Rock Island Argus. (Rock Island, Ill.) 1893-1920, 1912-12-06
The UNERRINC sun
1t Is Uncle Sans Most Reliable
Lighthouse Keeper.


lighthouse keepers. The sun or the
heat from it lights many hundreds Of
beacons along our coasts and water
ways evening after evening and ex-
tinguishes them punctually every morn
ing. They are guides on land and sea
that are never touched by human hands
from one months end to another. The
way in which the Unites States gov
eminent, through its lighthouse board,
has utilized the services of the sun and
made that great lamp Of heaven a
faithful and unerring servant is most
interesting.
The discovery Of acetylene gas was
the first step toward retiring the lonely
keepers of the little lights in faroff
places. Modern magic was not slow
In recognizing the fact that by the ap-
plication Of certain well known scien-
tific principles the lighting Of the great
chains Of beacons that girdle the coasts
of the two seas and the gulf and cover
the great lakes and every navigable
stream In our huge country could be
much simplifed.
The United States did not become in
terested in the acetylene light and its
automatically generating gas buoy until
about the year 1905 and did not adopt
it until 1908. Then the engineers of
the lighthouse board devised some
wonderful improvements, among them
the utilization Of the sun.
The self lighting and self extinguish-
ing acetylene beacon is a very simple
thing, but it depends almost entirely
on the sun valve" which is one of the
most wonderful but least complex Of
the achievements OF modern science.
In the first place, the source Of light
for these lone beacons is dissolved
acetylene, which is stored under pres
sure in steel cylinders. One of these
cylinders can be charged with enough
gas to last a small beacon three years.
Usually, however, In the case of float
ing buoys, a six months supply is all
| that is necessary, as such buoys are
overhauled and painted twice a year.
| Knowing the size of the fame and its
hourly consumption Of gas. it is very
easy to compute how long a cylinderful
| will last and how often it will need to
be visited. That is all the care the
! light will need. The sun valve does
the rest. a 81
TSe scientific principle upon which
the sun valve depends is that light
waves become transformed in different
degrees, according to the nature Of the
intercepting body. Sunlight upon dark
surfaces is converted into heat, and
heat produces expansion. This expan-
sion is especially perceptible In certain
metals.
In a carefully sealed and substantial
~ mounted glass jar nearly a foot
high and about one-fourth that in d.
ameter a thick black rod is placed per-
pendicularly through the center. 1t is
supported by three slenderer rods of
highly polished copper. The big black
rod is of copper also and is coated with
lampblack to make it absorb light to
the greatest possible degree. The sup
porting rods reflect light without abb
sorbing It and do not expand or con-
tract to the same extent as the largest
rod.
The thick black piece Of copper in
[
sitive to light and heat. As the sun
appears and the atmosphere grows
warmer in the morning this rod length
ems. 1t pushes down into the metal
chamber in which the glass jar rests
and touches the end of a lever. 1t
presses down on this lever, which is
controlled by a spring and cuts of the
flow of the GAS to the IamD
When the sun disappears from view
In the evening and the temperature of
the air falls the process is reversed,
The rod contracts and releases its pres
sure on the lever, allowing the gas to
flow upward to the lamp. The gas Is
ignited by a little pilot fame that is
never extinguished. Thus the beacon
is lighted at the proper time and is put
out when 1t is no longer needed, al
though along desolate coasts it may
never gladden. the human eye for
months at time.
The engineers of the lighthouse board
say that the precision of this device is
almost incredible. 1t can be used with
equal certainty In equatorial heat and
in polar cold, for it responds with the
utmost accuracy to small variations in
temperature. 1t is 1sed on lonely is
lands In the Pacific. There are nearly
q hundred of these sun valve beacons
In Alaska. In summer they are aids
to navigation, and In winter they guide
the travellers on dog sledges over the
frozen wastes.-Harper's Weekly.
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