IMPROVEMENTS IN RAILWAY SIGNALS
Year: 1862

page_text: PROVISIONAL SPECIFICATION left by Henry Thomson at the Office
of the Commissioners of Patents, with his Petition; on the 31st October
1862.
I, HENRY THOMSON, of Buckden, in the County of Huntingdon, Engineer,
do hereby declare the nature of the said Invention for "IMPROVEMENTS IN
RAILWAY SIGNALS," to be as follows:-
This Invention consists of certain improvements in the arrangement and
working of signals for railways, whereby they are rendered self-acting, and, by
the adoption of which personal attendance. is dispensed with, as well as the
uncertain and hazardous results thereof, and whereby a safety from collision
of trains is perfectly ensured, there being no possibility of trains.coming
accidentally in collision, either on the main line or in tunnels, or on branch
lines, or at junctions, since the driver of a train will always be able to ascertain
by the signals whether or not another train is in advance within a certain
regulated distance of his train.
I propose to place on the inside of the outer rail, both on the up and down
lines, a bar or series of bars of iron, according to the length of bar to be acted
upon, and to adjust the level of the bars so that the passage of a train or engine
shall depress them by the action of the flanges of the wheels of the engine and
carriages. I propose to connect these bars with levers, rods, brackets, and
springs, and with chains or wire ropes, so as to form a communication or con
nection with a hand signal by day, or with a lamp signal by night. Now it is

page_text: obvious, that by this means the passage of the train or engine over the bars
might be made to indicate the danger signal, and so prevent another train from
passing the same until the signal should be removed, which is effected by a
similar arrangement being adopted at a further point on the line, and a communi-
cation being made with the signal by means of a light wire rope passing over
rollers or pullies at the side of the line. Thus by a system of signals established
all along a line of railway the trains would always be kept from approaching
each other within a certain distance at which it might be considered advisable
to regulate the position of the signals.
With respect to tunnels, to which the Invention is especially applicable, I
place a danger signal at each end of the tunnel, which the engine on its
entrance causes to be displayed; but in tunnels I propose to arrange the bars
in one continuous and connected length or series throughout the tunnel for the
following reason:-If the engine were to reach the next signal after leaving
the tunnel, and so actuate the signal at the other end, so as to indicate safety
to an approaching train, and one or more carriages had become detached from
the train during its passage through the tunnel, an accident would necessarily
ensue on the arrival of the next train, but by the plan of continuous bars in
the tunnel it follows that where the carriage or carriages are left they will
press on the bars and maintain or expose the danger signal, notwithstanding
the passage of the fore part of the train and its action to reverse the signal
from danger to safety.
When approaching junctions, the trains should respectively actuate a signal
at the junction when at a distance of 300 or 400 yards, which would prevent
the possibility of two trains arriving simultaneously at the junction. These
signals being self-acting are rendered as certain and unfailing in their operation
as can be possibly desired, and they only require to be attended to for the
purpose of cleaning, oiling, or repairing the various parts.