The Telegraph Office

"Key, Double Current, Mark II" c. 1908

Foreign Key Photo Gallery

A Photographic Reference for Wire and Wireless Telegraph Key Collectors and Historians

by Neal McEwen, K5RW

k5rw@telegraph-office.com

Last Updated 22 September 2001

Copyright © 2000-2001 Neal McEwen

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The Foreign Key Photo Gallery consists of photographs of telegraph keys, and related artifacts for identification and reference purposes.  Below you will find keys and other telegraph instruments from Britain, France, Italy and other countries.

Telegraph technology and the telegraph equipment in Europe and other countries was different from American technology and American equipment.  For example, the typical American key has the lever return spring in front of the fulcrum with the spring in compression.  A typical European key has the lever return spring behind the fulcrum with the spring in compression.

American landline keys have one set of normally open contacts which 'make' and 'break' a telegraph circuit.  As you examine the keys below you will find that European landline keys have two sets of contacts.  In addition to the normally open contacts, there is a set of normally closed contacts.  This is required because Europeans used open circuit telegraph lines while Americans used closed circuit telegraph lines.

Each of the telegraph instruments listed below is shown with a thumbnail photo.  For a full size photo, click on the thumbnail photo.


  • Danish ‘double current key’ made by G. N. T., Great Northern Telegraph Co. -- The key is marked "ST. N. T. S.,” meaning Store Nordiske Telegraph Selskab which translated to English means Great Northern Telegraph Company.  The key was manufactured in Copenhagen.
    The key is a "G. N. T. Post Office pattern double current key type 200/604."  The serial number is 7999.  John Radich, VP and General Manager of G. N. T., has factory serial number records dating from 1912 when the current serial number was 42,252.  Assuming the same number of keys were made each year and working backwards, Radich guesses the key was made in 1882 or 1883.  Assuming lower production numbers, the key was likely made before 1890. 

    G. N. T. started business in 1875.  Further information on the key and G. N. T. can be found "Morsum Magnificat" Number 59, August 1998.

    Double current keys apply voltage to the line when the key is up as well as then the key is down, reversing the polarity of the voltage between 'mark' and 'space.'  The rates of charge and discharge of the telegraph line are accelerated as compared to 'neutral' or 'non-polar' systems.  Hence double current systems generate cleaner signals and permit higher transmission rates.

    The line drawing at the top of this page is shown as "Key, Double Current, Mark II," in a 1908 British Army training manual.  Double current keys are fairly common in Britain.


  • Marconi radiotelegraphy key model PS-213A, unmarked --  This British key was made by Post Office shops after WWII.  The name Marconi is not present on the key.  However, most Marconi historians believe that ‘PS’ is a Marconi part number and or drawing number.  This particular key was used on the cable ship ‘Alert.,’ of British registry.  ‘Alert’ was decommissioned in 1960.
    The serial number "No. 120873" is under the knob on the vertical surface of the bakelite base.  The knob has been smoothed off at the top left, possibly for the comfort of the operator.

    These Marconi keys were used by British coastal stations such as Portishead Radio, "GKA," and others.

    Note how the design is similar to early Swedish landline keys.  Several key makers in Europe, including Finnish, Norwegian, Danish and Swedish makers, used this design for radiotelegraph keys.  The same design was used by the British GPO shops in Ruby to make keys for Portishead Radio in the 1983 when Portishead was moving to a new building.

    Marconi may have contracted with a Scandinavian maker for this key.


  • French PTT landline key by Digney Fres. & Diverneresse -- This key is based on the French Post Office design of the early 1880s, though it could have been produced until 1910.  This design of this key is shown in the book "L 'Electricite", by Baille, 1883.
    The fulcrum pin of this particular key is threaded and screws into the lever.  "Digney Fres. & Diverneresse" is stamped into the lever in a small 3/4" oval just over the fulcrum.

    Fres. is the French abbreviation for 'brothers.'  Digney Fres., a Paris based instrument maker, was known to have made a variety of telegraph instruments including Morse registers.  Little is known about the partnership of Digney Fres. & Diverneresse.


