Search results
Results from the WOW.Com Content Network
At the family home on Hammersmith Mall, he set up a complete subterranean system in a 175-yard (160 m) long trench as well as an eight-mile (13 km) long overhead telegraph. The lines were connected at both ends to revolving dials marked with the letters of the alphabet and electrical impulses sent along the wire were used to transmit messages.
An engine order telegraph, used to send instructions from the bridge of a ship to the engine room, fails to meet both criteria; it has a limited distance and very simple message set. There was only one ancient signalling system described that does meet these criteria.
It is a simple bar with a knob on top and an electrical contact underneath. When the bar is pressed down against spring tension, it makes a closed electric circuit. [4] Traditionally, American telegraph keys had flat topped knobs and narrow bars (frequently curved), while European telegraph keys had ball shaped knobs and thick bars.
The five-needle telegraph with twenty possible needle positions was six codes short of being able to encode the complete alphabet. The letters omitted were C, J, Q, U, X and Z. [32] A great selling point of this telegraph was that it was simple to use and required little operator training. There is no code to learn, as the letter being sent was ...
Tarr, Joel A., Thomas Finholt, and David Goodman. "The city and the telegraph: urban telecommunications in the pre-telephone era." Journal of Urban History 14.1 (1987): 38–80. Thompson, Robert Luther. Wiring a Continent: The History of the Telegraph Industry in the United States, 1832-1866 (1947) ends in 1866; emphasis on Western Union online
A Printing Telegraph Set built by Siemens & Halske in Saint Petersburg, Russia, ca.1900. The printing telegraph was invented by Royal Earl House in 1846. House's telegraph could transmit around 40 instantly readable words per minute, but was difficult to manufacture in bulk. The printer could copy and print out up to 2,000 words per hour.
An example of a very simple keyer is a single telegraph key, which used for sending Morse code. In such a use, the term "to key" typically means to turn on and off a carrier wave. For example, it is said that one "keys the transmitter" by connecting some low-power stage of the amplifier in a transmitter to its follow-on stage, through the ...
Earth-return telegraph is the system whereby the return path for the electric current of a telegraph circuit is provided by connection to the earth through an earth electrode. Using earth return saves a great deal of money on installation costs since it halves the amount of wire that is required, with a corresponding saving on the labour ...