Year: 1873

the guidance of Captain Clinton B.
Sears, of the L. S. Engineer Corps,
the officer i'm charge, | walked over
every foot of the breakwater thus far
constructed and boated along the
course of the rest of it. From The in
ner end starting from and resting upon
the southwest corner Of Rattlesnake
Island it runs southerly to the north
western corner Of Dead Mans Island.
The length of the breakwater is $500
feet; its outline is that of long and
gradual curve, an are of an immense
circle, convex toward the south from
which come the heaviest winds
and surfs which it will have to with
stand.


The material is Oregon fir, heavy
iron bands and rods and huge broken
bOulders of rock. This is what art
furnishes, but as fast as art builds out
the breakwater nature completes its
strength by washing in thousands of
tons of sand against the windward or
tideward side.


This deposition has already formed
broad banks extending several hun
dred feet outward from the shore end
and backing up 50 far to the windward
as to present surface of some score
of a1res already. Fhus nature prompt
ly supplies human effort with a broad
and deep sand bulwark much wider
than that which separates San Diego
bay from the open sea, and which
must become permanently established
long before the remarkably strong ar
tificial work of the original breakwa-
ter can decay or fail.


The work is very strongly done.
Teey drive heavy timbers thirty feet
long and one foot square set closely to-
gether side by side. Inside of this
second row of thick plank twelve inch
es by four is driven so as to break
joints. This double timbering rises
four feet above high water. Just be-
low the top, both inside. and out, heavy
stringers are thickly bolted along the
entire length. This makes barrier
or bulkhead practically water tight.
This work extends 3,7OO feet from the
original shore. For 1000 feet beyond
extend double lines of such work set
twelve feet apart, which, being heavi.
ly ballasted below, strongly bOlted
through and through by large iron
rods and firmly planked over above
forms very strong, substantial
pier. From the outer end of this
double work to Dead Mans Island,
where the water is deepest and the surf
strongest, the work is of rOck-bOuld-
ers, varying in weight from fifty to
four hundred pounds, and piled in such
quantities as to make an immensely
heavy sea-wall. Along the leeward
side of the single line Of double pile
work, wherever the tides or eddies
threaten to undermine or wash away
the supporting butt, loads of these
heavy bOulders have also been dump
ed. TO give additional security, in
fact to completely insure the the sta
bility of the work at the points most
exposed to the action of the natural
currents, the constructor has built out
strong wing-dams to divert the Ordina-
ry ebb currents away from the timber
work and shoot them off to lend their
aid i'm constantly clearing and deepen
ing the main channel.


Three and half millions of feet Of
lumber and 1900 gross tons of stone
for rip-rap work have already been
used, and the work is going steadily on
i'm the most vigorous and economical
manner possible.


Previous to use, the timber is treated
thoroughly by the hydro-carbon va
pOr, which not only preserves the TIM
ber from ordinary decay, but i'm sutfi-
cient quantity, proves an eftectual pro-
lection against the boring Of the worms
which work to about two feet above
mean low water.


What will the breakwater do? First,
it will completely shnt off the farther
incoming and depOsiting of sand which
the northerly current flowing between
Dead Mans Island and Rattlesnake
Island has always brought in and left
in such immense quantities that no
dredging could sufficiently remove it
to keep the bottom clear Second, it
will shelteran additional harbOr secure
from the strong south and southwest
winds before which vessels have been
hitherto compelled to ''upanchor and
run to sea-"


How long will it thus protect aud Sc
cure that harbOr? Capt. Sears, who has
brought u thorough scientific educa-
ton, and large amount OF similar ex-
perience in the east, to bear upon the
problem, thinks that the constant de-
pOsit of surf-driven sand which is stea-
Oily banking up along the windward,
that Is, the southern side of the break
water, thus forming a bank or shore
rising from three to five feet above high
water, and all the while backing up to
windward, cannot fill up the broad bay
thus formed by Dead Mans Island, the
breakwater and Rattlesnake Island, in
less than ten or twelve years. When
that does happen, that is, when the
sandy shore has filled in the whole
present bay, it will naturally stretch
westward, lap by the corner of Dead
Mans Island, and begin to form
shOal along or near the present anchor
age. At that time, or by that time,
the commercial Importance of the port
will have increased sufficiently to JUS
tify the construction of an additional
or final breakwater, which, extending
sOutherly or sOuthwesterly from the
outer island already named, toward
deep water, will shoot the nOrtherly,
sand-bearing currents out to a depth
i'm when the sandy deposit, which must
steadily diminish from year to year,
will be spread over q bottom so deep
and broad that hundred times as
much sand could be washed upon and
distributed over it without shOaling it
to any injurious, If indeedto any per-
ceptible degree.


Upon the completion of the break
water some two million cubic yards of
former deposit which have been for
years accumulating for nearly two
miles long the main channel will have
to be dredged away. To effect this
Capt. Sears proposes to uss the new
suction dredge which by broad
fanged screw swiftly revolving within