Posted by Jon on April 13, 2001 at 20:19:06 from 199.158.80.11:
In Reply to: Re: Electricity at Holly Howe? posted by Pete G on April 13, 2001 at 19:47:05:
Yes, a lantern or lamp can be moved quickly, but a torch can be flashed still more quickly. Also, the lamp would need to be directionally shielded so the overall light level in the room (reflections from walls, ceiling) didn't mask the lamp proper. You could do this with a bulls-eye lantern with shutter (see Dr. Watson's estimable memoir for examples of this in use). The "observatory" had rough, native stone walls which wouldn't reflect light well. A room in a house would reasonably be plastered, and painted or papered in a light colour, so giving the maximal effect of the chosen source of illumination within the room. An omnidirectional light in this situation would be hopeless for signalling, as the receiver would be forced to evaluate changes in intensity of the light, not discrete on/off flashes.
How about another theory - the light source was in the hall outside the room, and the flashes were made by opening and closing the door!