twisted from the plane A B G
after the manner of the sails Of wind
mill, being rotated through or degrees
In the direction Of right-handed screw
about the lines A, B c, as axes. This
deviation from the plane Is subsequently
referred to as the twist and the peculiar
ity that, as seen in the cross section of fig.
2, one face is more rounded than the other,
is called the rounding.
"Boomerangs of the second type Zig 81
are about 70 en-. long and en-. wide, and
have a cross section similar to that of fig.
2. The twist is in the opposite direction,
involving a left-handed rotation of about .
degrees. The axes of rotation are now ID
E, E, instead Of E D, E F.
Returning Flights.
can implement of the first type is held
with the more rounded side to the left and
the concave edge forward. 1t is thrown,
with plane vertical, in a horizontal direc-
ton, and as much rotation as possible given
to it. The plane Of rotation does not re-
main parallel to its original direction, but
has an angular velocity "a about the direc-
ton of translation, and (2) about line in
its plane perpendicular to this.
1.-THE effect of co is that the path curls
to the left while owing to a. the plane of
rotation inclines over to the right q. e., ro-
tates in the direction of the hands of
clock facing the thrower), and it's inclina-
ton to the vertical becomes comparable
with 80 degrees in two seconds. The angu-
lar velocity (0 will now imply that the
path bends upward as well as horizontally
round to the left.
when the boomerang has described a
nearly complete circle it's pace has dimin-
ished, and it falls to the ground near the
thrower. (See figs. 4, 5, in which projec-
lions on a horizontal and on a vertical plane
are given. The direction of. the axis Of ro-
tation is indicated by giving the projections
of a line of constant length measured along
it. The scale of the diagrams I have drawn
is about LOGO.
THE angular velocity "a is increased by
an increase Of twist and by an increase of
rounding If it be desired that the boone
rang should describe a second circle in
front of the thrower Gigs. and y it must
be thrown much harder, SO that when one
circle has been described it may still have
sufficient forward velocity.
when the projectile has described the
first circle and is over the thrower's head