  • Gilbert Bros. baseboard set -- This British baseboard set was built in London for the British Army during W.W.I.  It appears to have been built to order, for the key is by A.T.M. (stamped 1915), the sounder is a G.P.O. sounder and the galvanometer is marked N. T. Co. Ltd. 
    • This baseboard set is transported in its own wooden carry case.  The knob on the key is made from buffalo horn.
      This baseboard set is of the "direct sounder, intermediate station" type.  When the key is up, the baseboard set has the sounder in the circuit and hence the operator can copy all stations on the wire.  When the key is depressed to send, the sounder is out of the circuit; British telegraphists listened to the click of the key and watched the galvanometer swing left and right to monitor their own sending.

      The galvanometer was also used to permit the telegraphist to determine if he was actually applying current to the wire when transmitting.  Likewise, the galvo was used to determine the presence of an incoming signal even it the sounder was incorrectly adjusted.

      On the base of this set, carved into the wood, is "6 London Div."  This was part of the British Army's III Corps and was one of the first Allied units into France during W.W.I.


    • French PTT landline key, unmarked – On this French Post Office key, there is a figure ‘3’ in a circle in the wood base under the knob.   This key is believed to be a 1907 or 1913 design.  Note similarity to earlier French PTT designs.

    • Ducrete and Roger spark key -- This 'oil break' key was used on French military aircraft during W.W.I.  The contacts are immersed in oil which is in a small cup sunken into the base.  The oil quenches the arcing between the contacts.  The key can operate in an explosive atmosphere and is thus a 'flameproof' design.
      Notice the large protective skirt under the knob to guard the operator's fingers.  The reddish color of the skirt is due to the material being made of compressed oxblood.

      Ducrete and Roger manufactured this key in Paris, France.   The Ducretet name is associated with the early development of wireless in France; he was an early experimenter and maker of wireless apparatus. Descriptions of his experimental transmitters and receivers are shown in Electrical World and Engineer in 1899.  Ernst Roger was a collaborator in the Ducretet experiments as early as 1898.

      During World War One, the Ducretet and Roger shops were devoted entirely to the manufacture of military communications apparatus and special equipment for the Navy such as periscopes and microphones.


  • Unmarked British Radiotelegraph key -- This unmarked key is a typical British Post Office "single current key" design introduced in the late 19th century.  This particular key has been modified for radiotelegraph work by the maker.  Note the current strap between the lever and fulcrum.  There is a protective skirt under the knob as is typical of wireless keys.  Also note the steel sub base; the key appears to slide in and out of some sort of transmitting apparatus.   Even though intended for wireless use, the key still has the normally closed contact (not used),... further evidence of its landline heritage.

  • Keys of this British Post Office design were made for many years with slight variations of detail by various companies, including Elliott Bros., Walters Electrical, Siemens Bros., Great Northern Telegraph Co., A.T.M.,  Silvertown Works, and the British Post Office itself.
     The vintage is a curiosity and could be anywhere from W.W.I to the 1950s.

    • M.A.E.S. spark key -- This small spark key was used by the French Army during W.W.I.  The key was used with the E3 spark transmitter and crystal receiver.  It is rather small by spark key standards, having only 5 mm contacts and a bakelite or hard rubber base.
    The protective skirt is not original.  As made, the skirt was a pale red composite material as identical to the skirts on the Ducrete and Rogers oil break keys.
      This key was made in Trevoux, Ain, a small town near Lyon, France.  M.A.E.S. was a maker of small parts, such as condeners for wireless apparatus.  Otherwiese, little is known about the maker, M.A.E.S.

    • Houghton-Butcher Mfg. Co. Ltd., mechanical learner's key -- Notice the absence of any terminals on this British key.  No batteries are required.  This key was used by British armed services to teach Morse by key click sounds during WW I.  The key is marked
    Key, Dummy, Signallers
    Houghton-Butcher Mfg. Co. Ltd.
    1917
    No. 7502
      This particular key was used by the 3rd and 4th battalion, Royal West Sussex Regiment.

      Heliograph and lamp signallers were trained in the Continental Morse Code on 'dummy' keys.    The instructor would call out a letter and then send it on the 'dummy' key; the student learned the sound of the letter and wrote them in block capital letters. ( It is interesting to note that instructors used 'toc,' 'ack,' 'beer,' 'emma,' 'esses,' 'pip' and 'vic' instead of T, A, B, M. S, P and V when calling out letters; this was done to avoid confusion with similar sounding letters such as T and E or A and H for example.)

