IMPROVED TIME SIGNALLING APPARATUS FOR RAILWAYS
Year: 1872

page_text: PROVISIONAL SPECIFICATION left by Alexander Melville Clark at the
Office of the Commissioners of Patents, with his Petition, on the
17th February 1872.-A communication from abroad by Lawrence
White Coe, of Auburn, County of Cayuga, State of New York,
United States of America.
I, ALEXANDER MELVILLE CLARK, of 53, Chancery Lane, in the County
of Middlesex, Patent Agent, do hereby declare the nature of the said
Invention for "IMPROVED TIME SIGNALLING APPARATUS FOR RAILWAYS," to be
as follows:
This Invention consists of a clock gear and dial with a hand or pointer
to be set at intervals along a railway in such manner as to be suitably
conspicuous, and apparatus to be set in motion by the wheels of the
passing train for the pointer to automatically return to zero mark while
the train is passing, and to be set in motion to mark the passing time,
and record for the information of the next train the number of minutes
that have elapsed since the passage of the preceding onc. The said

page_text: signalling apparatus being intended for use on railroads running trains
in quick succession to indicate to the driver of each train how many
minutes the train ahead as in advance of him, which it does with great
exactness.
The clock dial, clock gear, and pointer, are all mounted on a post or
any other suitable support at a convenient distance from the track, say
on the right hand side, the said dial being in a vertical plane at right
angles to the line of the road, and the pointer being on a horizontal
pivot and being weighted on its short arm, so that when not restrained
the long arm will instantly rise to the zero mark which is at the top of
the dial or thereabout, the said pointer being free to move in that
direction independently of the clock mechanism to which it is connected
by a pawl and ratchet which lets go when the pointer goes back and
takes hold at the beginning of the movement in the other direction.
A vertical rod pivoted on the end of the long arm of a horizontal lever
placed at right angles to the track runs up to the side of the dial and has
a friction roller pivoted to the side of the upper end next to the dial and
above the long arm of the pointer so as to suspend the said rod and lever
on it for working the clock gear by the weight of the said rod and the
long arm of the lever. The short arm of said lever, which is pivoted
to any support arranged on the ground between the vertical rod and
the rail, extends to the side of the rail as close as it can and not be
obstructed in working up and down. Over this end is a long bar resting
on it at its centre or thereabouts, arranged parallel with the rail close to
the outside, pivoted to it or any suitable support at one end; at the other
end working in a suitable guide and bowing upward from each end
higher than the rail, so that the wheels of the passing train will pass over
it and press down the lever and lift the vertical rod and hold it a
sufficient length of time to allow the pointer to rise to the zero mark, and
there engage with the clock gear by its pawl and ratchet for working
said gear by the weight of said lever and rod to control the ascent of the
pointer for a given time after the train passes (say twenty minutes more
or less), so that a following train coming up within that time will be
exactly informed as to the time elapsed since its passage.
I propose also to combine with this local signal a telegraphic signal for
long distances by a telegraphic instrument in connection with the

page_text: current may be closed or broken as preferred at the same time the
apparatus is actuated for setting the clock mechanism in action.
This clock mechanism may be adjusted to run any desired length of
time before running down, as preferred.