Sounders & Relays



A telegraph relay is basically a switch that is controlled by an electromagnet. A telegraph signal present on the line would energize the electromagnets, causing a steel armature plate to move and toggle a lever between one or more sets of electrical contacts. They were most often used to connect between a local telegraph circuit (key and sounder) and the main telegraph line. As telegraph systems became more complex, with multiplex systems etc, the relays became more complex as well. Relays can be distinguished from sounders by the presence of at least 2 sets of terminal connections. Sounders (with some exceptions) only have one set of terminals, since they were generally not used to switch between different circuits.

The telegraph sounder was developed after it became clear that operators were able to read the incoming telegraph signal by listening to the clicking sound produced by the telegraph register. The sounder was able to greatly amplify this clicking sound with various improvements in the acoustics of the instrument.

When the sounder lever is pulled down, it strikes against a metal post called an "anvil", which creates a sound. Many of the early anvils were just simple machined metal posts, which were not the best designs from an acoustics standpoint. So, some of the early sounder designs by instrument makers such as Charles Chester and Charles Williams employed an acoustic base, where the wooden base was hollow with a hole in the top or bottom to act like a resonator, much like a guitar. This helped amplify the sound.

With other later designs, the brass base on which the anvil and other parts were mounted was itself hollow, which also helped act as a sound amplifier. There were even designs where the anvil looked like a metal drum (see the Gilliland Drum Sounder below), providing even more sound amplification. Eventually though, the sounder settled on a common design with a hollowed brass base and a 2-legged anvil. This progression can be seen as you browse through the photo gallery below.

The exact date when telegraph sounders came into use is not known, but it is believed the first sounder was invented by James Clark & Co. from Philadelphia around 1856. There is a simple sounder that appears to have been created by modifying a relay in the collection of the Smithsonian Museum. A picture of this sounder can be seen in the photo gallery on this page.

Below are some pictures of Sounders and Relays dating from the 1850's up to the early 20th Century. Click on each thumbnail to view the full size image:

Relay by William Clark, Philadelphia. Ca. 1846 (Smithsonian Museum) William Clark Relay, Philadelphia. Ca. 1848 Another View of the Early William Clark Relay Early Italian Relay by Carlo Dell'Acqua, Milano. Ca. 1848-1850
SW Chubbuck Relay, Utica NY. Ca. Early 1850's Ornate Relay by Henry J. Rodgers, NY. Ca. 1850 (Smithsonian Museum) Another View of the Rodgers Relay Early Caton Relay, Ottawa Ill. Ca. 1850's
Unusual Relay by Charles T. Chester, NY. Ca. 1850's. (Smithsonian Museum) Another View of the Chester Relay Palmer & Hall Relay, Boston. Ca. 1850's Hinds & Williams, Boston. Ca. 1850's
James Clark, Philadelphia. Ca. 1856. Possibly the First Telegraph Sounder (Smithsonian Museum) A Very Early Beam-Style Sounder by Charles Chester, NY. Ca. Late 1850's Early Relay by Charles Williams or Hinds & Williams. Boston, Mass. Ca. Late 1850s Another View of the Early Relay. Note the Ivory Coil Bobbins
Acoustic Base Sounder. Charles Chester, NY. Ca. Late 1850's Another View of the Chester Sounder Charles Chester Sounder. Ca. Late 1850's E. Holmes Burglar Alarm Relay. Ca. 1850's
Thomas Hall, Boston. Ca. 1860

