Many thanks for this, OSD.
Slightly off-thread - but not too far - both of the Titanic films (since 1958) show the use of an all-round morse-light - which many of us will remember as a simple lamb on top of a four-by-four stanchion, operated by an on-off switch - and generally useless at a range of more than about three miles at most. This is surprising in a state-of-the-art vessel such as Titanic in 1912 - and I wonder what was the best equipment then available? It seems that Arthur Henry Webb Aldis, inventor of the Aldis Lamp, was born in 1878, which would make him still a young man in 1912 - and even younger at the time of the WARATAH loss.
Signalling lamps as I remember them (not all of which were Aldis lamps) were of three types, all simple in design and all of them streets ahead of the all-round lamp described above, as attributed to Titanic. From memory, the standard Aldis lamp was a strong light whose beam was deflected, as required, by a simple reflector and mechanical leverage. The light-beam went up and down, rather like the dipping of headlights on a car. A larger type had the reflector fitted rather like blinkers on a horse, with the reflector being pulled back (and opened out) as required, by mechanical means. A third and usually much larger type had shutters rather like a venetian blind, again operated mechanically. All were so simple in design that it seems probable that something very similar would have been in use long before the Waratah incident - and even more probably before the later Titanic incident. The Royal Navy would surely have had the shutter-type signalling lamp long before 1912?
Answers on a postcard, please!