The Savannah morning news., 1901-11-05

cry square inch of their surface. Each
of the four corner posts of the largest
tower must sand a strain of nearly 20
tons. Immence blocks of concrete form
a foundation for each tower and also
| serve as a sort of anchor to still fur
| ther steady it.
There is a variation in temperature
| of about so degrees at the Straits of
! Carquinez, and this will cause a varia-
| ton of fully five feet in the sag of the
great cables. These cables are made of
steel, and are each nearly an inch in
thickness. there being about a score of
wires in the twisted strand. Any per-
son who has ever felt the surprising
| pull on a kite string when the kite is
! high in the air will appreciate that the
| fastening of the cables at either end
| of the long span is a ticklish problem.
| For each cable there has ben provided
an anchorage" in the form of a mass
of concrete almost asSarge as an ordi-
mary room, and the great wire rope is
wound around a wheel a couple of feet
In diameter.
-Four cables span the Straits of Car
quinez, but only three are in use at any
one time, the fourth being always held
in reserve. This enables the cables TO
be cleaned or repaired at any time, and
it would be difficult to imagine a more
exciting task than that of the man who
water in tiny car suspended from the
cable, which he greases as he slowly
glides below it. Strangely enough. the
cables move less on a windy day than
on a perfectly quiet one. On a morn
ing when the air is still a person can
put his hand on the cables, when no
electric current is passing through. and
feel continuous jarring movement,
whereas. IL he take hold of the same
,a1 y la wrrl. l. l. ,sw--. -
will not only find it free from move
ment, but so absolutely rigid that he
cannot send a wave of motion out into
the span, no matter how hard a blow
be dealt to the great strand of wire.
The spanning of the cables in their
present position was of itself n novel
performance. After one end of a cable
had been attached at the south tower
the reel was placed on a self-propelling
steel barge, and this craft, assisted by
a powerful gasoline launch, was thus
towed across the straits, paying out
the cable as it went. A very powerful
little engine was used for pulling the
cables up to the hight required. 1t is
interesting in this connection to note
that when the sag in the cable was
such that 1t touched the surface of the
water of the straits the strain was only
5000 pounds, but when the engine, af-
81
gotten the cable into the desired posi-
tion, although less than hundred feet
of the wire rope had been drawn in,
the strain had increased to 22, 500
pounds. All four cables were strung
without single mishap.
BY reason Of the high bluffs on either
side of the straits, the cables, where
they sag the most, appear to approach
much closer to the water than they
really do, an this optical illusion has
given several mariners bad frights. On
one occasion when a great ship laden
with wheat was being towed up the
straits her master and the captain OF
the tug were so certain that they saw
destruction impending from the great
cables, which they had not discerned
until almost upon them, that the COM
mander of the tug, who was giving an
excursion to several ladies from San
Francisco, hastily sent them all down
into the cabin to save them from be-
ing killed from the spars and ships
rigging, which he expected would he
falling about them within a few mo-
ments. The ships masts were $50 feet
In hight. and the surprise Of the men
on deck may be imagined when, as
they passed underneath the span, the
masts lacked full $50 feet of touch
ing.
Prior to the erection of the engineer
ing marvel at the Carquinez Straits
the longest span on the North Ameri-
can continent for carrying electric
power over water was that OF an cleo |
tric lighting company in British Co |
lubmia. which spanned the Columbia |
river In sheer stretch OF 1900 feet |
Inasmuch as the new California won.