relay
Date: circa 1904
Inventory Number: 1997-1-0559
Classification: Relay
Subject:
User: American Telephone and Telegraph Company (1885 - 2005)
Maker: Western Electric Company (1881 - 1995)
Cultural Region:
Place of Origin:
Dimensions:
13.5 × 18.5 × 9.9 cm (5 5/16 × 7 5/16 × 3 7/8 in.)
Material:
DescriptionTelegraph apparatus mounted on a black ceramic base. The base has two layers, the top layer dusty and matte and the bottom layer shiny. There are three flat screws, for connection to a battery, along the left edge of the base. There are also two pairs of flat screws along the back edge of the base, one near the left and one near the right. In the center of the base are four black metal cylinders -- two larger and two smaller -- all connected on the right by several black metal bars. There are brass coils extending down from several of these bars to the base. Two thicker brass coils extend from the bars to an upright piece of brass at the right edge of the base, adjustment knobs on the other side of the brass at the level where the coils connect. An arm extends out from this piece of brass and there is an adjustment knob on the end of it.
A brass bar runs beside the top of the cylinders toward the back of the base, with a rod extending down to the base at the end. A thin black metal plate sits just in front of the cylinders on the left. There is an L-shaped piece of metal toward the front of the base to the left of the cylinders with a double adjustment knob at the top. A piece of extends around all of the cylinders, toward the left, and touches down at the base.
A brass bar runs beside the top of the cylinders toward the back of the base, with a rod extending down to the base at the end. A thin black metal plate sits just in front of the cylinders on the left. There is an L-shaped piece of metal toward the front of the base to the left of the cylinders with a double adjustment knob at the top. A piece of extends around all of the cylinders, toward the left, and touches down at the base.
Signedon vertical brass plate: PAT. IN U.S.A. / NOV 15 04 / WESTERN / ELECTRIC / MADE IN U.S.A.
Inscribedon base: No 25 A
FunctionThis telegraphic instrument was used as a relay. It could be used to control the current flow between other telegraphic instruments and switchboards.
Curatorial RemarksTag: "FROM / American Telephone and Telegraph Co. / 195 Broadway New York, NY / No. 25-A. Neutral Pole- Changer Relay. Used as sending relay in Ridge Polar Duplex sets." Has a diagram with it (Drawn by DW?)
ProvenanceFrom the Physics Department, Harvard University. Lyman Laboratory. 12/12/1961.