This section deals with some inventors and inventions that changed our lives. I suggest using this section as a reference to have students begin working on their individual or group projects.
Georges Leclanche (1839-l882) developed the first dry cell battery. He really conceived of the idea of making electricity portable. His work led the way for development of hearing aids, cameras, electronic calculators and other inventions.
Students can research through many of the available resources listed to find experiments and demonstrations they may wish to do from recreating Morse's telegraph to making an alarm, quiz game or lighting a small house. (See lesson plans)
Samuel F.B. Morse is an interesting individual because he was primarily a portrait painter and one of the founders of the National Academy of Design. He became interested in electricity when he took a few courses at Columbia College. Morse renewed his interest in electricity while on a trip home from Europe. He worked out a plan for his idea of a telegraph and worked with an inventor named Page to design his device, which could send and receive code mechanically. Ever since Stephen Gray had shown that you could transmit electricity over wire and Oersted's discovery of electromagnetism there had been interest in researching a new kind of communication. Morse worked and Page worked on the idea for years. It was not until May 24,1844, that Morse finally finished constructing a line between Washington D.C. and Baltimore, Maryland. On that day the now famous message "What hath God wrought" was transmitted from Washington to Baltimore and then repeated by the operator in Baltimore back to Morse.31
Thomas Alva Edison (1847-1931) is one of America's foremost inventors. He is best known for his invention of the incandescent lamp. This lamp works by giving off light from a burning filament. While the principle of the burning filament was well known it was not considered practical because the filament usually burned out very quickly. Edison and his team took nearly a year to find a material that would burn for longer than a few minutes. Through this experimentation he also found that if the bulb had little air in it the filament burned longer. Edison also developed a better pump to help in trying to form a vacuum in the lamp. Among his dreams was a wish to electrify every home and factory in America. One mistake that Edison made was his reliance on direct current. He believed that alternating current was too dangerous.32
George Westinghouse (1846-1914) was one man who disagreed with Edison. Westinghouse had made a fortune from his invention of compressed air brakes for railroad cars. He then went into the electricity business. Westinghouse had bought a patent for a transformer from William Stanley. His transformer showed that you could transmit current by stepping up the volts from 500 to 3,000 from the generating station. Then you would step the voltage down at the other end back to 500. Stepping up the voltage was a more efficient way of transmitting current.33
The decision about AC or DC was fought by Edison and Westinghouse because there was a lot of money riding on which method was chosen. It wouldn't be just electrifying homes but selling generators and motors to factories. The question was finally settled by the work of another inventor Nikola Tesla. Nikola Tesla (1856-1943) was born in Croatia, which was once part of Yugoslavia. Tesla had only two years of engineering college but he was brilliant. He worked mostly with AC transmissions, AC motors and radio communications. Tesla worked for Edison but when he told Edison about his idea for an AC motor Edison tried to discourage him. After all Edison was in favor of DC transmission. However, Tesla believed in his idea and left Edison's lab. Westinghouse heard of Tesla's work and hired him. Tesla came up with the AC motor. Everyone but Edison agreed that it was superior to the DC motor. Even the company Edison had started, Edison Electric Company chose AC. This company is now General Electric.34
The transmission of information over the wires of a telegraph by Samuel Morse led to innovations of other kinds in the world of communication. If sounds could be transmitted why not the human voice. Alexander Graham Bell (1847-1922) was not the sole inventor of the telephone. Earlier scientist had written about this device that would be able to transmit the human voice. However many of their devices could not reproduce human speech accurately. On February 14, 1876 a man name Elisha Gray filed for a patent for a telephone. On that same day Alexander Graham Bell also filed for a patent for a telephone. Each man had worked independently of the other and filed for a patent without knowing about the other.35
Guglielmo Marconi (1874-1937) was an Italian inventor best known for his contributions for radio. After the discovery of electromagnetic waves, Marconi tried to utilize them for communication. After experimenting for several years he was able to send messages without wire over a distance of about a mile. By 1901 signals could be sent over longer distances. Marconi had developed the first radio.36