Telegraph Instruments


Defining what the various telegraph instruments used during the Civil War were is fairly straight forward.  Getting Civil War era instruments to use in our activities is another matter.  Because I wanted to confirm what I thought to be the case related to instrument types used during the war and come up with some reasonable alternatives for our demonstrations, I decided to do several things.  First, I listened to the wisdom here on this forum, and received lots of clues as to how things were.  Next I searched the Morse Telegraph club archives, of which I am a member, and then started poking around some books and texts on the subject.  I would like to share my findings and conclusions with you.  Clearly, if my references led me to the wrong conclusions, let me know. 


First I’ll discuss the telegraph circuits.  According to “The Telegraph Manual…” by Tal. P Shaffner published in 1859, the typical circuit was a set of mainline instruments connected in series with a set of batteries, or cells.  They had a ground system at the terminal stations. That means they most likely did not use a “metallic” telegraph except for perhaps private lines and/or very short runs.  According to both Pope and Shaffner, the potential of the line was 60 volts or more.  The main line instruments included a key and a relay at each station.  The relay was typically 150 Ohms.  Prescott noted in his book “History, Theory, and Practice of the Electric Telegraph” written in 1866 that they used a resistor, in fact a rheostat to limit the current on the line depending on the number of instruments “cut-in” the line.  The line appeared to run at a nominal 50 ma when all the keys were closed.  The relay controlled a local loop at each station. The local loop had a receiving instrument like a sounder connected to a local battery of one or two cups.  A register could have been hooked up in the same manner.  If a printer was available, it too was connected in a local loop.  Because of the number of cells involved, the local loop typically had a potential of between one volt and three volts depending on the battery type and condition.  Given that the local devices were four to twenty ohms in value, the local loop current was high.  Therefore a minimum complete station consisted of a key, a relay of 150 ohms, and a low resistance sounder, register, or printer.  Large offices had multiple lines and used switches to direct the line to appropriate tables.  The receiving instrument of choice by 1859 was the sounder.  Some of this can be seen in a picture of a UMTS Civil War telegraph field station where the relay is just visible.  Pictures, or I should say plates, in the Shaffner book show what the instruments looked like in 1959, and Prescott describes them in his book as well.  Pope has some great illustrations, but his book was published well after the war.  In the Pope book, you can clearly see how things progressed during the 1870’s.  Also in Pope, the use of the mainline sounder was evident, something absent from the Prescott and Shaffner book.  Also absent from the Shaffner and Prescott books are the use of KOB’s in the main line.  Reference is given in some MTC (Morse Telegraph Club) literature, and on the bottom of the two KOB’s that I own that they were almost exclusively used for training or “private lines.”  Finally, the plates and office descriptions in the Shaffner book or descriptions in Prescott do not show or mention the use of resonators.  They seemed to come into play after the war.  All this discussion means that we have a fairly complete picture of  the 1860’s station, both field and office looked like.  The question is how do we show the telegraph today given that the actual instruments used during the war are rare?  I am going to venture out to what I think can be reasonably done given the availability of equipment now.  I am speaking from my experience here in the West.  You may be able to do better if you live in the East, or near a place where you can engage with some collectors.


The key is the first item I’ll discuss.  During the war, the G.M. Phelps Camelback leg key was “the” key of choice.  I have only seen pictures.  Even if I had a real G.M. Phelps key, I don’t know that I would use it in a telegraph set up, rather I would put it on display.  Same is true for other instruments and artifacts actually from the war.  There are plans available on the web to make a reproduction Phelps key, but my craft skills are simply not good enough to tackle that.  To my knowledge, there are no companies or groups making replica signal equipment as there are for the infantry or artillery.  I guess our market is just too small.  My substitute is a Bunnell leg key, made in the 1880’s.  There seem to be lots of those around.  I have also used a Triumph legless key.  Although I really like to use a J38, I would avoid using one in a telegraph demonstration.  I think as long as we explain the differences; use of the later keys is an acceptable compromise.


Relays as can be seen in the Pope book and those typically for sale on EBay are really different from those used in the 1860’s.  I have elected to use with a 150 Ohm Bunnell that has a square fixture over the contact points rather than a rounded one.  I have also opted to use only those instruments with thumb screw wire terminals.  That is somewhat close, but again, the differences need to be explained.


The sounders used in the 1860’s are quite a bit different than what is typically seen today.  I have only seen the plates in Shaffner.  I have not seen a modern picture or found one in a collection.  The local sounder I have elected to use is a four Ohm 1875 Tillotson.  Even they are hard to find.  An alternative is something like a MESCO or Menominee, MI four Ohm local sounder.  They are plentiful, although the spring return mechanism is in the wrong place for an 1860’s version.  Again, I use those that have thumb screw terminals. 


In all cases, I think preference should be given to instruments made in the 19th century.  If reproduction Civil War telegraph instruments are available, by all means we should use them.  If we insist in using instruments with the same electrical and close physical characteristics, I think it will put us into at least the authenticity ballpark.


Placing the instruments on a table is another issue.  That seems to be what everyone did, but care needs to be take to build the table to period construction techniques.  That means for example, no plywood or Phillips screws.  Connecting wire for the instruments appears to be solid copper, something like AWG 16 or perhaps AWG 18.  I base that on having seen some original wire on a table…too bad the instruments were gone.  The insulation was very stiff.  Perhaps the insulation was Gutta-Percha.  The AWG 16 or 18 with really old style insulation is available from companies selling antique electronic supplies.


Well, that’s my shot at using instruments in our demonstrations.  It would be great if someone could build a bunch of replica instruments, but I won’t hold out for that.  If my research proves to be incorrect, or my conclusions and departure from historical accuracy seem too far off, please let me know.