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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| The Marean Repeater Made by Partrick & Carter, Philadelphia. Ca. 1880 (Smithsonian Museum) |
The Marean Repeater Was Invented by Morell Marean , the Manager of the Western Union Office in Washington DC in 1880 (Smithsonian Museum) |
Western Electric Split-Anvil Sounder. Ca. Early 1880's |
California Electrical Works, San Francisco. Ca. 1880 |
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| Ornate Sounder by JH Longstreet, NY. Ca. 1880 (Smithsonian Museum) |
Early Western Electric Repeater. Ca. 1880 (Smithsonian Museum) |
Sounder by Post & Co, Cincinnati Ohio. Ca. 1880 (Gil Schlehman, K9WDY Collection) |
Top View of the Western Electric Repeater (Smithsonian Museum) |
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| An Early German Sounder by R. Wasserlein, Berlin. Early 1880's |
Another View of the Wasserlein Sounder |
Altoona Shops Cain Sounder. Ca. 1881 |
Another Sounder by Post & Co, Cincinnati. Early 1880's |
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| Relay by Post & Co, Cincinnati Ohio. Early 1880's |
JH Bunnell Sounder With 1882 Patent Base. |
A.B. Lyman, Cleveland, "Bullnose" Sounder. Ca. Early 1880's |
Another View of the Lyman Bullnose Sounder |
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| A Nickel Plated Lyman Bullnose Sounder |
Stearns & George, Boston. Likely a Reseller of Instruments, Not a Maker |
Unmarked Western Union Style Relay |
Another View of the Unmarked Relay |
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| Early Repeating Sounder. Maker Unknown. Ca. Early 1880's (Smithsonian Museum) |
Top View of the Repeating Sounder (Smithsonian Museum) |
Canadian Relay, Possibly Made by Dominion Telegraph. Early 1880's |
Partrick & Carter, Philadelphia. Ca. Early 1880's |
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| Small Sounder With No Markings. Maker Unknown |
Another View of the Sounder Showing the Small Size |
Some Components of This Sounder are Similar to Parts of Sounders Made by Partrick & Carter |
Another Unmarked Sounder, Probably the Same Maker as the Previous Small Sounder |
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| The Binding Posts of This Sounder Are Similar to Those of Partrick & Carter Sounders |
William Davis Vertical Sounder, Jersey City. Ca. 1883 |
The Davis Vertical Sounder With the Metal Cover Removed |
Gilliland Drum Sounder. Made by James Gilliland, Indianapolis Indiana Ca. 1885 |
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| Another View of the Gilliland Drum Sounder |
Viaduct Mfg, Baltimore. Ca 1880's |
P.B. Delany Sounder, NY. Ca. 1880's |
An Unusual Single Coil Relay by PB Delany, NY. Ca. 1880's (Smithsonian Museum) |
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| Sounder Marked Geo. H. Wells. No Record of This Maker. Ca. 1880's. (See His Matching Straight Key on the Post-1880 Landline Keys Page) |
Western Electric Box Relay, Chicago. Ca. 1880's |
Sounder Marked Chicago Telegraph Supply Co, Chicago. Likely Made by Western Electric. Ca. 1880's |
Interesting Relay made by JH Longstreet, NY. Ca. 1880's |
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| Small Unmarked Relay. Likely Made by LG Tillotson or ES Greeley, NY. Ca. 1880's |
Another View of the Small Unmarked Relay |
JH Longstreet Sounder, NY. Ca. 1880s |
Jerome Redding, Boston. Ca. Late 1880's |
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| New Haven Clock Co. Sounder. Ca Late 1880's |
Close-Up of the Brass Nameplate Button on the New Haven Clock Co. Sounder |
New Haven Clock Co. Repeating Sounder |
New Haven Clock Co. Relay. Ca. Late 1880's |
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| National Electric Mfg. Co. Sounder, NY. Late 1880s |
National Electric Mfg. Co. Relay.. Late 1880's |
Close-Up of the Name Button on the National Electric Relay |
Lewis & Fowler Mfg. Brooklyn NY. Ca. 1886-1887 |
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| Altoona Shops Sounder. Altoona, PA. Ca. Late 1880's |
C.H. DuBois, NY. Ca. Late 1880's |
