Telegraph relays amplified electrical signals in a telegraph line. Telegraph messages traveled as a series of electrical pulses through a wire from a transmitter to a receiver. Short pulses made a dot, slightly longer pulses a dash. The pulses faded in strength as they traveled through the wire, to the point where the incoming signal was too weak to directly operate a receiving sounder or register. A relay detected a weak signal and used a battery to strengthen the signal so that the receiver would operate.
This relay includes a marble base and was made by Charles T. Chester of New York City. The electromagnet coils are fixed but the steel core can be moved to adjust the strength of the magnetic field.
This telegraph register was made by Charles Chester of New York and displays the design typical of the mid 19th Century. Telegraph registers are electrically-activated printers that receive Morse code messages. The message travels as a series of electrical pulses through a wire. The pulses energize the register’s electromagnets which move a lever-arm holding a pen or stylus. A clockwork mechanism pulls a strip of paper across the pen or stylus, recording the message. Short pulses draw or emboss a dot, slightly longer pulses a dash. The sequence of dots and dashes represent letters and numbers.
This telegraph register is serial number 80 made by Charles T. Chester of New York. Set on a marble base, the unit was driven by a weight suspended by a string that passed through the hole in the base. Like a clock, the key was used to rewind the mechanism. Telegraph registers are electrically-activated printers that receive Morse code messages. The message travels as a series of electrical pulses through a wire. The pulses energize the register’s electromagnets which move a lever-arm holding a pen or stylus. A clockwork mechanism pulls a strip of paper across the pen or stylus, recording the message. Short pulses draw or emboss a dot, slightly longer pulses a dash. The sequence of dots and dashes represent letters and numbers.
Telegraph keys are electrical on-off switches used to send messages in Morse code. The message travels as a series of electrical pulses through a wire. The operator pushes the key’s lever down briefly to make a short signal, a dot, or holds the lever down for a moment to make a slightly longer signal, a dash. The sequence of dots and dashes represent letters and numbers. This key is referred to as a camelback due to the curved design of the lever.
This is almost certainly a reproduction. An XRF scan conducted on 5 February 2018 failed to indicate gold but found zinc and copper.
This object is a bronze copy of a gold medal presented to Cyrus Field in 1867. Field's daughter Isabella loaned the original to the Smithsonian from 1899 to 1903. Curator George C. Maynard described the original as "Four inches in diameter; edge 3/8 inch (.376) thick; weight twenty nine and fourteen-sixteenths ounces, avoirdupois. Inscription on reverse side; "By resolution of the Congress of the United States, March 2. 1867, to Cyrus W. Field, of New York, for his foresight, faith, and persistency in establishing Telegraphic Communication, by means of the Atlantic Telegraph, connecting the old with the new world.”
He identified the original medal as a “duplicate." He wrote, "The first medal struck was sent to the White House, to be presented to Mr. Field by the President [Andrew Johnson] and Field was notified to call for it. When he called the medal could not be found and, after some delay, another medal was struck and delivered to Field. Subsequently, upon clearing up the White House, for a change of administration the lost medal was found and given to Field. One medal is in the New York Museum of Fine Arts; this is the other."
Maynard wasn't certain which of the original medals was which. Isabella Field Judson wrote to Smithsonian secretary Langley on 25 July 1899: “I shall be glad to loan to the Institution the Gold Medal given by Congress to my father. I cannot say whether this one is the original or not, as there were two struck.”
A galvanometer with a glass cover and a copper plate above coil. Brass base and frame with indicator needle suspended. Glass cover has a hole in top to allow access to adjustment screw. Nameplate "Ruhmkorff a Paris". Two binding posts.
In 1825, Leopoldo Nobili (1784-1835), an Italian physicist, introduced a sensitive astatic galvanometer that could detect relatively small electric currents, and that was soon popular with scientists around the world. The Smithsonian purchased this example for use by Joseph Henry, the founding Secretary of the Institution. The "Ruhmkorff a Paris" inscription refers to Heinrich Daniel Ruhmkorff (1803-1877), a German instrument maker who established a shop in Paris in 1855. Reference: Leopoldo Nobili, Leopoldo, "Sur un nouveau galvanomètre présenté à l'Académie des Sciences," Bibliothèque Universelle 29 (1825): 119–125.
No extant maker's markings. Four cylindrical field magnets are arranged to energize two pole pieces. A ring-type armature is utilized with two curved commutator segments. Brushes are missing from this specimen. See US Patent 229191, Armature for Magneto-Electric Machines, issued 22 June 1880 to Charles A. Seeley. Claim pertaining to armature: an arrangement of wire radially in a disc to form the armature of a magneto-electric machine. A modification of Arago's disc. References: biography of Seeley, New York Tribune, Nov. 7, 1892; and N.Y. Tribune, March 28, 1867, "Electric Lighting."
Curator George C. Maynard noted: Seeley electric light dynamo, 1867. Devised and sale by Charles A. Seeley, who had an elaborate plan for utilizing the current generated by a dynamo to operate electric lights. It was exhibited to many persons in New York City, including Horace Greeley, who incredulously asked, "does he expect to grind out electric light by turning a crank?"