Wheatstone's telegraph transmitter
Date: 1845-1860
Inventory Number: DW0887a
Classification: Telegraph Transmitter
Subject:
Inventor: Sir Charles Wheatstone (1802 - 1875)
Maker: French
Dimensions:
9.2 × 14 × 17.5 cm (3 5/8 × 5 1/2 × 6 7/8 in.)
box: 14 × 26 × 19.7 cm (5 1/2 × 10 1/4 × 7 3/4 in.)
Accessories: part of a set that includes the receiver (DW0887b); loose front panel from base box
DescriptionAn alphabet-dial telegraph transmitter. The device consists of a short, square, 5-sided hollow box made of wood. The box has no bottom panel; the front panel has become detatched from the box and is a loose piece.
The box serves as a base that supports two brass binding posts along the top edge, and a horizontal dial with a notched edge, made of brass, held on a center spindle. Around the dial the letters of the alphabet are printed in black on a white background (minus the letter "W"), and three spaces marked "Alphabet," "Chiffers" and "+". The numerals 1-9 and 0 are printed below the letters A-J.
A contact sender, consisting of a curved metal handle with a wooden grip, is also fixed on the center spindle, and may be rotated .
On the underside of the base, a metal gear is set parallel to the dial on the top of the box. Adjacent to the gear, four metal contact strips are attached to the wood panel. Two are are in contact with the gear and are connected to the instrument's binding posts; one is positioned in such a way as to constrict the direction of gear rotation; the last one is positioned so that it is not in contact with the gear.
The box serves as a base that supports two brass binding posts along the top edge, and a horizontal dial with a notched edge, made of brass, held on a center spindle. Around the dial the letters of the alphabet are printed in black on a white background (minus the letter "W"), and three spaces marked "Alphabet," "Chiffers" and "+". The numerals 1-9 and 0 are printed below the letters A-J.
A contact sender, consisting of a curved metal handle with a wooden grip, is also fixed on the center spindle, and may be rotated .
On the underside of the base, a metal gear is set parallel to the dial on the top of the box. Adjacent to the gear, four metal contact strips are attached to the wood panel. Two are are in contact with the gear and are connected to the instrument's binding posts; one is positioned in such a way as to constrict the direction of gear rotation; the last one is positioned so that it is not in contact with the gear.
Signedunsigned
Inscribedprinted on dial: A-Z, minus W; Alphabet / Chiffers / +;
printed below letters A-J: 1/ 2 / 3 / 4 / 5 / 6 / 7 / 8 / 9 / 0
printed below letters A-J: 1/ 2 / 3 / 4 / 5 / 6 / 7 / 8 / 9 / 0
FunctionThis is a telegraph transmitter based on the invention by Charles Wheatstone in the 1840s, for transmitting signals that would be displayed as letters of the alphabet at the receiving end, which was thought at the time to be beneficial as it would allow less skilled operators than other methods.
The system is based on a circular panel inscribed with the letters of the alphabet and a few punctuation marks. The operator rotates a handle from letter to letter, always in a clockwise direction. The underlying mechanism emits an electrical impulse for every letter that the handle has passed over, an impulse that will in turn move a pointer by one letter on a similarly arranged circular panel (see DW0887b). In effect, the needle on the the receiver reproduces the movement of the handle of the transmitter.
Although originally designed to be relatively easy to operate, and remained in use for a decade or two, it was soon overshadowed by the more popular Morse, which allowed direct listening by the operators.
The particular example shown here appears to be of a relatively late date, and it was probably made in France.
The system is based on a circular panel inscribed with the letters of the alphabet and a few punctuation marks. The operator rotates a handle from letter to letter, always in a clockwise direction. The underlying mechanism emits an electrical impulse for every letter that the handle has passed over, an impulse that will in turn move a pointer by one letter on a similarly arranged circular panel (see DW0887b). In effect, the needle on the the receiver reproduces the movement of the handle of the transmitter.
Although originally designed to be relatively easy to operate, and remained in use for a decade or two, it was soon overshadowed by the more popular Morse, which allowed direct listening by the operators.
The particular example shown here appears to be of a relatively late date, and it was probably made in France.
Curatorial RemarksDW087a and b in same blue-board tray.
Primary SourcesA very good explanation of this telegraph can be found in:
Robert Sabine, The Electric Telegraph, London, 1867. pp. 82-84.Available in Google Books here.
Robert Sabine, The Electric Telegraph, London, 1867. pp. 82-84.Available in Google Books here.
ProvenanceAcquired in France, 1964.
