KEY POINTS:
They are a collection of old light bulbs in an unprepossessing wooden box but without them, Thomas Alva Edison might never have claimed his proper place in the history books.
The 23 bulbs were the crucial evidence which clinched victory for the inventor in 1890 after a long-running dispute with a company that was trying to rip off his important breakthrough.
Long considered lost, they have been recently rediscovered in an American attic.
And they are now expected to make up to £300,000 ($854,000) at Christie's Landmarks of Science auction in London on Wednesday.
Laurence Fisher, the technical apparatus expert who could not believe his eyes when details of the find arrived in his inbox, said: "It's extraordinary.
"For many years, if you picked up a textbook on the history of the incandescent bulb, the trial is mentioned, but it would say the evidence that was produced was lost.
"The fact that it's remained together in almost perfect condition is staggering. It should not have survived."
Most of the lamps would even work as the filaments are intact - not that anyone should try - and the box comes with its original key.
Thomas Alva Edison obtained his American patent 223,898 on 27 January 1880.
A number of incandescent devices pre-date this including that of Sir Joseph Swan who received a British patent in 1878 and both Swan and Edison went on to market their respective devices on either side of the Atlantic.
But the United States Electric Light Company began marketing its own devices as if they were Edison's, using his patent number on the side.
This prompted the long-running challenge from the Edison Electric Light Company amid fears that the other company's actions were making patents valueless.
To uphold a patent, it is necessary for a person "schooled in the art" to make a working example of the invention according to its description.
But the United States Electric Light Company suggested it was impossible to make Edison's lights in the manner he had specified, thereby "justifying" their own version.
As the inventor was on the point of losing, John W Howell, his assistant, was sworn in to give testimony on 8 July 1890.
Pointing towards the wooden box which will be sold on Wednesday, Howell said, triumphantly: "I hereby produce the lamps."
Edison's patent was upheld and, following the trial, Edison's holdings became part of the newly-formed General Electric company under two of America's most influential investors, JP Morgan and Henry Villard.
Mr Fisher said that if the United States Electric Light Company had won, the detailed specifics of any patent would have been worthless.
"Edison was protecting his light bulb and his reputation," he said.
"If he lost, the United States Electric Light Company would have cornered the market and the light bulb that we're using now would have looked completely different."
In addition to the main interest of the box, one of the most interesting bulbs in it shows that Edison unwittingly invented a working diode 21 years before John Ambrose Fleming.
Other bulbs include examples made by Sir Joseph Swan and Hiram Maxim, another inventor who came up with the idea at about the same time as Swan and Edison.
Edison, Swan and Maxim all produced light bulbs which worked in different ways.
Swan and Maxim supported Edison in his court case because of the importance of resisting patent infringement.
Other items in the landmarks of science auction include Albert Einstein's first scientific essay, written when he was 16 and expected to make up to £500,000, and a first edition copy of Charles Darwin's On the Origin of the Species by Means of Natural Selection, in its original cloth cover, which has an estimate of £30,000 to £50,000.
- INDEPENDENT
