overall: 6 in x 4 1/2 in x 7 in; 15.24 cm x 11.43 cm x 17.78 cm
Object Name:
telegraph key
cable key
submarine telegraph key
Date made:
ca 1880
Description (Brief):
Telegraph keys are electrical switches used to send coded messages that travel as a series of electrical pulses through a wire. Due to special difficulties in sending pulses through long underwater cables, so-called double-current keys were used. Instead of the short dots and long dashes of land-line telegraphs, submarine telegraphs sent positive pulses and negative pulses that made the receiver move right or left. The operator pressed one lever on the key to send a positive pulse and another to send a negative pulse. The code consisted of the sequence of left and right movements recorded on a paper tape.
