Re: Great Link!

Not telegraph carrier! Direct current (DC) with ground return.
130 to 160 volt D.C. terminal "battery" (supplied by storage cells (or a dynamo) at the telegraph main office in larger cities, and by rectifier/filter power supplies from commercial AC mains at smaller offices) was connected to each wire at each end of the line, opposite polarities facing so the total voltage "in circuit" was the total of the value of the two terminal supplies. Single wire, ground return.
After such a line is more than a few miles long, the DC resistance in the circuit earth return path approaches zero (nil, no resistance) and then the only resistance in the circuit is due to that of the series-connected instrument windings, and the line wire. Shunt resistance (leakage to earth) caused by insulation faults (broken insulators, greeen foliage touching the line, etc.
would affect the working of the line somewhat, especially in wet weather.
Ohm's Law applies fully here.
It is interesting to note the general lack of knowledge today of how ground-return telegraph wires actually operated.....of course that technology was over 140 years old when it practically ceased to exist around 30 years ago, so maybe it isn't so surprising after all.....
Read George B. Prescott's
"History, Theory & Practice of the Electric
Telegraph". (1866)
It will explain it all....old, old, fascinating
technology.....
I'm not aware of any "dynamo" ever at Chama...
The telegraph wires originally did not terminate there...they "took battery" at Alamosa W.U. (or Pueblo W.U.) and at Durango W.U. or in the case of 108 wire, originally at Silverton (prob'ly a rectifier there). After the line was cut and abandoned west of Chama, there was a
rectifier/filter 110 VDC power supply operating from commercial mains placed there to apply terminal battery on the two remaining Morse wires to Alamosa. For that short distance (100 miles or so) they could even just have been put to earth there at Chama and worked fine, but when the line got wet, it was always better to have the terminal battery evenly divided between the terminal ends of the line to avoid problems working the circuit(s) with heavy "escape" during wet weather. Especially since there were two wires on the line. Keeping battery on both wires at both ends minimized the "weather cross" problems that shunt faults (leakage to ground) caused.