TELEPHONE

The Telephone's Development



The Telephone's Development

Introduction

Telephone comes from the Greek word tele, meaning from afar, and phone, meaning voice or voiced sound. Generally, a telephone is any device which conveys sound over a distance. A string telephone, a megaphone, or a speaking tube might be considered telephonic instruments but for our purposes they are not telephones.

These transmit sound mechanically and not electrically. How's that? Speech is sound in motion. Talking produces acoustic pressure. Speaking into the can of a string telephone, for example, makes the line vibrate, causing sound waves to travel from one end of the stretched line to the other. A telephone by comparison, reproduces sound by electrical means. What the Victorians called "talking by lightning."

Literature review

A standard dictionary defines the telephone as "an apparatus for reproducing sound, especially that of the voice, at a great distance, by means of electricity; consisting of transmitting and receiving instruments connected by a line or wire which conveys the electric current." Electricity operates the telephone and it carries your voice. With that important point established, let's look at telephone history.

Modern telephones use electret microphones for transmitters and piezoelectric transducers for receivers but the principle described is the same. Sound waves picked up by an electret microphone causes "(Kim, Thomas, 2007 )a thin, metal-coated plastic diaphragm to vibrate, producing variations in an electric field across a tiny air gap between the diaphragm and an electrode." A piezoelectric transducer uses material, which converts the mechanical stress of a sound wave upon it into a varying electrical signal(Liddell 2007 ).

Telephone history begins, perhaps, at the start of human history. Man has always wanted to communicate from afar. People have used smoke signals, mirrors, jungle drums, carrier pigeons and semaphores to get a message from one point to another. But a phone was something new. Some say Francis Bacon predicted the telephone in 1627; however, his book New Utopia only described a long speaking tube.

While Da Vinci predicted flight and Jules Verne envisioned space travel, people did not lie awake through the centuries dreaming of making a call(DeVito 2008 ). Who in the fifteenth century could have imagined a pay phone on the street corner or a fax machine on their desk? Telephone development did not proceed in an organized line like powered flight, with one inventor after another working to realize a common goal, rather, it was a series of often disconnected events, mostly electrical, some accidental, that made the telephone possible. I'll cover just a few.

Discussion

In 1729 English chemist Stephen Gray transmitted electricity over a wire. He sent charges nearly 300 feet over brass wire and moistened thread. An electrostatic generator powered his experiments, one charge at a time. A few years later, Dutchman Pieter van Musschenbroek and German Ewald Georg von Kleist in 1746 independently developed the Leyden jar, a sort of battery or condenser for storing static electricity(Cooper 2006 ). Named for its Holland city of invention, the jar was a glass bottle lined inside and out with tin or ...