Annunciators
An "annunciator" is an automatic signalling device used to alert dispatchers to the passing of trains at certain points on the railroad.
A great description of annunciators comes from former D&RGW Communications Engineer L.E. Trump:
"Annunciators were usually homebrew devices of varying descriptions, that allowed the dispatcher to determine when a train passed a certain point without human intervention. These devices were ingeniously devised by the local linemen or signal maintainers, with help from the telephone and/or telegraph engineers, and usually consisted of some sort of track switch or track occupancy sensing device, and some sort of transmitter, either a code wheel on a Morse wire, or an open telephone transmitter located on a pole adjacent to the track that could "hear" the passing train, and put the signal on the dispatchers wire. Thus the dispatcher could determine the exact time that a train passed a certain known point.The transmitting device had a unique sound or signal so that which was which was easily determined. Example: the annunciator at Whitewater station might come on the dispatcher's phone with a "didadidadidadida" tone for a short while as the train passed. Or, the annunciator at Summit station might come on the dispatcher's wire and send a string of Morse "S" characters, etc. Sometimes, the open telephone transmitter type would be located so as to "hear" a crossing signal from the train engine's whistle etc. These were handy devices, and never fell asleep, like a live "OS" operator out in the sticks might."
Another note from John Pritchard indicates the location of at least two of the annunciators on the narrow gauge:
I'm contacting you back channel, as my memory is not entirely clear on this. But back in 1970 I came across an insulated rail joint a new hundred yards west of the trestle at Cumbres. That naturally peaked my curiosity, and I was told that this was connected to the telegraph system so that when atrain left Cumbres westbound, the Chama yard was alerted in time to call out the yard crew and/or train crews. I was also told that there was another one on the east end at Lava Tank (?) for the similar purpose of alerting the Antonito/Alamosa troops. I remember it was Ben Greathouse who told me this. Can you verify this? It would be interested to see if the one on Cumbres is still there.
Hopefully a photo and/or additional information on D&RGW annunciator circuits will surface.