We are restoring an old B&M two flag, lower quadrant semaphore. The hardware is all installed, the gear mechanism is functioning, we can lower both flags and spectacles electrically. Now comes the final touches. For you old timers, go back to days of oil lamps. There was a small blue lens installed on the backside of the spectacle mechanism. Looking from the backside of the semaphore, would the blue lens show light when the spectacle was in the stop position, or proceed position?
The lamp should be illuminated at all times since it's oil lit. If it was converted to electric, then it may have been connected to a daylight switch to allow the signaller to switch them off during daylight hours preserving battery life. Re-reading your post, you are probably referring to the back spectacle blanking plate (can't recall the correct term) and that blanked out the back spectacle when clear/proceed. When the signal was a stop, which was most of the time, the signaller/maintainer could see the lamp was alight at night without needing to ascend the ladder. The blue lens, BTW, may well be lunar white when lit. Possibly it has twin lens, blue inside, clear outside. Hope this helps. ps- I'm not an old timer, BTW.... well, relatively.
Thanks Gary, I do believe that you are correct in saying, that the blue lens would be illuminated when the signal was in the stop position. Then signalmen and a locomotive approaching from the rear direction would be able to determine if the lamp was lit. I am not really refering to you as an old timer, but I (myself) seem to be fast approaching that kind of landmark. Working on this old equipment gives a new perspective in the efforts and the technology of the former "good ol days". The men working back then, had to put in a full days work of difficult manual labor. I have found that signalmen did not have an easy time of it at all. Having to go out in all kinds of weather and all times of night to keeps the signals working. A new found respect for their trade. Thanks for the help. Dave
You got that right Dave. We always had trouble in bad weather, rain, snow etc. The lunar back lights also allowed an engineer to see that the opposing signal was at stop. On the B&M, back in my Dad's time, the lamps were lighted by gas. He has told me that the RR made their own gas and every so ofen would run a gas train to refill the tanks at the signal. Later on they were converted to either oil or electric.
