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.
After 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 relay. 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:
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| Relay by William Clark, Philadelphia. Ca. 1846 (Smithsonian Museum) |
Very Early Relay, Believed to be made by SW Chubbuck. Ca. 1848 (Museum of Communication, Berlin) |
William Clark Relay, Philadelphia. Ca. 1848 |
Another View of the Early William Clark Relay |
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| Early Italian Relay by Carlo Dell'Acqua, Milano. Ca. 1848-1850 |
SW Chubbuck Relay With Multiple Relay Contacts, Utica N.Y. Ca. Early 1850's |
Another View of the SW Chubbuck Relay Showing the Additional Contacts |
Close-Up of the SW Chubbuck Name. Serial Number 45 |
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| Another SW Chubbuck Relay, Utica NY. Ca. Early 1850's |
Close-Up of the SW Chubbuck Name. Serial Number 46 |
Ornate Relay by Henry J. Rodgers, NY. Ca. 1850 (Smithsonian Museum) |
Another View of the Rodgers Relay (Smithsonian Museum) |
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| Top View of the Rodgers Relay (Smithsonian Museum) |
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 |
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| 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 |
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| The Bright's Bell Telegraph. Invented in 1855 by Charles Bright, England. This Was the Earliest Acoustic Telegraph Used in Britain. It Consisted of a Relay, Galvanometer, and 2 "Double Plate" Sounders |
Close-Up of One of the Double Plate Sounders on the Bright's Bell Telegraph |
Close-Up of the Bright's Bell Relay |
Early Relay on Marble Base by Charles Chester, NY. Ca. Late 1850's. (Smithsonian Museum) |
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| Top View of the Marble Based Chester Relay |
Very Early Relay by Charles Chester, NY. Ca. Late 1850's (Museum Victoria, Australia) |
Top View of the Early Chester Relay |
Early Relay by Charles Williams or Hinds & Williams. Boston, Mass. Ca. Late 1850s |
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| 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 |
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| E. Holmes Burglar Alarm Relay. Ca. 1850's |
Thomas Hall, Boston. Ca. 1860 |
Unknown Maker. Ca. 1860's |
Early Relay by Charles T. & JN Chester, NY. Early 1860's |
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| Early Relay by Charles Williams, Boston. Early 1860's |
Top View of the Early Williams Relay |
Remnants of an Early Sounder by EM Pierson, Cleveland, Ohio. Early 1860's |
William Lundberg, San Francisco. 1863 |
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| 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 |
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| Robert Henning @ Caton Instrument Shops. Ca. 1860's |
Another View of the Henning Sounder |
Another Henning Sounder. Ca. 1860's |
A different version Henning Sounder. Ca. 1860's |
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| Relay by Robert Henning @ the Caton Instrument Shops, Ottawa, Illinois. Ca. 1860's |
Top View of the Henning Relay |
Early Sounder by Charles T. & JN Chester, NY. Early 1860's |
Another View of the Chester Sounder |
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| 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 |
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| William Phelps, NY. Ca. 1860's |
Early Charles Williams Sounder, Boston. Ca. 1860's |
Early Relay by LG Tillotson, NY. Ca. 1860's. |
L.G. Tillotson, 26 Dey St, NY. Ca. 1865-1867 |
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| Acoustic Base Sounder by Montreal Telegraph Co. Ca. 1860's |
Another View of the Montreal Telegraph Sounder |
Charles T & JN Chester, NY. Ca. 1860's |
Very Early Altoona Shops Sounder. Altoona, PA. Ca. 1860s |
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| Another View of the Altoona Shops Sounder |
Knox & Shain Relay. Ca. 1860's |
Shawk & Barton, Chicago. Ca. 1868 |
A Canadian Acoustic Base Sounder by Dominion Telegraph Co. Ca. 1868 |
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| L.G. Tillotson, 11 Dey St, NY. Ca. 1868-1872 |
German Relay Made by Lewert. 1869 |
Interesting Sounder by Chester-Partrick & Co. Philadelphia. Ca. 1868-1872 |
Another View of the Chester-Partrick Sounder |
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| Top View of the Chester-Partrick Sounder Showing the Name Stamp |
Phelps Round Base Sounder. Ca. 1870 |
Phelps Sounder of the Style Usually Found on the Round Metal Base, But Mounted on a Wood Base |
Another View of the Wood Based Phelps Sounder |
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| Polar Relay by GM Phelps, Brooklyn NY. Ca. 1870 |
A Late Model Phelps Relay, NY. Ca. 1870 |
Another View of the Phelps Polar Relay |
Thomas Edison, NJ. Ca. 1870 |
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| Knox & Shain Sounder, Philadelphia. Ca. 1870 |
Another Version of the Knox & Shain Sounder on a Rectangular Base. |
Relay by W.H. Johnson, Louisville, Kentucky. Ca. 1870 |
Top View of the WH Johnson Relay |
