The record-union., 1894-09-22
IGNORED CURRENT AND DRIFT CoNDI-


IGNORED CURRENT AND DRIFT CoNDI-
TIoNs.
First-The board of 1892 ignored the
current and drift conditions along the
| shore as above fully stated, or rather,
they did not believe the sitting of the
harbor to any great extent would result
| from continuous breakwater connected
with the shore.
They differed with the board of 1891 in
this. and l think they were in error.
CONFUSING THE DIRECTION OF THE
WIND.
Second-The board of 1892 confused the
direction of the wind with that of the
swell, and calculated protected or unpro-
tected areas in the two localities accord
ing to wind directions rather than swell
directions, and TO the prejudice of both
points, particularly Santa Monica. In
this also they differed from the board of
1881, and again l think enormously.
1t requires detailed reference to under
stand this. In House Elk. Doc. No. Al, D.
Is. of the report of the board of 1892, they
compared exposures by using direction of
wind rather than SwellS, although they
copied statements from the report of the
board OF 1891, and from the statement of
Professor George Davidson, both OF which
statements are emphatic in the opposite
Il. Ds &.
lines IL to 20, and p. I04, where Professor
Davidson states: I'm our southeasters the
swell OF the Pacific comes from the south
west."O
EXPERIENCE AT THE NEW WHARF
At Port Los Angeles, since the report of
the board of 1892 was made confirms the
above statement; the very heavy swell9
come from southwesterly direction NOV
ing toward the coast about north 3Oo east
~, =
the ordinary swell is about north 5t0 east
magnetic. These directions are from
careful observations at Port Los Angeles
wharf.
In designating a break water the loca-
tlon should take into consideration both
OF these directions and be placed so that
1t would offer the largest amount of pro-
lection.
SERIOUS ERROR OF ENGINEERS.
By using wind, not swell direction.
rom the southeast to determine the pro-
tected area behind a break water at Santa
Monica the board OF 1892 erred, greatly to
the prejudice OF this harbor, making the
area ~ acres, while from the careful sur
Vey OF Port Los. Angeles, made in 1898,
and baSlng the calculations on the length
OF the breakwater designed for Santa
Monica by the board of 1891, and placing
II IN tathoms l find protected area of
100 acres between the 4l-tathOm curve
and the breakwater.
ECONOMY OF LOCATION.
Third-While it may possibly be a mat
ter OF no great importance, as suggested
by the board of 1892, to build in the most
economical location, yet, as the largest
estimate given by the board of 1892 for
Santa Monica might be used to the preiu-
dice OF that location and has been so
used, 1t is necessary to refer to estimates
Ihe board OF 1891 made difference in
favor OF san Pedro OF about 500. 600
u, ,S43, 40 at Santa Monica and 81 I2j lO6 at
San PedrO-Which seenee to be a matter
OF importance TO the Chief of Engineers
lsee EX. Doc. No. 80, p. =. Mr.. Hood, i'll
ms statement before the board of 1892
(see Elk. Doc. No. Al, p. l0S), showed that
tnls difference was due to the fact that
the former board had not discovered the
pest ana most economical position for
breakwater in Santa Monica Bay, and
that had they done so there was no doubt
OF the estimates having been in favor OF
Port Los Angeles. The board of 1892 ad-
mlts the fact OF the lesser volume o.
work at Port Los Angeles, but the esti-
mate turns out to be in favor of San
Pedro, caused by changing the position
OF the breakWdter at san Pedro. bringing
considerable portion of it into lesser
depths than proposed by the former
board, and the adoption, unwisely, |
about 70 per cent of that OF the former
board. Even assuming this new section
and new location to be correct, the esti-
mate ought not to be used in comparing
1t with the cost of one at Santa Monica
which was IN deeper water and had a
much larger section.
ERROR IN BREAKwATER CONSTRUCTION.
Fourth-The board of 1892 have made
their Dreakwater the weakest where it
I Onpht to ne the 1I io
the extreme IoW-water line on the sea-
SIDE. From that point 10 extreme high
water, about eight feet, and above that TO
the top of the work, about ten feet
eighteen feet in all--they have designed
slope practically l on Isl. A slope of
rubblestone breakwater OF this steepness
could not possibly stand, even while
building the breakwater. The return
waves of the swells would continually
drag the stones down until they had
formed 4 stable slope of not less than
on l, probably q on l, as designed by the
board OF 1881. II this slope which the 1891
board applied to Santa Monica had been
applied by the 1892 board to San Pedro it
would have considerably exceeded in
volume the Port Los Angeles breakwater
and consequently cost more.
A RECOMMENDATION.
/ may be pardoned for recommending
on this or similar work of the Govern
ment a rounded crown of large rough
stone, from One-half to three cubic wards
in dimension, laid with as smooth a sur
face as possible, with chinkS of smaller
stone and spawls we'll rammed in. This
kind of work should extend from ex-
treme low water on the seaside, up over
the crown, down to extreme low water
on the harbor side. The waves will run
up the slope and cover the crown with
little damage to a well-laid surface of this
kind.
THE ENGINEERS EXPERIENCE.
In designating the top work for the
Tampico jetties, when sand for good con-
crete. which had been planned, was not
available, l fist examined Jwentv-tWo
harbors in Europe to learn the results of
various kinds of work. The works at the
mouth of the Mas, in Holland, have 10
concrete Whatever, and yet have tor fifty
years wlthstood successfully the heavy
swells OF the North Sea with very small
annual expense. They are built as I have
recommended above.
At Tampico, SO far as thoroughly ap-
piled, this plan has worked satisfactorily.
l fully concur with the boards to use
rubble entirely. | believe this material.
II properly disposed on suitable slopes.
will stand in this part of the Pacific
Ocean, and the break water require but
small annual outlay for maintenance
Ten thousand dollars should cover the
annual outlay, which is more than
twenty-four break kwaters in Italy. on the
Mediterranean, cost on the average per
annum; the cost OF running foot of break
water there is less than 81.
USE OF THE INNER FACE OF THE BREAK
WATER.
Fifth-It will not be practicable to use
the inner face of the break water for tracks
and wharves, as proposed by the board of
1892. The waves Will very often break