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"Edison Day, October 21st"

Image: Thomas Edison standing next to an open box of tungsten lamps.
Blotter number 179-2; image number: LAR_B1792.

Text on blotter reads:
"Edison Mazda. More Light for Less Money."

"Edison Day, October 21st.
35th Anniversary of His Invention of the Incandescent Lamp."

The mythology surrounding Thomas Edison's lamp invention focuses on 21 October 1879 as the day of the invention. However, work by historians Robert Friedel and Paul Israel sheds new light on events at Menlo Park. Laboratory notebooks record an on-going series of experiments during this time and, "October 21, ..., came to an end without the dramatic success that subsequent accounts of the electric light's invention attributed to it." 

The following day Edison coworker Charles Batchelor recorded, "We made some very interesting experiments on straight carbons made from cotton thread." One of these experiments tested a lamp containing a simple length of carbonized sewing thread (lamp number 9 in a group of 11) that burned for fourteen and one-half, not forty, hours. This experiment told Edison and his team that they were close to the answer, and served to focus their research.  In early December they began to feel confident that they had achieved their goal.

Public relations needed something more dramatic though, and using October 21 to celebrate Edison anniversaries quickly became commonplace. The 35th anniversary noted on the above blotter occurred in 1914 and was used both as a promotional opportunity and an opportunity to honor Edison himself. Special commemorative lamps were sold, "Edison Day" parades were held and retrospective articles appeared in newspapers and magazines.

Perhaps the largest such series of celebrations occurred in 1929 for the 50th anniversary, known as "Light's Golden Jubilee." Many realized it might be Edison's last major anniversary (indeed, he died two years later) so a national celebration was organized. Events included the lighting of specially-made 50,000 watt light bulbs and the opening of the reconstructed Menlo Park lab on the grounds of Henry Ford's Greenfield Village in Dearborn, Michigan. 

    For additional information about the experiments at Menlo Park see: 
  • Robert Friedel and Paul Israel with Bernard S. Finn, Edison's Electric Light:

  • Biography of an Invention, (New Brunswick, NJ: Rutgers Univ. Press, 1986). "Dramatic success" quote is on page 100; Batchelor's "straight carbons" quote in on page 101. Robert Friedel worked on the the first iteration of the physical "Lighting A Revolution" exhibition in 1978-79. 
  • Photos from the Golden Jubilee celebration can be seen on the Smithsonian on-line exhibition Edison After Forty in the section, "Edison in His Eighties." 

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