         A British Army training manual states, "By obtaining a complete mastery in sending on the dummy key, much time will be save in acquiring proficiency in sending, both on the heliographs and lamps."  Students were not allowed to practice on the heliograph until they had mastered the 'dummy' key.


  • Reid Bros. British Post Office Relay -- This relay is a "Post Office Standard Relay A".  Telegraph sounders require a considerable amount of current to work properly.  On long lines there is difficulty getting enough current to the sounder.  Therefore, on long lines, the sounder is replaced with a relay which requires much less current to operate.
  • The relay does not sound out readable signals, but opens and closes a local circuit in which there is a sounder and battery.  The solenoids of this relay have two windings  of 200 ohms each and can be connected in series or parallel. 

    The Reid Bros. shops were in London.  The vintage of this relay is not known, but the diagram above is from a 1908 British Army training manual.


    • Italian PTT landline key, unmarked --  Keys similar to this one were  made by Forcieri. Forcieri made two models, one with a closing lever and one without a closing lever as shown in the photo.
      An Italian writing in Morsum Magnificat No. 49, page 45, seems to think that the model without the paddle closing lever on the lever arm could be a training key for the Posts and Telegraphs Administration of Italy. 

      Christian Chefnay puts the age at about 1920.  Chiarucci Eliseo, states that these keys are quite common in Italy and some are dated on the bottom; he has seen dates as early as 1885.  Eliseo further states, "Other [key of this type] have marks with info of the PT zone they were used."


    • French 'folding' key, unmarked -- This key was used in French W.W.I wireless transmitters or buzzer sets.  Although unmarked, this key is identical to keys integrated in the Type 4 spark transmitter made by Radiguet & Massiot of Paris, France.
      The key shown has been removed from its original transmitting apparatus and reassembled on a new  wood base.  Note the similarity of the hardware to French PTT keys. 

      There seems to be quite a few different 'folding' keys made in several countries and are related to W.W.I. portable transmitting apparatus.

      Note similarity to U. S. Signal Corps. J-3 key which was used with a small portable ground induction telegraph set, the BC-16. 

      It is interesting to note the 1920 U. S. Signal Corps description of the  J-3 key: "KEY, type J-3: Telegraph; adjustable, folding; [British style, tension spring extends from lever through wood base]"


    • Steward mechanical learner's key/sounder -- Notice the absence of any terminals.  No batteries are required to teach Morse code by key click sounds.  Made in Strand, London.  Note the unusual oval shaped wooden base.  Believed to be predate W.W.I..
    Mechanical learner's set date from the mid 19th century.  American instrument maker L. G. Tillotson, in an 1870s catalog, shows a "Mechanical Telegraph Instrument" with a patent date of 1870.

    • Dyna radiotelegraph key – This French key is a model PTT 1927.  It was originally made for the French Post Office, later used by the French Army and even later sold to radio amateurs. 
    Note the protective disk under the knob and the similarity to Ducrete & Roger spark keys.  Dyna telegraph instruments were made in Paris, France.

    • Jardillier radiotelegraph key – This French key is a model PTT 1927.  It was originally made for the French Post Office, later used by the French Army and even later sold to radio amateurs. 
      Note the protective disk under the knob and the similarity to Ducrete & Roger spark keys.  Jardillier telegraph instruments were made in Issy, Les Moulineaux, France. 

      Jardillier also made a French J-38. 


    • French 'folding' key, unmarked, for lamp signalling – Removed from lamp signalling set.  The base is original; note the original mounting holes. Believed to be W.W. I. Vintage.
    This key applied voltage, supplied by a generator, to the signalling lamp.  When the key was in the up position, the generator was terminated with a resistor equal in load that of the lamp.  The generator was an external hand cranked generator similar to generators on motorcycles.

    When the key lever is in the vertical position the key is stored in the lamp signalling box.  When the key lever is in the horizontal position it protrudes through a vertical slit in the lamp signalling box.

