Blake's transmitter
Date1881
Inventory Number8031
ClassificationTelephone
Subject
Maker
Francis Blake
1850 - 1913
Cultural Region
Place of Origin
Dimensions20.6 × 15 × 15 cm (8 1/8 × 5 7/8 × 5 7/8 in.)
Material
DescriptionA Blake transmitter developed by Francis Blake, Jr. of Weston, Massachusetts and patented in England on January 20, 1879 and in the United States on November 29, 1881. This transmitter was the Bell company standard transmitter, used through the 1880s.
The system uses a variable-contact transmitter, with a block of carbon mounted on a stiff spring resting against a piece of platinum mounted on a lighter spring. The lighter spring places the platinum in contact with the diaphragm. The electrical connection is through the platinum contact.
This device is an unusual European independent implementation of the instrument, using the Blake transmitter, a magneto bell and a switch-hook operated receiver.
A square wooden base with decorative molding on edges supports a wooden case with rounded top corners. A metal bell, held in place by an adjustment screw with a knurled edge and a spherical clapper are mounted on the top of the case. A black knob with knurled edge is located near the edge of the top of the case. Four binding posts are located on the left side of the case.
An additional four binding posts, a metal key and a switch-hook are located on the right. The switch hook is mounted on a pivot; its motion is constrained by a pair of leaf springs and a coiled spring. The top of the switch-hook arm has a flat piece of ivory-colored resin or other similar material as an insulator.
The front of the case is hinged, with a decorative turned edge, and a bowl-shaped mouthpiece is carved into the center of the front of the case. At the bottom of the bowl is a circular opening, through which the diaphragm may be seen.
When the door to the case is opened, the back of the diaphragm assembly and is seen, held by a mounting bracket on the door, as well as the door latching mechanism, three magnetic coils and the wire connections between the bell, the binding posts and the diaphragm.
Instrument is stamped on the top left front corner, "124"; top right front corner stamped, "B"; and on front, "BREVETE S.G.D.G."
The system uses a variable-contact transmitter, with a block of carbon mounted on a stiff spring resting against a piece of platinum mounted on a lighter spring. The lighter spring places the platinum in contact with the diaphragm. The electrical connection is through the platinum contact.
This device is an unusual European independent implementation of the instrument, using the Blake transmitter, a magneto bell and a switch-hook operated receiver.
A square wooden base with decorative molding on edges supports a wooden case with rounded top corners. A metal bell, held in place by an adjustment screw with a knurled edge and a spherical clapper are mounted on the top of the case. A black knob with knurled edge is located near the edge of the top of the case. Four binding posts are located on the left side of the case.
An additional four binding posts, a metal key and a switch-hook are located on the right. The switch hook is mounted on a pivot; its motion is constrained by a pair of leaf springs and a coiled spring. The top of the switch-hook arm has a flat piece of ivory-colored resin or other similar material as an insulator.
The front of the case is hinged, with a decorative turned edge, and a bowl-shaped mouthpiece is carved into the center of the front of the case. At the bottom of the bowl is a circular opening, through which the diaphragm may be seen.
When the door to the case is opened, the back of the diaphragm assembly and is seen, held by a mounting bracket on the door, as well as the door latching mechanism, three magnetic coils and the wire connections between the bell, the binding posts and the diaphragm.
Instrument is stamped on the top left front corner, "124"; top right front corner stamped, "B"; and on front, "BREVETE S.G.D.G."
Signedunsigned
Inscribedtop left front corner stamped: 124;
top right front corner stamped: B;
front: BREVETE S.G.D.G.
Curatorial RemarksOld tag: "Blake's Transmitter & Set" Old tag: "8031 Blake's Transmit." Card (broken): "Blake"s Transmitter & Set"
FunctionConversion of sound into electrical signals for transmission over a distance
ProvenanceJefferson Laboratory, Physics Department, Harvard University
Historical AttributesFirst commercial appearance 1878/79.
Rudolph Koenig
Date: circa 1863
Accessories: repeater (item 8000b)
Object number: 8000a
Jefferson Physical Laboratory, Harvard University
Date: circa 1877
Object number: 8006
