Thomas Edison's Greatest Inventions
Thomas Edison's Greatest Inventions
How the iconic inventor's ideas shaped America
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Updated October 13, 2016.
The Phonograph 
Thomas Edison’s first great invention was the tin foil phonograph. While working to improve the efficiency of a telegraph transmitter , he noticed that the tape of the machine gave off a noise that resembled spoken words when played at a high speed. This led him to wonder if he could record a telephone message. 
So he began experimenting with the diaphragm of a telephone receiver by attaching a needle to it based on the reasoning that the needle could prick paper tape to record a message. His experiments led him to try a stylus on a tinfoil cylinder, which, to his great surprise, played back the short message he recorded, "Mary had a little lamb."
The word phonograph was the trade name for Edison's device, which played cylinders rather than discs. The machine had two needles: one for recording and one for playback. When you spoke into the mouthpiece, the sound vibrations of your voice would be indented onto the cylinder by the recording needle.
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Profile of Thomas Edison
The cylinder phonograph, the first machine that could record and reproduce sound, created a sensation and brought Edison international fame.
The date given for Edison's completion of the model for the first phonograph was August 12, 1877. It is more likely, however, that work on the model was not finished until November or December of that year since he did not file for the patent until December 24, 1877. He toured the country with the tin foil phonograph and was invited to the White House to demonstrate the device to President Rutherford B. Hayes in April 1878.
In 1878, Thomas Edison established the Edison Speaking Phonograph Company to sell the new machine. He suggested other uses for the phonograph, such as letter writing and dictation, phonographic books for blind people, a family record (recording family members in their own voices), music boxes and toys, clocks that announce the time and a connection with the telephone so communications could be recorded.
The phonograph also led to other spin-off inventions. For example, while the Edison Company had been fully devoted to the cylinder phonograph , Edison associates began developing their own disc player and discs in secret due to concern over the rising popularity of discs. And in 1913, the Kinetophone was introduced, which attempted to synchronize motion pictures with the sound of a phonograph cylinder record.
A Practical Light Bulb 
Thomas Edison's greatest challenge was the development of a practical incandescent, electric light. Contrary to popular belief, he didn't "invent" the lightbulb, but rather he improved upon a 50-year-old idea. In 1879, using lower current electricity, a small carbonized filament and an improved vacuum inside the globe, he was able to produce a reliable, long-lasting source of light. 
The idea of electric lighting was not new. A number of people had worked on and even developed forms of electric lighting. But up to that time, nothing had been developed that was remotely practical for home use. Edison's achievement was inventing not just an incandescent electric light, but also an electric lighting system that contained all the elements necessary to make the incandescent light practical, safe, and economical. He accomplished this when he was able to come up with an incandescent lamp with a filament of carbonized sewing thread that burned for thirteen and a half hours.
There are a couple of other interesting things about the invention of the light bulb. While most of the attention has been given to the discovery of the ideal filament that made it work, the invention of seven other system elements were just as critical to the practical application of electric lights as an alternative to the gas lights that were prevalent in that day.
These elements included:
The devices for maintaining constant voltage
Safety fuses and insulating materials
Light sockets with on-off switches
And before Edison could make his millions, every one of these elements had to be tested through careful trial and error, and developed further into practical, reproducible components. The first public demonstration of the Thomas Edison's incandescent lighting system was at the Menlo Park laboratory complex in December of 1879. 
Industrialized Electrical Systems
On September 4, 1882, the first commercial power station, located on Pearl Street in lower Manhattan, went into operation, providing light and electricity power to customers in a one square mile area. This marked the beginning of the electric age as the modern electric utility industry has since evolved from the early gas and electric carbon-arc commercial and street lighting systems.
Thomas Edison's Pearl Street electricity generating station introduced four key elements of a modern electric utility system. It featured reliable central generation, efficient distribution, a successful end use (in 1882, the light bulb) and a competitive price. A model of efficiency for its time, Pearl Street used one-third the fuel of its predecessors, burning about 10 pounds of coal per kilowatt hour, a "heat rate" equivalent of about 138,000 Btu per kilowatt hour. 
Initially, the Pearl Street utility served 59 customers for about 24 cents per kilowatt hour. In the late 1880s, power demand for electric motors dramatically altered the industry. It went from mainly providing nighttime lighting to becoming a 24-hour service due to high electricity demand for transportation and industry needs. By the end of the 1880s, small central stations dotted many U.S. cities, though each was limited in size to a few blocks because of direct current’s transmission inefficiencies.
Eventually the success of his electric light brought Thomas Edison to new heights of fame and wealth as electricity spread around the world. His various electric companies continued to grow until they were brought together to form Edison General Electric in 1889. 
Yet despite the use of his name in the company title, the inventor never controlled this company. The tremendous amount of capital needed to develop the incandescent lighting industry would necessitate the involvement of investment bankers such as J.P. Morgan. And when Edison General Electric merged with leading competitor Thompson-Houston in 1892, Edison was dropped from the name and the company became simply General Electric.
Motion Pictures
Thomas Edison's interest in motion pictures began before 1888, but it was English photographer Eadweard Muybridge ’s visit to his laboratory in West Orange in February of that year that inspired him to invent a camera for motion pictures. 
Muybridge had proposed that they collaborate and combine the Zoopraxiscope with the Edison phonograph. Edison was intrigued but decided not to participate in such a partnership because he felt that the Zoopraxiscope was not a very practical or efficient way of recording motion. 
However, he liked the concept and filed a caveat with the Patents Office on October 17, 1888 that described his ideas for a device that would "do for the eye what the phonograph does for the ear" -- record and reproduce objects in motion. The device, called a " Kinetoscope ," was combination of the Greek words "kineto" meaning "movement" and "scopos" meaning "to watch.”
Edison’s team finished development on the Kinetoscope in 1891. One of Edison's first motion pictures and the first motion picture ever copyrighted showed his employee Fred Ott pretending to sneeze. The major problem at the time, though, was that good film for motion pictures was not available. 
That all changed in 1893 when Eastman Kodak began supplying motion picture film stock, making it possible for Edison to step up the production of new motion pictures. To do this, he built a motion picture production studio in New Jersey that had a roof that could be opened to let in daylight. The entire building was constructed so that it could be moved to stay in line with the sun.
C. Francis Jenkins and Thomas Armat invented a film projector called the Vitascope and asked Edison to supply the films and manufacture the projector under his name. Eventually, the Edison Company developed its own projector, known as the Projectoscope, and stopped marketing the Vitascope. The first motion pictures shown in a "movie theater" in America were presented to audiences on April 23, 1896, in New York City.