The Plymouth tribune. (Plymouth, Ind.) 1901-1911, 1909-11-18

k~~0 clfic.
- Take three blocks at the beginning
of line with a train in each Train
IN first must not move TO second until
the train i'm second goes to third, and
tram In second must not so into third
until third moves TO fourth
AS number three goes into fourth. IT
tells train in two it has done SO. and
tialn In two going into block three makes
ine movable arm say to train in one.
Come on. I've gone into block two
AS an Illustration. let's take three
connecting rooms at YOUR home. COM
munIcating without doors. Now attach
on the right hand-goinG from the front
TO the back-of each door frame a NOV
able stick which can be pushed to right
angles with the door frame. or pointed
down about as you would point your arm
at a spot on the floor two feet from you.
Got that? Your stick represents the
semaphore. arm. Now then, the
middle room is your private office. Your
servant knows by the arm being at right
angles she must not enter. and Wi an
you are not in there the stick will point
DOWNWARD at 60 degrees and she may
usher a visitor in.
All very simple you say; but on a
busy morning YOU rush i'm your office
and Forget to change the arm to denote
occupied. The servant ushers in the last
person in the world you want there just
then-and the scheme is a disastrous
failure. Then you improve so the stic,
left to itself will remain firmly at right
angles. Can't forget that. you figure
Next thing you do is to forget to change
the position of the stick. The employee
sees signal Occupied and turns away an
important client with disaster almost
equal TO that caused by admitting the
one she shouldn't.
You change things so the stick will
move from right angle to pointing tC
the floor. when you not in your
Office. You can in walking from the
front room into your office release the
Wi 90 To hnr toll. will
stay in that position as long as you are
in there: and when you walk out OF
your office into the back room il will be-
pulled down to indicate you have vacat-
ed: and your employe may take the next
CALLER in.
I'm other words. you have changed this
device from possible human forgetful-
ness 10 a positive mechanical performs
ance YOU have an automatic signal.
Substitute the consecutive lengths oi
a railway for your rooms. and you have
the block signal
Then. as | understand It, n soma
phore arm located at the entrance 10 g
block set at right angle to the post is g
signal to an approaching train to stop.
and when pointing diagonally toward tn,
ground means keep on going?" Yes
You call il automatic?"
1t Is. Just as your stick is kept al
90 degrees incline. when your Office Is
vacant. so is the semaphore arm on tn,
line when a block is unoccupied. Wher
train enters a block il affects the en-
ergy which is part of automatic sig.
mailing. so that the arm goes to and re
mains horizontal as long as the block is
occupied"
'You build these signals so their nor.
NAL position is stop and then you apply
| force that makes them show keeI
| going. Why is that?"
Because the trains must keep going
| They have not only the problems OF
| safety, but Of hurry up. They work 10y
| minutes. and seconds. The first duty
| IS safety Having that cinched, the au.
moving. Only when something Occur:
| does this scheme cause signal to go I,
| stop position"
whats the energy You referred to?'
Electric current Where does it com,
| fromg' Battery near each post. How
| is il worked?" "The rails of each blocl
| are made just as If all one piece. by
| connecting all joints with wire. The,
| connecting the extreme ends forms
| complete circuit. The current flows II
| this circuit. Machinery made out of ex
| perience. wheels, springs and things i
| moved by this current: and its move
| ments either hold the arm down or per
| nit ii TO stay horizontal.
with no train in block. the curren
| makes the mechanism pull the arm down
/ and hold IL there When a train cnter
| a block IL destroys this combination. TIL
| wheels and arxles combined with the rail
i make a shorter circuit Electric curren
| deserts the longer for the shorter wa,
| round. The energy that held the arm
down Is withdrawn, and up II swings q
i horizontal
| Each block is Independent Of all othe
| blocks. When the last wheels of Il train
! leave H. the current resumes its flow
| and the signal arm away back at tn
| entrance is pulled down TO proceed. BE
/ fore the hind wheels have ceased doin;
| what I've just stated. the front wheel
| of the locomotive have entered the mex
| block and repeated what il did in tn
| previous blocks"