Design
Early voicepipes consisted of two cones, of wood or metal, one end shaped to fit the speaker's mouth, connected to the other which was flared to amplify the sound. Later designs of the voicepipe inserted a removable cork-mounted whistle, which could be sounded by blowing into the tube from the other end. On naval vessels, this created a distinctive sound associated with urgent intra-ship communication on old warships. The sound of the whistle would summon the listener, who would remove the whistle and answer the call.
Voice pipes could be used over distances as long as 300 feet (90 m). However, very long speaking tubes might use an electrical signalling device to indicate a call, as the large volume of air in the pipe would make it difficult to blow with enough pressure to sound a whistle at the far end. Despite this, a pipe with a larger internal diameter was desirable for longer runs as the signal loss is inversely proportional to the pipe's cross-sectional area.
Voicepipes have no switching mechanism and so, to provide multiple destinations, separate voicepipes with dedicated transit pipes have to be provided between all pairs of desired endpoints.
The technology continues to be used into the electronic age due to its reliability and low cost. Voice pipes are unaffected by a complete electrical power loss or by an Electromagnetic pulse. Warships built as late as the 1950s continued to incorporate voicepipes alongside more advanced technology.
Read more about this topic: Speaking Tube
Famous quotes containing the word design:
“To nourish children and raise them against odds is in any time, any place, more valuable than to fix bolts in cars or design nuclear weapons.”
—Marilyn French (20th century)
“If I knew for a certainty that a man was coming to my house with the conscious design of doing me good, I should run for my life ... for fear that I should get some of his good done to me,—some of its virus mingled with my blood.”
—Henry David Thoreau (1817–1862)
“You can make as good a design out of an American turkey as a Japanese out of his native stork.”
—For the State of Illinois, U.S. public relief program (1935-1943)