IMPROVEMENTS IN RAILWAY FOG SIGNAL APPARATUS
Year: 1874

page_text: PROVISIONAL SPECIFICATION left by Frederic William Thornton at
the Office of the Commissioners of Patents, with his Petition, on
the 18th December 1874.
I, FREDERIC WILLIAM THORNTON, of 6, Westminster Chambers,
Victoria Street, Westminster, in the County of Middlesex, do hereby
declare the nature of the said Invention for "IMPROVEMENTS IN RAILWAY
FOG SIGNAL APPARATUS," to be as follows:-
The object of this Invention is an improvement in automatic apparatųs
for applying detonating signals to the rails of railways as an auxiliary
to the ordinary visible signals, for the safer working of the traffic.
generally, and particularly in foggy weather.
I propose to use the apparatus either separately or in conjunction with
the ordinary visible signals, and it is so constructed that it shall be self-
replenishing, that is to say, when one of the detonators placed on the
rail by the apparatus shall have been exploded by a train passing over it
another detonator shall supply its place automatically by the visible
signal arm being lowered to "all right," and this detonator shall be
placed on the rail and removed therefrom until such time as it shall in
its turn have been exploded, when the same operation of replenishing

page_text: will be repeated. To do this I connect by means of a wire or lever at
any convenient spot on the wire or rod working the ordinary signal a
sliding carrier holding the detonator. On one side of the sliding carrier,
or at any convenient place near to it, I fix on to a platform carrying the
apparatus a box or magazine capable of holding a supply of detonators.
On the inside of one of the rails I fix an incline or inclines, so placed
In
that it shall be depressed by the wheels of a train passing over.
connection with this incline I fix an horizontal sliding bar on the outside
of the rails to be worked by means of a bell-crank lever. To this bar I
connect another lever, which shall by acting upon a slide working in the
magazine or box force forward a single detonator into the sliding carrier
when required. To the sliding carrier and worked by it I fix an arm
having a projection forming a fulcrum, and so arranged that the slide
which forces forward the detonators from the magazine, worked by means
of the depression of the incline shall only come into operation when tho
sliding carrier presents the detonator on the rail, and has thereby brought
the fulcrum into a suitable position to act upon the lever.
The working of the apparatus in conjunction with the ordinary visible
signals is as follows:-When the visible signal arm has been put up to
danger the apparatus working in conjunction will. have placed a detonator
upon the rail, and should the driver of the train disregard his visible
signal or not be able to see it on account of fog, as the case may be, he
will explode the detonator, and in doing this he must have pressed the
incline, and this in its turn, as already explained, will have pressed
forward a fresh detonator from the magazine into the sliding carrier,
which detonator will take the place of the exploded one on the sliding
carrier being withdrawn by the visible signal arm being lowered to all
right, but should the driver of the train never proceed contrary to his
visible signal the same detonating signal will be presented or withdrawn
simultaneously with the working of the ordinary visible signal.