    • Lucas key -- This small British key has two terminals, so was used for radiotelegraphy.  This key was used in W.W.I. and sold as surplus shortly thereafter.  Key is on a bakelite base; the wood sub-base is not original.
      Lucas also made a lamp signaling key, unlike this key, and for many years has made electrical parts for the British automotive industry.

    • Japanese key, unmarked, c. W.W.II -- This key of unknown make was taken from a bombed out Japanese communications post on Attu Island in April of 1943. 

    • Note how the design is almost identical to German keys of the period and earlier.  The key was kicked out of the burning radio installation by W5HFU.


    • Stuart - Moore Increment key, c. 1910 -- This British key was used in quadruplex telegraphy.  Increment keys are shown in a 1911 Siemens catalog, being described as basically a Single-current key "arranged on the plan of a Double-current key". 
    Notice that the increment key has three terminals like a "single current key." Schematically, the increment key is the same as a single current key.  However, it is mechanically arranged such that 'make' happens as soon as the lever has started it downward motion rather than at full stop like the single current key. The Increment key is also shown in a 1908 British Army telegraph training manual as depicted below.

    The increment key alone did not enable multiplex telegraphy; it was used in conjunction with other sophisticated instruments.  Quadruplex instruments allow four simultaneous transmissions on a single telegraph wire, two in each direction  Each end of the quadruplex wire had an increment key and a "reversing key.".  Quadruplex telegraphy was a mature technology by the 1880s.


    • Edison and Swan "Q and I detector,"  -- This British Q and I detector is an elementary galvanometer made for telegraph, telephone and other types of electrical maintenance workers to make rough battery checks, find faults, number wires, and other similar tests.  It is not intended to measure absolute current or to be part of a working telegraph set.

    •  

       
       


      The "Q and I" stand for "Quantity and Intensity," 19th century electrical terms, which are misleading terms to describe the coils.  The "Q" coil has a resistance of .2 ohms.  The "I" coil  has a resistance of 100 ohms.

      The "intensity" coil is used for localizing faults in lines using a series resistance.  The "quantity" coil is used primarily for battery testing.

      This meter, c. 1917, was made by Edison and Swan United Electric Light Co. Ltd, the company that formed as a result of the 1883 merger of Thomas A. Edison's company and Joseph Swan's company.  Joseph Swan of England, invented the light bulb at the same time Edison did.  They sued each other, but settled and co-founded Edison and Swan.

      This Q and I detector was found in a small leather case with British Army markings dated 1917.



    Credits:  I would like to thank the following collectors, historians and translators for helping me to identify some of the pieces shown above.  Thanks and a tip of the hat to Wyn Davies, Tony Smith, Zyg Nilski, Yann Conan, Jean Le Galudec, John Francis, Doug Palmer, Pete Malvasi, Jim Kruezer, Fons Vanden Berghen, Abbye McEwen, Billyelu Henderson Krone, Jerry Broudy and Chiarucci Eliseo.

    Bibliography:

    Brenni, Paolo. 19th Century French Scientific Instrument Makers, VIII: Eugene Ducrete (1844 - 1915), Bulletin of the Scientific Instrument Society, No. 46. 1995.

    Herbert, T. E. Telegraphy -- A Detailed Exposition of the Telegraph System of the British Post Office, Whittaker & Co., London, 1916.

    Kleinman, R., Kreuzer, J., Blisard, K., Kreuzer, F. Spark Keys: The Interplay of Wireless History and Technology Antique Wireless Association, Vol 14, 2001,

    Nutting, Larry. J-Series Telegraph Keys of the U. S. Army Signal Corps, 1993.

    Renaud, Paul. Annual Exhibition of the French Society of Physics, Electrical World and Engineer, 1899.

    Tillotson, L. G. L. G. Tillotson & Co. Price List of Telegraph Machinery and Supplies, Cables, Office and Magnet Wires. c. 1870s.

    Ward, E. W. D. Instructions in Army Telegraphy and Telephony, Vol. I - Instruments, Harrison and Sons, London, 1908.


    All photos are copyrighted.

    Non-profit organizations and individuals may link to the photos, giving proper recognition to The Telegraph Office.  Those parties with pecuniary interests must seek permission to use.

    For more information, visit the Telegraph Office home page

    Neal McEwen, k5rw@telegraph-office.com