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.
The cables needed to transmit electrical power may seem simple but are actually complex technological artifacts. Modern cables inherit the lessons learned during more than a century of research and experience. This power cable was described by GE engineer William Clark in 1898 as follows: “1,000,000 [circular mil] cable composed of 59 wires, each .1305" in diameter, containing two insulated pressure wires each 2500 C.M. area, the whole insulated with saturated paper 5/32" thick and finished with lead 1/8" thick. This is a feeder cable for circuits not exceeding 2000 volts working pressure on Edison three wire circuits."
Submarine telegraph switch marked: "Muirhead & Co. Ltd / No. 38986". This switch was used on a submarine cable when the cable was worked simplex to allow switching between transmit and receive condition on the cable. As it switched between transmit and receive, it would ground the cable momentarily, thereby freeing the cable of any charge which could damage the receiving system. Hard rubber base and handle with four terminals and switch arm made of brass. Terminals marked: R, E, L and K. The switch is part of a submarine telegraph testing system, mounted on a black-painted base with another switch and a double key.
A double pole-double throw switch with two levers connected with an insulated block. This block is actuated by a brass handle, to switch between two sets of contacts. Six terminals across the back edge of the base, two of which are wired together, three others have separate cloth-insulated copper leads. The base is hard rubber. The switch is part of a submarine telegraph testing system mounted on a black-painted wooden base with another switch and a double key. Maker unknown, possibly Muirhead.
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.
The cathode rays passing through the aperture may be bent by an electromagnet. Made of clear glass, unmarked. Long glass tube with cylindrical bulb one end. Tube has two terminals, cathode plate and sealed exhausting tube at one end, midway is a metal cylinder with one closed end having an aperture. Bulb end has a disk target approximately the full inside diameter.