The Franklin Institute logo Made possible by: Unisys

Edison's Lightbulb

Edison's brilliance

Thomas Alva Edison, born in Ohio on February 11, 1847, was one of the most well known inventors of all time. He spent a few of his early years in formal schooling, but he received most of his education at home. Thomas set up a laboratory in the basement of his family's Michigan home and spent most of his time experimenting. Edison's mother, Nancy, knew her son was fond of chemistry and electronics, so she gave him books to read on the subjects. One book explained how to perform chemistry experiments at home; Thomas did every one in the book.

A biographer of Edison once noted:

"His mother had accomplished that which all truly great teachers do for their pupils, she brought him to the stage of learning things for himself, learning that which most amused and interested him, and she encouraged him to go on in that path. It was the very best thing she could have done for this singular boy."
As Edison himself put it:
"My mother was the making of me. She understood me; she let me follow my bent."

In 1859, the Grand Trunk Railroad was extended to Port Huron, Michigan. Thomas got a job as a newsboy for the day-long trip to Detroit and back. Since there was a five-hour layover in Detroit, Edison asked for permission to move his laboratory to the baggage car of the train so he could continue his experiments there. This worked for a little while, until the train lurched forward and spilled some chemicals, setting the laboratory on fire. While working for the railroad, Thomas saved the life of a station official's child who had fallen onto the tracks of an oncoming train. As a way of thanking him for saving his child's life, the father taught Thomas how to use the telegraph.

Thomas became so good at using the telegraph that he got a job working as a telegrapher sending signals between the United States and Canada. He began experimenting with ways to improve the telegraph, which led to his invention of the automatic telegraph, duplex telegraph, and message printer. It was about this time that Thomas dedicated his life to being a full-time inventor.

Thomas Edison moved to New York and set up a small laboratory in Newark, New Jersey. He continued his work on the telegraph and his ideas also gave birth to the universal stock ticker. In 1875, Edison wanted to build a new laboratory in Menlo Park, New Jersey. His father Samuel supervised the construction of the new laboratory; it opened in 1876.

In the period from 1878 to 1880 Edison and his associates worked on at least three thousand different theories to develop an efficient incandescent lamp. Incandescent lamps make light by using electricity to heat a thin strip of material (called a filament) until it gets hot enough to glow. Many inventors had tried to perfect incandescent lamps to "sub-divide" electric light or make it smaller and weaker than it was in the existing arc lamps, which were too bright to be used for small spaces such as the rooms of a house.

Edison's lamp would consist of a filament housed in a glass vacuum bulb. He had his own glass blowing shed where the fragile bulbs were carefully crafted for his experiments. Edison was trying to come up with a high resistance system that would require far less electrical power than was used for the arc lamps. This could eventually mean small electric lights suitable for home use.

By January 1879, at his laboratory in Menlo Park, New Jersey, Edison had built his first high resistance, incandescent electric light. It worked by passing electricity through a thin platinum filament in the glass vacuum bulb, which delayed the filament from melting. Still, the lamp only burned for a few short hours. In order to improve the bulb, Edison needed all the persistence he had learned years before in his basement laboratory. He tested thousands and thousands of other materials to use for the filament. He even thought about using tungsten, which is the metal used for light bulb filaments now, but he couldn't work with it given the tools available at that time.

A look inside the bulb Edison's unique pointed-top design A close-up of the socket and inside of the light bulb.

A look inside the bulb; Edison's uniquie pointed-top design; and a close-up of the socket and inside of the bulb

One day, Edison was sitting in his laboratory absent-mindedly rolling a piece of compressed carbon between his fingers. He began carbonizing materials to be used for the filament. He tested the carbonized filaments of every plant imaginable, including baywood, boxwood, hickory, cedar, flax, and bamboo. He even contacted biologists who sent him plant fibers from places in the tropics. Edison acknowledged that the work was tedious and very demanding, especially on his workers helping with the experiments. He always recognized the importance of hard work and determination.

"Before I got through," he recalled, "I tested no fewer than 6,000 vegetable growths, and ransacked the world for the most suitable filament material."
"The electric light has caused me the greatest amount of study and has required the most elaborate experiments," he wrote. "I was never myself discouraged, or inclined to be hopeless of success. I cannot say the same for all my associates."
"Genius is one percent inspiration and ninety-nine percent perspiration."

Edison decided to try a carbonized cotton thread filament. When voltage was applied to the completed bulb, it began to radiate a soft orange glow. Just about fifteen hours later, the filament finally burned out. Further experimentation produced filaments that could burn longer and longer with each test. Patent number 223,898 was given to Edison's electric lamp.

Lamp Label

The Edison lamp from our Attic is dated January 27, 1880. It is a product of the continued improvements Edison made to the 1879 bulb. Even though it is over a hundred years old, this bulb looks very much like the light bulbs lighting your house right now. The base, or socket, on this 19th century lamp is similar to the ones still used today. It was one of the most important features of Edison's lamp and electrical system. The label on this bulb reads, "New Type Edison Lamp. Patented Jan. 27, 1880 OTHER EDISON PATENTS."

In the early 1880s, Edison planned and supervised the construction of the first commercial, central electric power station in New York City. In 1884, Edison began construction of a new laboratory in West Orange, New Jersey, where he lived and worked for the rest of his life. The West Orange facility is now part of the Edison National Historic Site, run by the National Park Service.

A view from the underside of the bulb.

Before he died in 1931, Edison patented 1,093 of his inventions. The wonders of his mind include the microphone, telephone receiver, universal stock ticker, phonograph, kinetoscope (used to view moving pictures), storage battery, electric pen, and mimeograph. Edison improved many other existing devices as well. From a discovery made by one of his associates, he patented the Edison effect (now called thermionic diode), which is the basis for all electron tubes. Edison will forever be remembered for his contributions to the incandescent light bulb. Even though he didn't dream up the first light bulb ever crafted, and technology continues to change every day, Edison's work with light bulbs was a spark of brilliance on the timeline of invention. At the very beginning of his experiments with the incandescent lamp in 1879, he said:

"We are striking it big in the electric light, better than my vivid imagination first conceived. Where this thing is going to stop Lord only knows."

Learn how to Make a Light Bulb by performing this experiment!