Yorktown Lightship Lens
Virginia
Harbour Lights #675
Until the invention of the refracted lens
by French physicist Augustin Fresnel in 1822, illumination for lighthouses
and vessels was dependent on lanterns and lamps with rudimentary
reflectors. Ironically, it was at almost the same time that the "first
outside vessel was placed off the coast of the United States," in
Chesapeake Bay, off Craney Island, at the entrance to the Elizabeth River.
The light to warn mariners was suspended
from the top of the mast, and either required that a seaman climb the mast
to keep the oil filled and re-light wind-extinguished flames, or the
lantern had to be raised and lowered by ropes. Needless to say, this was
an important and tiresome task for the lightship crew.
While the hazards of serving as a
lighthouse keeper was harrowing for most, imagine the dangerous life of
sailors serving on a lightship. Quarters were cramped, tours were long,
and the duty was anything but safe. One sailor described a lightship as
being similar to a barrel - continuously rolling and in motion. Sitting in
open waters to protect incoming vessels from accidents, the lightship was
in constant danger of the same fate.
As technology advanced, it was the
addition of electricity to illuminate the lens that made the difference
for the lightship. In 1913 the first lightship was outfitted with "one
parabolic silvered reflector mounted on a compound pendulum and revolved
by an electrical motor to show a flash every 10 seconds" using storage
batteries to generate the current. In 1934, the Lighthouse service
equipped a lightship for remote control by radio of all facilities,
including light, fog signal and radio beacon, opening the door for
complete automation.
With the installation of the Fresnel lens,
lighthouses were able to cast their beacons to far greater distances, but
placing these weighty lens systems on a lightship was not an easy task.
Even the smallest of the lens - Fifth and Sixth Order - were difficult to
mount and maintain and had to be specially designed. In 1937, a 375mm
duplex lantern was designed for use on a single-mast vessel.
Between 1820 and 1983, 116 lightship
stations were established. The peak was reached in 1909, when 56
lightships were in service; but by 1939 when the Coast Guard assumed
responsibility for aids to navigation, the number was down to 30.
Illuminated buoys, using technology not even imagined by the long ago
lightship crews, now safely mark waterway approaches. In 1983, the
Nantucket Shoals Lightship was replaced with a large navigational buoy,
and the era of the lightship was ended forever.
This lens, and examples of all manner of
lens, lamps and lanterns, along with other navigational tools, can be seen
at the Coast Guard Training Facility Aids to Navigation Department at
Yorktown, Virginia. Located on the first deck of Canfield Hall, the
exhibit is open to the public. For more information call (757) 856-2271.
|
HL# |
Name |
MSRP |
Introduced |
Retired |
Edition |
|
675 |
Yorktown Lightship Lens |
$110 |
1/05 |
|
4,000 |
|
