Auction sheds light on Edison artefacts
Keys to the New Jersey lab where Thomas Edison invented the phonograph and some of the lightbulbs that he perfected have sold for more than 60,000 dollars (£47,000) at auction.
The keys fetched 10,625 dollars (£8,366) at the sale run by Heritage Auctions in Dallas, Texas. A bulb created by a German inventor who claimed to have invented the incandescent lightbulb before Edison was sold for 23,750 (£18,700), while a set of five Edison bulbs used in a court case sold for 30,000 (£23,622).
The items were acquired by Charlie Knudsen, 69, of Pittsburgh, and had belonged to his great-aunt who was married to one of the lawyers whose firm represented Edison in patent lawsuits.
Tags on some of the keys list the doors that they opened, including Edison's 1876 lab that became known as the "invention factory". Another key says "motor shed" and a third "shop".
Edison had applied for about 400 patents, including improvements to the incandescent bulb, before he left for New York City in 1882, said Kathleen Carlucci, director of the Thomas Edison Centre in New Jersey.
The lab itself was built by Edison's father about 30 miles north east of Trenton and was the world's largest in its day. Ms Carlucci said it was also "the first research and development facility".
The bulbs up for auction were part of a collection used in patent infringement lawsuits. "One bulb in particular was used in a case where he (Edison) was able to prove he had a patent," Mr Knudsen said.
After making lightbulbs commercially viable, the "Wizard of Menlo Park" turned his attention to New York City where he worked to develop an electric utility.
Squatters took over the abandoned Menlo Park property, raising chickens and crops, Ms Carlucci said, and locals held dances in the lab.
Today, Menlo Park is a national historic site and a state park. None of the original buildings remains, but a museum and education centre highlight Edison's accomplishments.
A 131ft memorial tower to commemorate his work on the lightbulb stands on the site. It was restored last year and its 14ft replica bulb shines in the night.