Evening star., 1926-08-15

and fog signals is in the hands of the
Lighthouse Service, and the Coast and
Geodetic Survey maps the work OF
those two by means of it's charts
which indicate the condition of the
river.
These charts are beautiful pieces OF
work. They show in detail the char
acter of the river bottom and the
topography of the shore line. Aids
70 navigation, such as lighthouses and
buoys, and dangers. such as shoals
ana breakwaterS. are also clearly
shown. Four charts are issued cover
Ing the Potomac River from Wash
tngton to its mouth.
The constant improvements in the
local water front, changes in the chan
mel and alterations In the positions of
lights or buOyS are Immediately re-
ported to the Coast and Geodetic Sur
vey and incorporated in their charts.
The survey sells it's river maps at
cost price and encourages the use.
especially by amateur pilots. of up-to-
date ones. for the loss of numerous
vessels is believed to have been caused
by relia nee upon Old charts.
Information OF Importance needed
by mariners cannot all be shown on
charts. and for this reason the survey
supplements them with a publication
known as the Coast Pilot. Annual
tide tables also are issued for the
benefit of those who wish to steer as
scientifically as possible.
With the construction of every road
must go the installation of an ade-
uuate system of sign posts and danger
signals, and the same applies to a
river road. Long before the Po-
tomac was properly channeled 1t was
equipped with a network Of aids to
navigation in the form OF buoyS,
lights and fog signals for the benefit
of those who travelled upon it, All
came under the jurisdiction of the
United States Lighthouse Service,
which maintained them with a Singu-
lar record of efficiency, and kept them
abreast of all modern improvements.
There has always been an element
Of romance and adventure attached to
lighthouses. The spectacle of a light
in the darkened distance, blazing
forth warning of danger has ap
pealed to mans poetic instincts. The
Potomac has II lighthouses in the 110
miles between its mouth and Wash
ington, while in the same distance
there are l6 minor lights, less spec
tacular In their operation. being un-
attended. but equally important pro
pOrtionately to the rivermen. whose
safety depends so largely upon their
proper functioning.
!: x
John s. CONWAY, deputy commits
sioner of lighthouses. explained
something of the nature of the lights
on the Potomac.
I'm the case of attended lights" he
said, where resident Keepers are EN-
ployed-which are generally regarded
by the public as lighthouses proper
there are several types on the local
INlp
Cf which may be seen on Blackstone
Island, consists of a combined tower
and dwelling of timber or brick con-
struction. Another kind of lighthouse
frequently encountered on the Poto-
mac employs pile foundation to sup
port a dwelling over a submerged site.
Maryland Point has light of this
sort
The oldest lighthouse still in use on
the Potomac is at Upper Cedar Point,
this station having been put into
operation in 1921 The Lighthouse
Service itself is older than our Gov
ernment It's history dates back to
l116. when Boston Light, the first on
this continent. was built by the prov
ince of Massachusetts at the entrance
to Boston Harbor Several other
lighthouses were built while the Colo
MES were still loyal to Great Britain.
and by the time an independent GOV
ernmcnt had been established 10 were
in operation. all of which were ceded
To the National Government by the
individual States. that they might
render more efficient service under
Federal supervision. Their mainte-
nance was placed under the Treasury
Department until 1903, when the
Lighthouse Service was transferred TO
the Department of commerce. On
I,,I,- EllrP1Il
lighthouses was established.
Speaking OF the illumlnant en-
ployed by the various lights, Mr.. Con-
way said that since 1875 kerosene
has been the principal one in use.
THE incadescent oil vapOr lamp" he
continued which is now generally
employed for important lights. burns
vaporized kerosene under an incan-
descent mantle. giving powerful
light The kerosene is stored in a
tank and is forced by compressed
air, produced by hand pump, into
the vaporizer lamp. The air pressure
decreases so slowly during the oper-
alton of the light that only few
strokes of the pump once or twice Il
night are necessary
Increased efficiency is given by
means of an automatic thermoStat
alarm. n device which summons the
attendant by the ringing of an cleo
trio bell when the light is not burn
ing properly. either too high or too
low Smith Point Light or the
south side Of the mouth of the Po-
tomac. is equipped in this fashion,
and gives a light that is visible Is
miles
Various other illuminants now
used by the service can be seen on
the Potomac. Oil gas is burned at
many lights along the river, includ-
ing Piney Point and Blackstone Is
land. Electric inCandeScent lights
are used at the Fort Washington
light station and several other hghts
near the Capital City.
I'm addition to the light tower, oil
house, keepers dwelling, workshop
and landing wharf" resumed Mr..
Conway. "a completely equipped
light station includes an efficient fog
signal The first fog signal in the
United States was cannon IN
stalled at Boston Light in 1719. which
was fired when necessary To answer
the signals OF ships in thick weather.
Guns of various types were used at
other lighthouses, but have now
been abandoned.
Bells were introduced at an early
date and are still extensively used.
Thirteen of the light stations along
the Potomac are equipped with bell
fog signals. and another. Smith
Point Light Station. has an air dia-
phone for this purpose. with a bell
for emergency use in case the dla-
phone becomes disabled.
The diaphone is powerful m
strument operated by compressed air.
and giving a sound similar to that
produced by a siren. but with an
abrupt grunt at the end of the note
which adds to its effectiveness.
practically all fog signals. as now
installed. sare provided with govern