The modern society of electronic technology is a consequence involving the curiosity, persistence, and obstenacy inherent to the mankind as in a perennial search for a better way of life led men with inventive mind to deveolp many inventions and innovations. Among them the most representative ones are:

Alexander Gaham Bell
He electrified de human voice and by putting the spoken word on wires he invented the telephone. Bell was a Scotsman and was educated in the University of Edinburgh where he was born in April 3, 1847. In 1870 he immigrated to Canada. Following his father’s interest for teaching deaft-mute, in 1872 he became professor of vocal physiology at Boston University. He was deeply interested in the mechanics of speech, which led him into to the first experiments to develop an apparatus for the electrical transmission of the spoken words. In March 7, 1786, he was gratned with the patent nº 174,465 for the right of on the invention of the telephone. On a tour at the Philadelphia Centennial Exposition, the eperor of Brazil Dom Pedro Alcantara stopped to watch a demonstration of the telephone made by Bell, which was considered the first official recognation of the device.

Charles Cros
French, he was born in October 1st, 1842 in Fabrezan. A man who enjoyed the strife of life was poet, chemist, and painter. In April 1877 he presented to the French Academy of Sicence his project for a sound reproducer whose main conception was similar to the Edison phonograph. Therefore even considering his efforts he had any success to finalize his project as in February 1878 Edison was granted with the patent for the phonograph.

Emil Berliner
Was the main artisan for the development of the disc using the lateral cut phonograph disc method was born in 1851 in Hannover, Germany. In 1870 he sailed to the USA where he tried several jobs. As a self made man he installed a small laboratory where he conducted experiment in the original telephone device invented by Bell. In 1883, after many experiments based in the recording forerunners: Martinville, Cros and Bell-Tainter, he finally invented the foundation of the principle for recording the natural sound using the lateral modulation over a flat disc.

Hermann L. F. Von Helmholtz
Philosopher and physicist. He was born in August 31st 1821 in Potsdam, Germany. His parents were poor and turned him to study Medicine when he became associat in the Berlin Anatomical Museum. Later on he was assigned as professor of Physics at the University of Berlin when he was distinguished in Optics and Acoustics.
In 1836 he published his famous monograph: “Sensation of Tone” which was considered the most important work on Acoustics of the nineteenth century.
His researches were of utmost importance for the development to the theory of the propagation of electromagnetic waves, which fascinated his pupil Heinrich Hertz. Von Helmholtz has passed way in September 8, 1894 in Charlottenburg, Germany.

Leon Scott de Martinville
he was born in 1817 and was the inventor of the phonautograph, a crude machine whose operational principle was the forerunner of the diaphragm. He died poor and unknown in April 16, 1879 in Paris, France.

Michael Idvorsky Pupin
physicist and inventor of Serb ancestry immigrate to the USA in 1873. He was graduated from Columbia University in 1883 when he was appointed professor of Mathematics and Physics. In the field of Physics his studies led him to discovery the secondary X-Rays emission in 1892.
Since he was so motivated by his researches covered the wide field of telegraph, telephone and wireless Pupin’s crowning triumph was the invention of the telephone repeater as known as the Pupin coil, which greatly extended long-distance telephone connections.
Michael Pupin passed way in March 12, 1935 in New York City, USA.

Nikola Tesla

Fig. 360 - The Tesla coil.

Mathematician, he was born in Smiljan, Serbia in July 10, 1857. He studied mathematics, Physics and Mechanics at Gratz Polytechnic School and subsequently had two years at the University of Prague, where he studied Philosophy. During his course at Gratz he had been in touch with the original electrical dynamo invented by Z.T.Grammes when he proposed several technical modifications in order to simply the machine. In 1884 he immigrated to the USA when he developed innovations as the famous Tesla’s coil and several types of electrical motors for operation in alternate current.
In 1895 he invented a method for generating electricity using alternating current for transmission over long distances. He died at the age of 86 in January 7, 1943 in New York City, USA. Fig 360

Samuel Finley Breese Morse
American inventor and artist. He was born in April 27, 1791 in Charlestown, Massachusetts, and USA. Morse was graduated from Yale University in 1810 and he traveled to England to study arts. In 1825 he began work as professor of the Literature and Arts of Design at the University of the City of New York. In 1835 he built his first electrical telegraph instrument and transmitted messages from a distance of 500 mm based in a code comprising dash and dots. 30 years later after his first transmission the telegraph sounders that ticked on April 2, 1872, tapped sad news Samuel Morse had passed way.

Thomaz Alva Edison

Fig. 361 - Thomaz Alva Edison.

Was born in February 11, 1847 in Milan, Ohio, USA. Since his teens he had a great interest for science, mainly Chemistry. He was employed in the Grand Trunk railroad when he obtained the newspaper concession to sell newspaper on the trains. That enterprise supplied him funds for his first experimental works in his small home laboratory. In 1862, Edison became telegraph operator at the Port Huron railroad station, Michigan and in 1864 he invented the Duplex telegraph, which allows two-way messages simultaneously in just on wire transmission line. In the next years Edison worked as consultant engineer in several telegraphic companies when he sold several of his inventions.
As a famous man in 1870 he founded his laboratory in a place 40 km far away from New York known as Menlo Park. In October 18, 1931, all the light in America were turned off in a homage to the inventor of so many inventions and innovations, which among them the most famous ones are: the incandescent light, the phonograph and the mimeograph. Fig 361

Thomaz Young
Englishman, distinguished for intelligence and large universal culture. He was born in Milverton, England in 1773. Through his experiments he was the forerunner to reproduce the mechanical vibrations of a sound body. Later on other researchers as the German Weber and the French Lissajoux improved his pioneering work. Young died in 1829.

Wilhelm Conrad Röentgen
he was born in Lennep in 1845. For his discovery of the X-rays he was award with the first Nobel Prize of Physics in 1901. Roentgen was interested in other several scientific fields such as: piezo-electricity, polarized light electromagnetic rotation conductivity and heating in crystal. He died in February 10, 1923.