telegraph relay
Date1890-1920
Inventory Number1997-1-0608
ClassificationRelay
Subject
Maker
J. H. Bunnell & Company
1878-present
Cultural Region
Place of Origin
Dimensions8.8 × 16.9 × 9.6 cm (3 7/16 × 6 5/8 × 3 3/4 in.)
Material
DescriptionTelegraph relay mounted on a wooden rectangular base with rounded corners, the base sitting on a black piece of metal. Two brown cylinders (an electromagnet) sit in the middle of the base, connected in the back by a metal plate. An L-shaped piece of wood extends along the back and top of the magnet, turning into a semi-circular arc at the front. A screw with two adjustment dials goes through each end of the arc. A movable piece of metal stands in front of the magnet, wide in the bottom with a thin top extending up into the arc. A spring runs from a hook on the movable plate to a knob on the front of the base. Two binding posts stand to the right of the knob, and there are two more in the back corners of the base.
Signedbehind magnet: J.H. BUNNELL & CO. / NEW YORK U.S.A.
FunctionThis telegraphic instrument was used as a control relay. It could be used to control the current flow between other telegraphic instruments and switchboards. When a current flowed through the magnet, it would attract the metal plate in front. When the current ceased to flow, the plate would return to its resting position. The effect was that of opening and closing a switch.
Burnell Telephone and Electric Company
Date: circa 1905
Object number: 1997-1-0571
U.S. Electrical Supplies
Date: 1910-1920
Object number: 1997-1-0578
