The Grenada sentinel. [volume] (Grenada, Miss.) 1868-1955, 1909-11-12

must come to a stop,
knowing that that block is occupied
by another train.
The energy mentioned above is cleo
tricity, the current being obtained
from a battery neal each post. The
rails of each block are made as if all
OF one piece by connecting the joints
with wire. The extreme ends are then
connected and thus a circuit is formed
i'll which the current flows. When no
train is in the block, the mechanism
operated by the current pulls b arm
down and holds it there. When a
train enters the block the wheels and
axles, combined with the rails, form a
shorter circuit, the energy that held
the arm down is withdrawn and up it
swings to a horizontal position.
Each block is independent Of all
other blocks. When the last wheels
of a train leave it, the current re-
at the entrance is pulled down to the
proceed" position. But before the
hind wheels have finished doing this.
the front wheels Of the locomotive
have entered the next block and
caused the arm there to rise to the
stop"
For a single track line the auto
matte arrangement is the same, but
there is a signal at each end of the
block. To prevent two trains on q
single track line entering a block at
the same time from opposite ends, be-
fore the entrance to a single track
block is reached the train sets a stop
signal at the far end of that block.
and as it enters it sets the entrance
signal to stop just as Is done on
double track. Half a mile or
before reaching the entrance signal Of
each block the engineer comes to
what is called the distant" which
tells him how the other or "home"
signal is set.
AS the automatic signal is con
structed, it cannot show "go ahead"
unless the entire combination of rails.
wire, current, magnet, etc., is work
ing perfectly. If a wire parts, a rail
breaks, a battery
fails, a switch point \
opens the slightest, ~
the combination EE
fails and the re
!. . |. !. ]. !. !: !: ! / ! !. !: ! !: !. i. ]: /: | ! ! !: !: !: !: !: . r.
leased arm re- NE.A
sumes the hOri-
zontal position. So, Hk \
when the engineer in \
sees the stop sig m
nal, he knows that W
there may be a w
train on the block, N
an open switch. or
a broken rail or
signaling appa- kp
ratuS.
At night colored lights are display.
ed on the same posts. The lamps
will burn eight days without replen-
ishing, but are refilled every -four or
five days. When the home signal is
at stop, the engineer sees the flame
through a red glass. The caution light
on the distant is yellow. A green
lights means go ahead and is used
on both the home and distant signals.
Where two or more lines cross at
grade the general plan of semaphore
arms for day and colored light for
night is the same, but owing to the
complications all signals are con.
trolled by levers operated by men
from a central station. The crossing
and contiguous tracks are governed
by the interlocking system. When
this is in perfect order and the cross
ing u~noccupied, it displays stop to
every track approaching the crossing.
Any change must be made by the sig
mailman, and to display proceed" he
must first lock all other approaches
with the stop signal.
There are now about 1000 miles
of railway equipped with the block
system. The only line thus protected
every inch from Chicago to California
is via the Northwestern, Union and
Southern Pacific. One-third Of the
II miles of automatic signaling is
on the Hartman lines-and the North
western has more miles of double
track automatic than any other rail-
way.