The morning call. [volume] (San Francisco [Calif.]) 1878-1895, 1891-05-13
HARBOR DEFENSES.
Important Works Commenced on
Angel Island.
The Long-Delayed Submarine Mines Now to
Be Laid DSwn-A New Wharf and Big
Guns for Fort Point.

TO the defenSeleSS condition OF san Fran
cisco Harbor is likely to be speedily re-
moyed-at least so far as the preparations
for torpedo defense are concerned.
The torpedoeS are here already, safely
slowed away at Goat Island, and a cOmpre-
hensive plan of submarine mines is now be-
ing put into execution.
1t is safe TO say that even now the harbor
could be filed with torpedoes, connected
with the existing caSemated gallery at
Black Point, in few days time. When
the Angel Island galleries are completed,
the more complicated and more effective
system of mines with triangulatiOns can be
carried out in manner TO make the inner
haTbor absolutely secure against the inVa-
sion of hostile cruisers. Practically, the
space between the Heads and Goat Island
could then be made untenantable for an
iTon-clad fleet.
THE NEW CABLE GALLERY.
A CALL reporter found yesterday that
quite strong force of men is at work in the
Windmill Ravne on Angel Island and Will
continue TO labor till the new cable gallery
is completed. In structure the gallery is
precisely similar to that at Black Point,
and, when completed, will be absolutely
bOmb-prOOf, while exhibiting from sea-
ward no indication whatever of its presence
The location of the submarine mines with
which these casemated galleries are to be
connected by electric wires is. of course,
national secret jealousy guarded. More
than this, the wires will not be laid down
till an emergency arises. In such a case
they could all be Lard down in night and
then it would be hail, Columbia! for the
hostile vessel seeking 10 thread its way
through the channel.
THE SUBMARINE NINE.
Practically the submarine mine is of two
Orders-the mechanical and the electrical.
Both were used with effect during the civil
war and both could be brought into utility
in San Francisco Bay. In the mechanical
variety, which Is chiefly available in shall
low water, the explosion Is caused by con-
tact Of an approaching vessel, clrcum-
stance which limits its application TO
quarters where-the injury would be inflicted
on foes only Moreover, such distractions
are easily iished up and removed. As wing
deienseS, however, they have their useful
ness, and in hasty eXlempOrlZed defense of
the bay mechanical mines might play an i'm
pOrtant part.
SHARIN G THE RESPONSIBILITY.
The electrical submarine mines now under
construction have this paramount ad-
Yantage-that friendly vessels may run up
against them or pass over them without
damage, while the responsibility for the
actual explosion is shared by two persons
at different stations who can act easily and
intelligently III concert but neither Of whom
can explode the mine by individual action.
The description of the operation is COM
pick by reason of the mathematical ele-
mentS involved, but the principle itself is
literally simple as A Is G.
FOCUSED BY TWO OBSERVERS.
A hostile vessel is discerned approaching
e.. Il
by two observers, stationed, for instance, at
Angel Island and Black Point. Each of
these observers, safe IN n casemated gal
lerY, has a little table before him, with but
tons, connected with the wires leading TO
the submarine mines.
The locations and bearings Of these mines
being absolutely mapped on the chart be-
fore the operators, all they have to do is
to await the developments. The doomed
vessel crosses the intersection OF line l from
Angel Island and from Black Point. Each
OF the operators presses a little button. but
nothing occurs because the circuit is not
com letely closed, But now the vessel
crosses another intersection. This time it
Is Ne. 3, at Angel Island, and No. 3, also, a:
Black Point. The operators again press the
buttons, and-well-the mine does the rest
PRACTICAL APPLICATION.
This is the principle of the submarine
electrical mine expressed in its very sim
is complicated by the employment Of tele-
scopes. connected with an ar: furnished
with contributions at the critical points.
This does not entirely supeTSede the primi-
tive system OF exploding the mines on a
signal from lOOkOuts on the hilltopS but is
vastly superior in that il removes from a
delicate operation the factor OF individual
nervousness or enthusiasm.
UNDER ACT OF CONGRESS.
The submarine mines in San Francisco
haTbOr were provided for in General Orders
% Issued at army headquarters In Washing
ton on March ., 1889, under an act OF Con-
grpSS directing $3.50, 900 to be appropriated
for closing the channels to the principal
seapoTts, S250,0OO for casemates and cable
galleries TO operate submarine mines. $780,
coo for practical instruction in torpedo
service, $4,000 for the purchase of movable
submarine tOIped0es and So, 900 for tor
pedO-shed in San Francisco harbOr. The
same act authorized $50, 600 to be expended
for the finishing and SSembling of 6-inch, |
10-inch and 12-lnch guns made from fOrgings
procured under the act of September, 1888.
THE CITY CEMETERY.
1t is proper to note here that whatever ac-
ton may be taken in regard to the cOndem-
nation of the City Cemetery for defensive
purposes. the batteries TO be erected on that
site and on other points guarding the bay
cannot be put in position under four years.
This Will be easily seen from glance at the
terms OF delivery to the Government of the
big guns now under construction at the
Watervliet Arsenal The dates fixed are as
follows: