The morning call., 1891-08-20

long rows of pine logs, anywhere from
seventy to ninety feet long. AS soon as tie
dredger has done its W ork, with big scoop
that takes up from two 10 three cubic yards
every time that its iron jaws are plunged
into the mud, the pIle-driyer comes into
play First of all the steam windIasS is
used to raise one end of the pile; then it is
guided into position, and when all is ready
the hammer or driver is allowed to fall. 1t
weighs over 200 pounds, and the effect of
such weight falling from height of
fifteen to twenty feet may be imagined.
The first shock commonly drives the pile
down four or five feet into the soft mud, and
successive blows do not show much deYia-
ticn from these figures. But when the pile
is halfway down the lateral grasp of the
mud and the Increasing resistance OF the
blue clay below render the progress very
slow, and toward the end the gain may bs
measured by inches. The first three blows
effect more than the last thirty, so obstinate
is the struggle between mechanics and the
sulen resistance OF the powers of nature.
1t is not uncommon to hear remarks from
those who watch the operations of the pile
driver to the effect that great deal OF I'M
necessary trouble seems to be taken. But
if the recent collapse and disappearance Of
several Wharyes on the water front be con-
sidered il will be seen that any structure
destined for a permanent usefulness must
heYe an anchorage at least twenty or thirty
feet in the clay itself, for there is constant
tendency on the part of the mud and made
ground above to slide bodily into the bay.
This is why, again, it will be necessary for
the section of the sea-wall now being filed
in at the old ferry-slips 10 have at least
three caissons sunk, so that solid concrete
stay or pillar may be fashioned in each.
The included area Of the triangular por-
ton surrounded by the boarding will take
about six months to dredge and fill in as
substantially as the rest of the se1-wail.
The length of this section is 800 feet; the
average breadth about $50 feet. The Har-
Dor Commissioners are doing their own
dredging; the pile-driving and construction
work is being done by the San Francisco
Bridge Company. The scows used find en-
trance from the sea front by way OF the old
ferry slips. The area is being dredged out
to depth of thirty-Six feet and the Uarbor
Commissioners steamer Governor Irwin al
ready makes its way into the basin. The
old ferry slips will be removed one by one
as opportunity offers and new ones subSti-
tuted.
AT the recent session of the Legislature
the entire city front on East street passed
into the hands of the Harbor Commission
ers, and the beneficial results of this measure
are now appearing in the shape of long
needed repairs. When that section of East
street, between Howard and Folsom, was
under the citY's care it was in a most dis
graceful condition and hundred wagons
abreast could have been driven into the open
and unguarded space left by the collapse of
the city portion of the planktng.
The piles had been eaten away by teredos
and pholades, the sand had been removed
by wave action, and several hundred feet of
the street had gone In search OF the historic
McGnty. The Harbor Commissioners are
putting in long rows of new piles, which