Artifact #7

DISCOVERED

After a Century in Darkness

Edison Trial Evidence Collection

"Edison Electric Light Company vs. United States Electric Light Company"

Tar-putty Lamp No. 7 is also labeled Tar-putty Lamp Exhibit No. 2 - marked 4454

"Edison Electric Light Company vs. United States Electric Light Company"

This Tar-putty lamp #7 is unique among the set of seven in that it has an obvious history of having been tested in its illuminated state for a considerable length of time. The #4454 hand written on the label is the "order" mark of Charles Deshler who gave testimony in the Edison trial about testing this lamp for 600 hours (source reference).

Note the patina of carbon soot built up inside the glass globe, the soot coating indicates the lamp was illuminated for an extended period. A unique phenomena has occurred in this lamp which is marked by two dark carbon halos on the inside of the glass. The two dark halo spots are 180 degrees opposed and are in line with the axis of the hole passing through the center of the filament helix, as if an invisible force was created along the center of the illuminated filament helix, a force that moved out in both directions from the helix and forced a greater amount of carbon soot to bombard the inner surface of the glass exactly in line with the helix axis. Keep in mind, the environment inside of this glass bulb is a vacuum. How did the carbon soot otherwise get directed to the precise two spots on the glass?

The phenomena that occurred inside this lamp is clearly extraordinary. Perhaps what happened here is the same phenomena observed by Edison in 1883, the phenomena that made him curious enough to explore and discover what was to become known as the Edison Effect, the phenomena that led to the discovery of the electron. These two dark halo marks are a great feature of this historic Edison incandescent lamp. This is the only lamp of its kind known to exist. This Lamp is one of the Tar-putty lamps found in the historic Edison courtroom collection.

There are seven Tar-putty lamps in this 22 lamp collection. This lamp has a carbonized seven loop coil filament of nearly uniform turns formed from a strand of Tar-putty approximately 0.015 of an inch in diameter. The cylindrical diameter of the helix filament is 3/16 inch, the axial width is 3/4 of an inch. The Tar-putty lamps in this collection were made by John W. Howell in 1890, made specifically as his evidence exhibit, the key exhibit in the Edison Patent Infringement Lawsuit - "Edison Electric Light Company vs. United States Electric Light Company."

2007 is this lamp's 117 th. Anniversary

Go To the Collection Group Exhibit

# # #