The morning call., 1895-02-14

Mr.. Holmes had in his reply fortified his
(Allardts s) position. Holmes had said the
seawalI had not moved out an inch since
it was built years ago, and as Allardt ad-
vocated for the ferry the seawall plan of
dumping broken stone in the mud until it
became fixed foundation he considered
that this had demonstrated the correctness
of his plan.
"It is simply the reversal of the present
plan" he said, land is the plan of the
Oakland mole and of all similar works
throughout the woodwork that has stood
the test. They have put rigid structure
on flexible foundation, while. as l say,
the reverse of that proposition is good en-
gineerlng. To say that the mud in the
bay at Market street is $50 feet deep is
mere guesswork. The water between the
shore and Goat Island is only ninety 1eet
at its deepest, and it is not likely that the
mud is so deep. 1t is patent to any one
that broad fiat surface will not sink in
the mud as will pile, and therefore would
have made surer foundation.
Mr.. Holmes says the old seawall has
not moved outward an inch, but he said
nothing about the new wall-that built as
a part of the ferry foundation and finished
8 couple of years ago. When that was put
in it was straight. l live in Oakland, and
have occasion to see the wall daily, and l
am not so certain that it is straight now.
At any. rate, | think it would be proper to
take the precaution to run line over it to
see that it is all right. | am not disposed
to be an alarmist, but this is matter in
which the public at large is interested, and
it should be Investigated on cool, dispas-
sionate scientific basis.
Gas to the old seawan being protection
to the ferry structure from the weight of
the newly made ground behind it, | have
only to say that 1t is a well-known fact in
physics that the weight upon a retaining
wall is not in proportion to the surface
area, but, instead, in proportion to the
height. Therefore the fact that there may
be only q few feet between the new wall.
which is the ferry foundation, and the old
wall does not affect the matter in the least;
the height of the soft clay being retained
by it (Which acts as would water in this
regard) is the same. One foot 100 feet
high would require the same strength of
wall to retain it as would an area of 100 or
1000feet the same height
$50 much for that" continued Mr.. AL
lardt. Now as to the concrete. / do not
know what quality or quantity of con-
crete Is being used but ii is very i'm
pOrtant that it should be of the best, OF
course. If it is being mixed, as / am in
formed that 1t is, then l am certain there
Is room for improvement there. They are
mixing this cement dry, as l understand
1t, which Is contrary to all formulas The
best piece of concrete werk on this coast, if
not IN this country, is the dam at the
Spring Valley Water Works reservoir. 1t
is 160 feet high, and ii has been proven bv
freshets which overflow its top with four
and five feet Of water. Every handful of
concrete was thoroughly mixed with its
regular proportions of water, Just the same
as that of rock, sand and cement. The
proportion OF each, including so many
barrels of water, were thrown into square
cOrnered box which swung upon an axis
running through its center loDgitudinaIly
and which was rapidly reYolved until all
were thoroughly mixed, which means.
also, thoroughly wet, before they were
dumped into the works, where they were
then thoroughly tamped.
''The plan down at the water front is to
dump the rock, sand and cement upon a
platform, let them fall through a chute to-
gether, which is supposed to give them
sufficient mixing and thence this dry mix
ture is wheeled TO the caisson and thrown
in. 4 stream of water from hose flows
into the chute with it as it falls. A man
with a shovel down in the caisson distri-
butes it and two others tamp it down.
do not think that this is anything like
thorough enough for this work. There is
not enough water, nor enough mixing, nor
enough tamping."
To these criticisms Engineer Holmes re-
DllGu. NE IeSL OI ILLS NHOle business. as
to the concrete | mean, is weight-will it
support the weight? On some of these
solid arches we have already driven wagons
loaded with cement weighing seven tons
1t is reasonable to suppose that each of the
wheels sustain one and half tons isn't
it? Well, they have driven over the center
of the arches. That is more than four
times the weight which they will ever be
called upon to sustain-the arches | mean.
But shall submit them to a very severe
and what ought to be completely salts
factory test in few days. l shall run over
them the ten-ton roller employed in work
ing down the bitumen pavement. That
will represent fifty times the weight which
can ever get upon it in the form of the
Oakland passenger.
Now as to this lateral thrust" said Mr.
Holmes, dragging out cross-section dia-
gram of the old and new seawall, sit is all
nonsense, and I'll show you why in just
one minute. Here is the old seawall close
alongshore. It stands just where it was
built so long ago that Mr.. Allardt seems to
have forgotten about it. 1t has not moved
seaward an inch. The new concrete sea-
wall has been built further out, and will
form the foundation for the front part of
the new ferry building. That fact is a rea-
sonabe guarantee that the made land will |
not slide out upon us, as Mr.. Allardt feared |
IN bis original interview. But between |
that old wall and the new wall is this |
stretch of soft mud, with wide wooden |
platform supported on piles, and upon !