British GPO Sounder. Ca. Late 1880's |
Sounder by Standard Electric, Louisville, KY. (Matching Sounder for the Biggs Key) |
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| The Standard Electric Sounder Has an Unusual Single-Piece Frame and Anvil |
British GPO Phelps-Style Sounder. Ca. 1880's |
E.S. Greeley Relay, NY. Ca. Late 1880's |
E.S. Greeley Pole-Changer Relay. Pat. 1888 |
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| Another View of the Greeley Pole-Changer Relay |
ES Greeley Polar Relay. Ca. Late 1880's |
JH Bunnell Repeating Sounder, NY. Ca. Late 1880's |
A.B. Lyman "Rock Bottom" Sounder, Cleveland. Ca. 1890's |
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| A.B. Lyman Leaf-Spring Pivot Sounder, Cleveland. Ca. 1890's |
Another View of the Lyman Leaf-Spring Pivot Sounder |
J.H. Bunnell Pole-Changer Relay. Ca. 1890's |
J.H. Bunnell Multiplex Relay. Ca. 1890's |
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| Another Bunnell Multiplex Relay |
Western Electric Repeating Telegraph, Chicago. Ca. 1890's |
Another View of the Western Electric Repeating Telegraph |
Western Electric Repeating Relay. Ca. 1890's |
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| Another View of the Repeating Relay |
J.H. Bunnell Repeater. Ca. 1890's |
Western Electric, Chicago. Ca. 1890's |
Greeley Pony Sounder, ES Greeley, NY. Ca. 1890's |
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| Another Version of the Greeley Pony Sounder With Different Spring Tension Design |
Greeley Victor Relay. Ca. 1890's |
An Unusual Sounder That Hits a Brass Disc on the Base. Unmarked but Possibly Made by Western Electric, NY |
Western Electric Tube-Lever Sounder. Ca. 1890's |
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| Another View of the Western Electric Tube Sounder |
Western Electric Pony Relay. Ca. 1890's |
Western Electric Pole-Changer Relay. Ca. 1890's |
Another View of the Pole-Changer Relay |
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| Close-Up of the Relay Mechanism |
Another Pole Changer Relay of Similar Design Made by a British Company, Possibly Silvertown |
Western Electric Tube-Lever Repeater. Ca. 1890's |
Another View of the Tube-Lever Repeater |
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| Milliken-Hicks Repeater. JH Bunnell, NY. Ca. 1890's |
Another View of the Milliken-Hicks Repeater |
A 3rd View of the Milliken-Hicks Repeater |
One Last View of the Milliken-Hicks Repeater |
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| Weiny-Phillips Relay by JH Bunnell, NY. Ca. 1890's |
Another View of the Weiny-Phillips Relay |
A Polar Relay by Western Electric Co, Chicago. Ca. 1890's |
Another View of the Western Electric Polar Relay |
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| E.S. Greeley Double Relay, NY. Ca. 1890's |
California Electrical Works Relay, San Francisco. Ca. 1890's |
Francis Hatmaker. Ca. 1900 |
A Western Electric Fire Alarm Relay. Ca. 1890s |
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| J.H. Bunnell Giant Sounder |
A Repeating Sounder by Bunnell Telegraph & Electric Co, NY. Ca. Late 1890's |
A Double-Relay Instrument That Was Actually Used as an Automatic Transmitter for Undersea Cable Telegraph Systems. Muirhead & Co. London. Ca. Early 1900's |
Close-Up of the Cable Transmitter Unit |
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| Pocket Watch Sounder. M&L.E.Co. NY (Manufacturers & Inventors Electric Co). Ca. Early 1900's |
The Back of the Pocket Watch Sounder Showing the Name Inscription |
The Pocket Watch Sounder Was Also Available With an Optional Built-in Tiny Key |
An Early Advertisement for the Pocket Watch Sounder, Which Was Called The Secret Sounder ! |
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| Belgian Relay. Ca. Early 1900's |
Belgian Drum Sounder. Ca. Early 1900's |
Austrian Relay. Ca. Early 1900's |
German Relay. Ca. Early 1900's |
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| British GPO Sounder in Resonator. Ca. Early 1900's |
Another British GPO Sounder in a Taller Resonator With Pinstriped Hood |
