QUOTE (John Webb @ 1 Jul 2007, 21:55)
<{POST_SNAPBACK}>This is a response to a request from one of our newer members.
First use of colour light signals: London Underground about 1898
John Webb
This is going to be a very inadequate post - but it is about a find I had while researching... I have never seen any reference to it anywhere else or since - I do have a photocopy from the original journal but don't have a clue where in the chaos after two moves in less than two years (admittedly some years ago).
Anyway... The find was...
The LSWR carried out an experiment with a white light signal that,
as I recall, was a light effectively inside a vertical half cylinder that was mirrored on the inside. This was surrounded by a full cylinder that could be rotated in the same way that a conventional semaphore arm is rotated - except that the rotation was about a vertical axis instead of the conventional horizontal. Rotation changed the display from a horizontal white bar to a 45 degree white bar - that is the "aspects" mimicked a semaphore arm. I think that a 3rd position was suggested as possible but not used in the experiment. One signal was set up
I think between Nine Elms and Vauxhall for a trial period in
I think the 1890s. It didn't last long! It was, however, an early attempt at light signalling without arms .
I have never seen any other reference to it... I'm afraid that all I can tell you at present is that it was in the immense pile of stuff I worked my way through at The I Mech E.
A patent or proposed patent about the same time involved fitting the centre line of a semaphore arm with a line of lights.
In some ways it is rather surprising that British signalling took such a single/uniform colour light route and that (apart from MGR train unloading signals) we never went for Baltimore & Ohio (or similar) white light or colour light signals.
Sorry I can't give you a scan of the photocopy... I will try to find it - over the next decade or two,
Maybe someone else knows about the LSWR experiment?