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| An Unusual Tillotson Sounder With Steel Base. Ca. 1870 |
LG Tillotson Relay, NY. Ca. 1870 |
Early Tillotson Sounder. Ca. 1870 |
Another View of the Tillotson Sounder |
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| 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 |
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| Another View of the Tillotson Sounder |
Dominion Telegraph Box Relay, Canada. Ca. 1870 |
Interesting Sounder Made by Edison & Murray, Newark, NJ. Ca. 1870 (Sounder is Missing the Lever) |
Another View of the Edison & Murray Sounder |
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| An Unusual Drum Sounder by Watts & Co. Baltimore. Ca. 1870. Sound is Amplified by the Hollow Metal Drum (Smithsonian Museum) |
Top View of the Watts Drum Sounder. (Smithsonian Museum) |
Early Telegraph Sounder by Chester-Partrick & Co, Philadelphia. Ca. 1870. (Smithsonian Museum) |
Another Sounder by Edison & Murray |
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| Unmarked Sounder, Possibly Made by Edison & Murray. (Note the Captive Binding Post Nuts) |
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 |
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| 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 |
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| Note the Similarity to Sounders Made at Caton Instrument Shops, Whom Western Electric Was the Successor. |
Western Electric, Chicago. Ca. Early 1870's |
Ornate Round-Base Sounder by William Davis, Jersey City, NJ. Ca. Early 1870's (Smithsonian Museum) |
Another View of the William Davis Sounder (Smithsonian Museum) |
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| A 3rd View of the Davis Sounder Showing the Cylindrical Resonator Device (Smithsonian Museum) |
Bliss-Tillotson Single Coil Sounder With Miles Goodyear Patent, Chicago. Ca. 1872 |
Davis & Watts, Baltimore. Ca. Early 1870's |
Another View of the Davis & Watts Sounder |
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| Early Tillotson Sounder, NY. Ca. Early 1870's |
LG Tillotson Relay. Ca. 1870's |
Very Early British GPO Sounder. Ca. 1870's. (M6BRN, Mark Brundrit Collection) |
"Uncle Sam" Sounder. William Davis, Jersey City. Ca. Early 1870's |
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| Another View of the Uncle Sam Sounder |
Splitdorf Castanet Sounder Patent Model, 1874 |
James Partrick Sounder. Ca. Early 1870's (Gil Schlehman, K9WDY, Collection) |
An Early Partrick & Carter Sounder. Ca. Early 1870's (Gil Schlehman, K9WDY, Collection) |
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| Sounder and Camelback Key With Beautiful Engine Turning Finish. Cooperative Mfg. Co. Philadelphia. Ca. Early 1870's |
Relay Made by Cooperative Manufacturing Co, Philadelphia. Early 1870's |
Another View of the Cooperative Mfg Relay Showing the Name Stamp |
Another Canadian Dominion Telegraph Sounder. Ca. 1870's |
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| 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 |
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| 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. |
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| 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 |
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| 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 |
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| 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 |
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| Relay by Charles Williams, Boston. Ca. 1870's |
Another View of the Williams Relay |
Jerome Redding, Boston. Ca. 1870's |
Nickel Plated Sounder by Charles T. Chester, NY. Ca. 1870's |
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| LG Tillotson Repeater. New York. Mid-1870's |
Another View of the Tillotson Repeater |
JH Bunnell 1875 Patent Sounder. New York |
Tillotson Sounder With Bunnell 1875 Patent |
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| Close-Up of the Bunnell 1875 Patent (Patent Applied for in 1874) |
Partrick & Carter "Champion" Private line Sounder, Philadelphia. Ca. 1870's |
Top View of the "Champion" Sounder Showing the Bunnell 1875 Patent. (Patent Applied for in 1874) |
Partrick & Carter. Ca. 1870's |
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| Tillotson Stand-Alone Box Relay. Does Not Have a Key. Ca. 1870's |
Another View of the Tillotson Box Relay |
Partrick & Carter. (Bunnell 1875 Patent) |
Post & Co, Cincinnati Ohio. (Bunnell 1875 Patent) |
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| 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 |
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| 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 |
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| J.H. Bunnell, NY. 1877 Patent |
Austrian Relay by JM Ekling. Ca. 1870's. Note the Ivory Insulators |
Early British GPO Sounder With Galvanometer |
Small Relay by LG Tillotson, NY. Ca. Late 1870's |
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Another View of the Small Tillotson Relay |
An Unusual Telephone Receiver That Uses a Round Base Phelps Sounder. Invented by Amos Dolbear in 1879 (Smithsonian Museum) |
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