Evening star. [volume] (Washington, D.C.) 1854-1972, 1927-06-29
EARTH COMPASS
USED ON FLIGHTS
Maitland and Byrd Guided by
Same instrument That
Aided Lindbergh.

The fight from California to the
Hawaiian Islands involves a most 1if-
| ficult piece of navigation.
Flights to Europe are relatively
| easy. compared with those to Hawaii.
| All the aviator has to do is to fly east
| ward and he will be sure to hit some
part of Europe. If Ireland is missed
| there Is always France farther on.
In the Pacific Ocean it is different.
The aviator has to fly for nearly 2.400
miles and hit a line of islands only
| 317 miles long. If he goes bit too
| far north or south he will not merely
reach another part of the coast. IN.
stead he will miss the islands en-.
tirely. perhaps without knowing it.,
and fly on until his gas is exhausted.
And by that time he may be far away
| from steamer lanes.
But the same instrument that guild.
ed Lindbergh to the Irish coast, en-
tirely by dead reckoning and without
a single observation of a celestial or
terrestrial guidepost, helps the Pa
| cif1c flyers. This is the earth in
ductor compass, the product of genius
| in the United States Bureau of Stand
ards. 1t is also the chief navigational
| instrument of Comdr. Byrd's America.
Principle Like Dynamo.
Like the familiar magnetic compass
the earth inductor compass depends
on the fact that the earth is a great
magnet. 1t also depends upon the
principle of the electric dynamo: Spin
ming coil of wire in a magnetic field
| produces current of electricity in
| the coil
| In the dynamo there is what is
/ called field magnet TO produce the
magnetic field which surrounds the
moving coils or armature. In the
earth inductor compass the earth it.
self acts as the field magnet. The
armature consists of four coils of
wire, wound to form a cross. 1t is
spun as the plane goes through the
air by means of four-cupped wind
mill.
AS the coils revclve they touch
| brushes which pick up the current
generated. When the coils touch the
brushes while they are in an east
and west direction, there is no cur
rent. The wires of the coil are then
moving in the direction of the lines of
force of the earth. In order to have
current, the wires must cross the
lines Of force. However, If the coils
are north and south, or in any other
direction than east land west, a cur
rent does flow. Then a delicate gal
vanometer on the planes instrument
board shows the deviation from the
course.
Pilot Sets Controllers.
To use the compass, the brushes
may be set so that they are in an
east and west direction, when the
plane is flying north, for example. The
galvanometer will tell the pilot if he
departs from a northerly direction. If
he wants to fly in another direction,
the pilot can set controller dial.
Then the galvanometer will indicate
zero when he is flying in the direc-
ton for which the control dial has
been set. If he starts in the wrong
direction, he merely has to turn the
plane slightly, and the galvanometer
needle will again indicate zero.
The chief advantage of the earth In
ductor over the old form of compass
is that it can be read at a distance.
The inductor mechanism is set in the
tail of the machine, far from the elec-
trical coils and steel of the engine and
other machiner. that would affect the
| compass needle. Also, the motion of
the plane as 1t banks on one side or
the other does not disturb it, as 1t
would freely swinging needle.
Byrd Used Sun Compass.
The sun compass which Comdr.
Byrd used on his polar flight is
especially adapted for use in the Arc
tic, because there the magnetic pole
Is south of the flyer. A magnetic
compass, whether earth inductor or
not, would indicate any direction but
north. Every Boy Scout is familiar
with the principle of the sun compass.
for he can use it 10 find the north
with a watch.
Point the hour hand Of your watch
to the sun. Then south is halfway
between the hour hand and the figure
II. If the watch were of a kind used
in European countries, with 24-hour
dial, it would be simpler. Then you
would merely need to point the hour
hand to the sun, and the figure "a
would point to the south. In effect,
the sun compass is such a 24-hour
watch