Unknown Maker. Ca. 1860's

William Lundberg, San Francisco. 1863 Close-Up of the Unusual Spring Tension Receptacle
Early Phelps, American Telegraph Co. Ca. Early 1860's Phelps American Telegraph Co. Ca. Early 1860's GM Phelps, NY. Ca. 1860's Robert Henning @ Caton Instrument Shops. Ca. 1860's
Another Henning Sounder. Ca. 1860's A different version Henning Sounder. Ca. 1860's A.S. Chubbuck, Utica, NY. Ca. 1860's Caton Relay. Ca. 1860's
Acoustic Base Sounder. Charles Williams, Boston. Ca. 1860's Charles Williams, Boston. Ca. 1860's William Phelps, NY. Ca. 1860's Early Charles Williams Sounder, Boston. Ca. 1860's
Early Relay by LG Tillotson, NY. Ca. 1860's. Charles T & JN Chester, NY. Ca. 1860's Very Early Altoona Shops Sounder. Altoona, PA. Ca. 1860s Another View of the Altoona Shops Sounder
Shawk & Barton, Chicago. Ca. 1868 German Relay-Lewert. 1869 Phelps Round Base Sounder. Ca. 1870 Polar Relay by GM Phelps, Brooklyn NY. Ca. 1870
Another View of the Phelps Polar Relay Thomas Edison, NJ. Ca. 1870 Knox & Shain Sounder, Philadelphia. Ca. 1870 Knox & Shain Relay. Ca. 1870
Relay by W.H. Johnson, Louisville, Kentucky. Ca. 1870 Top View of the WH Johnson Relay LG Tillotson, NY. Ca. 1870 Western Union Sounder, Cleveland Ohio. Maker Unknown. Ca. 1870
Close-Up of the Marking on the WU Sounder Sounder by LG Tillotson, NY with an Unusual Curved Frame. Ca. 1870 A Close-up of the Curved Frame Another View of the Tillotson Sounder
Dominion Telegraph Box Relay, Canada. Ca. 1870 Davis & Watts Silver-Plated Pheasant Sounder, Baltimore. Ca. Early 1870's Another View of the Davis & Watts Pheasant Sounder RH Wilson, Ypsilanti, Michigan. Ca. Early 1870's
Buell "Little Monitor" Sounder, Cleveland. Ca. Early 1870's Electrical Construction Co. Cylindrical Box Relay, San Francisco. Ca. Early 1870's Electrical Construction Co. Sounder. Ca. Early 1870's Very Early Western Electric Sounder, Chicago. Ca. 1872
Note the Similarity to Sounders Made at Caton Instrument Shops, Whom Western Electric Was the Successor. Western Electric, Chicago. Ca. Early 1870's Miles Goodyear Sounder, Chicago. Ca. 1872 Davis & Watts, Baltimore. Ca. Early 1870's
Another View of the Davis & Watts Sounder Early Tillotson Sounder, NY. Ca. Early 1870's LG Tillotson Relay. Ca. 1870's "Uncle Sam" Sounder. William Davis, Jersey City. Ca. 1874 (Gil Schlehman K9WDY Collection)
Splitdorf Castanet Sounder Patent Model, 1874 Acoustic Base Sounder by Montreal Telegraph Co. Ca. 1870's Another View of the Montreal Telegraph Sounder Another Canadian Dominion Telegraph Sounder. Ca. 1870's
Side View of the Dominion Sounder Western Electric, NY. Ca. 1870's Western Electric "Camelback" Sounder. Ca. 1870's Knox & Shain, Philadelphia. Ca. 1870's
Railroad Telegraph Supply Co, Chicago, Ca. 1870's. Likely Made by Western Electric Watts Sounder with B&O RR Markings, Baltimore. Ca. 1870's Another View of the Watts Sounder Acoustic Base Sounder Marked "Wm. Hatteroth, SF". Likely Made by Electrical Construction & Maintenance Co.
Underside of the Hatteroth Sounder Showing the Large Hole to Provide Better Acoustics M.A. Buell Private Line Sounder, Cleveland. Ca. 1870's Close-Up of Paint Job on Buell Sounder Altoona Railroad Shops Sounder, Altoona Pa. Ca. 1870's
Altoona Railroad Shops Relay, Altoona Pa. Ca. 1870's George Bliss, Chicago. Ca. 1870's George Bliss, Chicago. Ca. 1870's Partrick-Bunnell, NY. Ca. 1870's
Small Sounder Made by SH Hoggson, New Haven, Connecticut. Ca. 1870's Another View of the Hoggson Sounder Round-base Sounder by W. Hochhausen, NY. Ca. 1870's Another View of the Hochhausen Sounder
Relay by Charles Williams, Boston. Ca. 1870's Another View of the Williams Relay Jerome Redding, Boston. Ca. 1870's Partrick & Carter Private line Sounder, Philadelphia. Ca. 1870's
Partrick & Carter. Ca. 1870's Tillotson Stand-Alone Box Relay. Does Not Have a Key. Ca. 1870's Another View of the Tillotson Box Relay Partrick & Carter. Ca. 1875
Unusual Sounder With Single Horizontal Coil. Maker Unknown. Ca. 1870's Another Sounder With Single Horizontal Coil. Likely Same Maker as Previous Sounder M.A. Buell, Cleveland. Ca. 1870's Another View of the Buell Sounder Showing the Tension Spring
M.A. Buell, Cleveland. Ca. Late 1870's M.A. Buell, Cleveland. Ca. Late 1870's Relay by California Electrical Works, San Francisco. Ca. Late 1870's Tillotson Sounder, NY. Ca. Late 1870's
J.H. Bunnell, NY. 1877 Patent Austrian Relay by JM Ekling. Ca. 1870's. Note the Ivory Insulators Early British GPO Sounder With Galvanometer  




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