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.
Benjamin 6-lamp cluster adapter. brass medium-screw base with porcelain insulator, six brass candelabra screw sockets with plastic insulator, porcelain housing, stamped on top: “Benjamin-Pat.-May-17-1904”
Benjamin 4-lamp cluster adapter. brass medium-screw base with porcelain insulator, four brass candelabra screw sockets with plastic insulator, porcelain housing, stamped on top: “Benjamin-Pat.-May-17-1904”
A small, vertically mounted motor. Two-piece frame with 5/8" wide electromagnet coil at bottom and a 3-section armature mounted above. Pulley on one end of armature and commutator with make-shift wire and leaf-spring brushes on the other. Open frame construction, plate on top has been removed. No extant maker's marks.
A DC electric motor mounted on a wooden base, stamped on the side: "W.A. Ulary / Phila." Armature with two oil cups, dual pulley on one end and a commutator on the other. Two carbon brushes. Coil mounted on top above the armature. The manufacturer W.A. Ulary was located at 1018 Chestnut Street in Philadelphia in 1893. The founder was William Anst Ulary (7 September 1863 - 3 March 1943). Reference: Advertisement, Electrical World 22, (1 July 1893): xxx.
The donor reported that this "item was picked up in Norwalk, Conn. in a very old machine shop. I found it up in the attic. A quite old watchman, a former mechanic, told me he had installed it and removed it from the first tugboat in Long Island Sound to be lighted by electricity. He gave it to me to keep it from going to a junk yard after I had promised to give it a good home and see that it was properly cared for."
Early radio inventors used a variety of methods to detect radio waves. Those early detectors tended to be slow and cumbersome in operation and that limited transmission speed. In 1906, Lee de Forest built on the work of Thomas Edison and John Ambrose Fleming and invented an electron tube he called an “Audion.” His tube contained three internal elements: a filament, an electrode and a control grid. Today we call tubes of this type “triodes.” In 1907 De Forest received U.S. Patent #841,387 for his invention, one of the most important in the history of radio.