The morning call., 1891-04-13

to he three signal posts marking three block
divisions. train enters the block between
A and b and by cutting the electric current
at A both blades of this pest will go to
danger and remain in that position until the
train passes B, when both blades at B will
go to danger and the top blade at A to
safety. When the train passes c the lower
blade at A will 90 to safety, as will the top
blade at B, thus indicating to another train
approaching A that the blocks between A,
b and G are unoccupled, but that train is
on the block beyond G or between c and d.
The manner in which a train is thus forced
to throw signals for its own protection is
truly wonderful. Directly under each sig
nal pneumatic cylinder is mounted whirh
is connected by means of a balance lever
and connecting rod to the signal arm. This
Cylinder is provided with single-action piS-
ton which presses the cylinder upward to
its highest position, when the signal is set at
danger-thls being the normal position Of
the whole apparatus. At the top of the cyl
inder valve is arranged which can be
orened electrically and which closes auto
matically with a spring To this valve a
pipe is connected which communicates with
supply of compressed air. Above the
valve is an electric magnet, the armature of
which is connected TO the valve-stem. If a
current of electricity is sent through the
magnet the valve will be opened, compressed
air will be admitted above the piston, which
will be depressed, and as it goes down will
force the semaph0re into the safety position.
The object attained, therefore, is that
when train is on '.5lock" in advance of
q set of signals it must automatically cut
the current of electricity from both so that
they will be thrown to danger When the
train passes to the next block, the current
must again be permitted to pass through
the upper signal magnet, forcing 1t to
safety position, but no current can be ad-
mitted to the lower signal magnet until the
second block has been passed.
The rails of one "block" are insulated
from the rails of the proceeding and follow
ing blocks. At one end the right and left
hand rails are connected by wire, contain
ing in its circuit two cells of gravity battery.
AT the other end the same rails are con-
nected through relay. The battery
"block" first touched by the train.
AS long as no train is on The
block current will pass continually
through the relay, but the moment train
touches the track the wheels and axles will
short-circuit the battery, the relay will be
thrown out of action, the circuit of the local
battery broken and the signal thus forced to
the position of danger.
Speed and safety are so closely allied to
the successful operation of railroads that
whatever tends to this end is certain of uni
versal appreciation and substantial reward.
1t Is less than thirty years since the plan by
which trains were notified of the condition
of the track ahead was adopted. From a
crude device, operated by hand, it has de-
yeloped with the aid Of mechanical con-
struction and electric power into an efficient
and beautiful system, which enhances
speed and insures safety. Its DEVELOPMENT
has been wonderful, aud each Improvement
opens up new possibilities for still. further
extension.