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.
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.