Having gone through the earliest means of human communication, this week's episode brings forth replacements needed to satisfy the lapses of the acoustic string phones.
Human satisfaction is diminishing in nature. Satisfaction derived today may become unsatisfactory after a while. This is wholly due to humans' unending needs and wants. Little wonder why the acoustic string phones didn't last for long. Human communication needs began tending towards transmission over longer distances, hence came need for replacements. Devices which served as replacements were based on principles of telegraphy and could transmit messages up to 13 miles, which was about 26 times the operating range of acoustic string phones.

Telegraphy, originally coined from two Greek words; "tele" meaning remote and "graphein" meaning to write, roughly translates as remote writing, but more explicitly refers to very long distance transmission of textual messages without the presence of any physical message-bearing object to aid transmission. Textual messages are coded before transmission and decoded at reception points. Thus, both sender and receiver have prior knowledge of encoding technique to be used for message sending. Although varying encoding techniques were used at the discretion of various telegraph inventors, the widely used encoding technique was the Morse's Code developed in 1837 by Samuel Morse and his assistant.

Encoded texts are transmitted via various media. Initial means of telegraphy was the electrochemical means developed by Francisco Salva Campillo in 1804. The electrochemical telegraph employed Alessandro Volta's voltaic pile to pass electric current through electrically conducting chemical solutions in a sequential manner. As many wires as the amount of letters of alphabet and numerals are employed for the transmission. Each wire represents a letter or numeral. Passage of electric currents through the wires gives rise to varying bubbling signals in the solution and are interpreted by the telegraph operator. The presence of at least 36 wires in the voltaic pile made this type of telegraph rather cumbersome and clumsy in structure. This constituted the major setback of the electrochemical telegraph. Clumsiness in structure led to introduction of Electromagnetic (EM) Telegraph.

The EM telegraph employed four basic principles for operation. The first being the production of galvanic currents by chemical actions, demonstrated by Alessandro Volta (1800). Next principle was the ability of the galvanic currents to produce a magnetic field, thus being able to deflect unmagnetized needles. Also, principle of temporary magnetization of soft iron core when wound with energized wires, established by William Sturgeon (1825) and lastly, the Ohmic law stating the proportional relationship between the potential differences across ends of a conductor and the electric current flowing through such conductor. These four principles form the basis for operation of an electromagnetic telegraph. The EM telegraph circuit consists essentially of a conductor wound around a soft iron core, a source of galvanic current, galvanometers, a transmitter and a receiver. The transmitter itself consists of keys which represent code letters to be transmitted. Striking a key on the transmitter closes the circuit, causing current to flow and induce a magnetic field around the soft iron and also causing deflection of the needle of the galvanometer. The degree of deflection of the needle corresponds to certain code letters, which are then interpreted.

Independent researches where carried out by various scientists in different locations at about the same time, on the EM telegraph. This makes it difficult to attribute the works of electromagnetic telegraph to a single person. Amongst others, there are scientists such as Baron Schilling (1832); Carl Friedrich Gauss and Wilhelm Weber (1833) and; Samuel Morse (1837), who all contributed to the EM telegraph. Morse's model was of most impact, the most built upon model. This was due to the ability of these model to record its transmitted messages. It was one of the few telegraphs to be patented.

In the mid 19th century, out of human inquisitiveness came the desire to combine techniques of the acoustic phones and telegraphy. This gave a whole new dimension to the history of telephone. Further details of the result of this combined techniques would be next in series. Do make it a date next week as the TELEPHOLUTION series continues....many thanks for viewing!

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