A View of the Back Side of the British Resonator Hood Showing the Nice Paint Job |
British Sounder by ATM in a Resonator Box |
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| Close-Up of the ATM Sounder |
Side View of the Resonator Hood Showing the ATM Name |
British GPO Sounder Made in the Style of an Early Western Electric Sounder |
British GPO Sounder With GPO 2617 Nameplate |
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| Top View of the GPO 2617 Sounder |
Sounder From a Fire Alarm Telegraph System. Gamewell Fire Alarm Telegraph Co, Boston |
Bunnell Polar Relay. Ca. 1900 |
Another Bunnell Polar Relay With Ornate Paint Trim |
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| A More Simplified Bunnell Polar Relay |
Western Electric Polar Relay. Ca. 1900 |
A Very Large Bunnell Polar Relay. Ca. 1900 |
Box Relay by Manhattan Electrical Supply Co. (MESCO) Ca. 1900 |
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| MESCO Double Relay. Ca. 1900 |
Bunnell Ghegan Patent Sounder. Ca. 1905 |
Bunnell Ghegan Sounder (Different Version) Ca. 1910 |
Western Electric "Gooseneck" Relay. Ca. Early 1900's |
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| Tillotson Sounder Converted to Spark Relay |
Foote-Pierson. Ca. Early 1900's |
Bunnell Mini Sounder. Ca. Early 1900's |
Bunnell Secret Sounder. Ca. Early 1900's (Mini Sounder Inside Headphone) |
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| Inside the Secret Sounder |
Bunnell Mainline Sounder, 1895 Patent. Ca. Early 1900's |
Another Version of the Bunnell Mainline Sounder |
Mascot Resonator Hood With Sounder |
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| Standard Resonator Hood |
Swing-Arm Resonator Hood |
The MESCO Adjustable Resonator Box on Stand. |
Close-Up of the Bunnell Sounder Inside the Resonator Box |
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| MESCO Sounder. Ca. Early 1900's |
Western Union Type 3-B Sounder. Ca. Early 1900's |
Western Union Type 3-C Sounder. Ca. Early 1900's |
Western Union Type 15-B Mainline Sounder. Ca. Early 1900's |
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| Western Union Type 21-A Relay. Ca. Early 1900's |
Western Union Portable Telegraph Set. Used by Telegraphers at Live Events Like Baseball Games, Horse Races, Etc. |
Another View of the Western Union Portable Set |
Western Union Type 7-A Sounder. Ca. Early 1900's |
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| British A.T.M. Relay. 1918 |
British Sounder by AW Gamage, London. Early 1900's |
British GPO Relay by Silvertown |
View of the Silvertown Relay Showing the Glass Cover Lifted |
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| Close-Up of the Silvertown Relay Contacts |
The Grout Sound Amplifier Horn for Telegraph Relays. Invented by Ransom Grout, Davenport Iowa, 1913 |
A Relay With the Grout Amplifier Horn Attached. With This Horn, the Operator Could More Easily Hear the Clicking Sound Generated by the Relay |
A Frequently Seen Bullnose Sounder With No Markings. Possibly Used at Telegraph Training Schools |
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| Signal Electric Sounder, Menominee, Michigan. Ca. 1920's |
Signal Electric Relay. Ca. 1920's |
Australian Sounder. Post-1900 |
Another Australian Sounder. Post-1900 |
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| A Different View of the Aussie Sounder Showing the Maker's Marking |
Another Australian GPO Style Sounder |
Another View of the Australian GPO Sounder |
Later Model Relay With Strange Pivot. Maker Unknown |
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| A Newer Relay Made by Signal in Prague, Czechoslovakia. Post-1900 |
Relay by G.N.T. (Great Northern Telegraph Co.) Copenhagen Denmark. Post-1900 |
Art Deco Style Swedish Relay. Ca. 1920's |
Japanese Sounder Allegedly Destroyed by Shrapnel During WW2 |
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| Nameplate Indicates Sounder was Made by Youhin Seijoujo in the Year Taisho 3 (1915) |
A Very Late Japanese Sounder Made by Toubu Denki, 1950 |
Close-Up of the Toubu Denki Nameplate |
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