The National tribune., 1905-12-21

~
THE DIAMOND SHOALS LIGHTHOUSE.
and men will enter these chambers and
assist the hydraulic dredging machinery
| by excavating with powerful water jets,
Shovels and special tools to force the
sand toward the central tube, where it
VIII be pumped upward and discharged
through the outside shell of the caisson
| by electors or sand pumps. If any solid
material, wreckage, for instance, should
| be encountered in the sand while sink
| ing, it is purposed to work it in toward
the central shaft. where it may be re-
| moved by graphing dredge. Smaller
distractions may be removed by divers
| through the airlocks provided for the
men.
| While the dredging is being done. the
work will be carried on as fast as posi-
| BILE in filling the different chambers with
concrete. The material, cement,
crushed stone, granite blocks, powders,
supplies. ETC., will be brought to the
caisson in lighters and taken aboard by
aid of the steam hosting engines and
stored in the different rooms until re-
quired. A balance will be preserved be-
tween the increasing weight Of the
| structure and the increasing buoyancy
of the surrounding water as the caisson
| sinks to it's final depth. The caisson
| may thus be held temporarily at about
| the same level to facilitate certain de-
made to sink more rapidly into the sand.
AS soon as the caisSon has been sunk
| to its proper depth, about % feet be-
low the surface of the sand, the bottom
being about so feet below the surface
! of the water, the work of filling will be
carried on, and rip-rap apron of ir-
regular granite blocks or powders will
be deposited on the surface of the sand
| entirely around the foundation, extend
| ing outward about Is feet from the cais-
| son. The stone will be brought in scows
or lighters. and may be placed directly
| by these lighters, or by the travelling
derricks or crane, from the gallery or
deck Of the caisson. The spaces within
| the large stones will be filled with small
ones and the smaller spaces will quickly
be filled with the drifting sands.
The Lighthouse.
| After having filled the entire shell of
| the caissOn with concrete, and having
| filled the central tube with wet sand, ex-
| cepting space for a cistern to hold 49,
| 900 gallons of fresh water, and for
rooms in which to store the oil, water
and hosting engine for the lighthouse,
the foundation will be complete and the
erection of the superstructure will be-
| gin.
The lighthouse will be of steel con-
| struction and will consist of an outside
steel shell with an inner central steel
| tube, to contain the spiral stairway
| chimneys and ventiiators, all of which
are well braced by steel Orders, frames
and partitions. The outer shell of this
structure is to be lined with layer of
about four inches of concrete or plaster
placed upon wire mesh or expanded
metal.
The lighthouse has eight different
floors, besides the lantern gallery and
watchroom. The first will be equipped
with three lifeboats, with a crane for
hnlSfinp lnWarin0 40 ct
The second floor is divided into four
rooms, and contains the fog signalling
apparatus and two oil engines. The
third floor will contain the hosting en-
CINE for operating the crane, two large
provision rooms and a bedroom. The
fourth and fifth floors each will have
two bedrooms, writing room and a
bathroom. One half of the sixth floor
will be devoted to the dining room, the
other half to the Kitchen pantry and re-
frigerator. The seventh floor will have
a double sitting room or library and
laundry. On this floor also will be
placed tank holding 1000 gallons of
fresh water The eighth floor will be
equipped for the lighthouse service
room. The ninth floor will contain the
watchroom, and will have a gallery ex-
tending all the way around it. The
floor above this will contain the light
itself, visible in storm or calm for about
20 miles.
The stability of this structure is ex-
pected to be greater than that of any
other steel structure hitherto built The
caisson Will rest upon a foundation of
sand and shell, pronounced by a COM
petent engineer, who has taken actual
behring's, to be Sin condition as able to
form the best foundation for any build
ing as the sand which forms the long
peninsula between the ocean and Pam
LEO Sound. upon which some of our
latest and heaviest masonry lighthouses
have been successfully built" The
! shape of the caisson is designed and the
weight of the entire structure is dis
ltributed so that when the caisson is
resting on its foundation the overturn-
ing force OF wind and wave, even in the
heaviest storm, will be less on the wind
ward side than the downward pressure
caused by the weight Of the structure.
Under these conditions IL will be i'm
possible for the lighthouse to be washed
. away or blown down.