Eagle River review. [volume] (Eagle River, Wis.) 1890-1927, 1896-12-17

speak covering about one-quarter of
the core on either side. A clear idea of
the way this should be done can be had
from the picture of the armature.
Enough layers should be wound to make
the punches project from the core about
n fifth of an inch. When the last layer
is on, the free end of the wire should be
brought to the same end of the armature
core as the wire underneath.
After this was done John took strip
of cotton batting and wrapped it twice
around the long end of the armature
shaft, close to the core in such a way as
to bind the under wire to the shaft.
Then he bound strip of thin sheet cop
per. one-Quarter of an inch wide around
the cotton, making a small hole in the
was passed and fastened. Then he re-
peated the cotton winding and copper
binding operation at a point quarter
of an inch nearer the end of the shaft,
fastening the free wire. exactly as he
had done With the other wire and cop
per. The copper was bought for few
cents from an electrical supply store,
the same as the wire had been, and when
that was done the armature was all
ready to be put in place. Having at
tended to that. John took small spool
on which silk had been wound and
projected from the frame. This SPOOL
was later to serve as the pulley by
which the shaft was revolved.
The dynamo was then completed by
cutting two strips of thin sheet copper
one and a quarter inches long and
quarter of an inch wide. and inserting
them through the oblony holes that had
been made in one of the projecting
arms of the frame, in such a way that
the free ends of the copper rested on
the copper bands outside the cotton bat
ting that was wound on the shaft. These
fat pieces of copper answered to the
'brushes'' and the copper bands to the
"excters' of a regulation dynamo. When
the armature which, after being wound
is just large enough to Craze the upper
and lower parts of the magnet is rapidly
revolved, Il current of electricity. is gen
Grated and conveyed through the wire
and excters to the brushes. If Il short
piece of wire wer made to connect the
ends of the brushes that project through
the arm. this current of electricity would
pass from the armature to one brush
through the wire and directly back to the
other brush and thence to the armature
again. thus forming q complete circuit.
travel fartehr, and if: before it returns
to the dynamo, it is passed through a
lamp. the lamp will glow. and that is the
way all electric lighting is done. Johns
dynamo would not furnish enough cur
rent to light even an ordinary sixteen
enough of it to make one. of the little
''pca lamps" which John bought at an
electrical supply store for so cents, glow
with dazzling brightness. In the picture
John is shown holding this little lamp
in his hand
When he first started the dynamo to
running, he got his power from the big
wheel of his mothers sewing machine.
and his younger brother sat and worked
the pedals for him. OF course, the fas-
ter he made the wheel fly. the more
electricity was got from the dynamo. and
the wheel of the sewing machine had to
he worked very fast in order to make
the lamp glow. This dynamo made what
is known as an alternating current-that
is the current was produced only when
the two lunches of wire passed the mag
net For this reason when the reVolu-
tons were slow, the lamp would glow for
an instant and then be dark for an in
slant. but when the armaturc was made
fairly to buzz the glow would be steady.
1t was not easy TO keep up the power
wanted very long by thu use Of the sew
ing machine wheel and it was not very
clockwork with heavy weight. which,
when wound, would run the dynamo for
a long time. He had an interesting ex-
pcrence very soon after his little ma
chine was completed. He forgot that
electricity always seeks the easiest road
and he held the two wires in his hand IN
such a way as to receive the current
through his body. OF course, it was
not strong enough to iaiure him, but II
startled him and made him understand
better than he ever did before how the
accidents happen around dynamos, 50
often reported in the newspapers. Ii
John had placed small motor so tina t
the current would pass through it as it
did through the little pea lamp, the motor
would have whirlcd exactly rs large
motors connected with large dynamos do.
And as q matter of fact, John did aft
erward construct small motor under the
direction of his electrical friend, and
found it much simpler task than the
making of the dynamo itself.
From the Crows Nest.
On December c, writes c. e. Rorch-
grewinck the antarctic explorer, in the
Century, I sighted the edge of the ice
pack from the crows nest and shot my
first seal. which was of the white kind,
it's skin being injured by several deep
scratches 1t was Geld up in the white
cask on the maintop that morning. Be-
fore us were the icefields. with the strong
ice blink in the air above us. and as we
drew near to the edge the snow white
petrels became more and more numerous.
They are of the size of an ordinary
pigeon, but much more graceful. Their
large eyes are deep black, as are also
their bold, curved beak and their elegant
webbed feet. They seemed almost trans
parent as with spread. quiet wings they
scared in the air about the crows nest
where | was hanging on to one end of a
large telescope. heavy enough to lift me
e. IL r. -