Early forays In the mid 1850s Swan started to experiment with different emitting materials. He tried using strips of paper, which he packed in charcoal , and then baked in a kiln . After a great deal of trial and error, he managed to make carbon strips, that were strong enough to carry an electrical current, but thin enough to produce light without the huge amounts of power that his predecessor's solutions had required. However, it proved to be difficult to find a means of producing a strong enough vacuum to support this.
It wasn't until the early 1870s that improvements in vacuum pumps would prove capable of furnishing the levels of evacuation needed to proceed further.Even years later when he resumed his work, it still wasn't plane sailing. There would be other difficulties that had to be overcome. Firstly the carbon strips had a tendency to quickly wear away and snap. Secondly, as with Starr's lamp, the bulb's interior would become blackened after a while, obscuring the light produced. Basically carbon particles were being given off by the element, and deposits would build up on the glass. Swan postulated that if he could ensure greater levels of evacuation this blackening effect could be abated . If the purging of was complete, then there would be no residual air by which the carbon particles could be transported. Getting the vacuum to a lower level would prove difficult though, the methods he was using were pretty much state of the art for that time.2
Swan contemplated these two problems, and finally hit upon a way in which to overcome both of them at once. He attempted to dispel air from the bulb over two stages, first while the element was cold, then while a current was passed through it. The plan worked, and he concluded that the vacuum could be maintained and a high current applied to the strip without any detrimental effect on it. Likewise, the stronger vacuum meant that the strips weren't breaking (as the carbon was no longer wasting away). By mid 1878 he had a lamp that didn't blacken, and wasn't prone to snapping of the conducting medium, running for 12 to 13 hours.
In December of that year he demonstrated his invention, at a meeting of the Newcastle Chemical Society.Great, so if he managed to get it to work, then why does nobody recognise him for it? Well for all his technical prowess, Swan was more than a little naive when it came to dealing with the real world. His folly was that he only patented the means used to create his light bulb (i.e. the evacuation while a current was applied to the conductor and the carbonisation process) rather than the bulb itself. It was not simply lethargy on his part; he just felt that his demonstrations and published work on the subject would show that he had done the early running, if there was any dispute. Nevertheless, this move would eventually come back to haunt him
Meanwhile across the Atlantic, Edison had heard of Swan's research. unlike his British counterpart, he wasn't some part-time dabbler, he was a highly focussed professional, with a string of important inventions to his name, and a team of experienced engineers at his disposal. He put some of his best men to work on the task of improving Swan's rudimentary design. The legendary American inventor would eventually manage to create a lamp with a more sustainable vacuum, which would run for over 1500 hours of operation. Edison took out patents in both the united States and Great Britain late 1879, and when Swan started to turn out light bulbs from the factory he had established, he found himself in court. However this move was to backfire on Edison, he eventually lost the legal battle. They had effectively created a stalemate, each blocking the other from exploiting the huge potential market opening up before them. The best course of action appeared to be amalgamation.
Swan and Edison's companies
merged in 1883,
but their troubles were far from over.In 1885,
the problem of the light bulb patents
would flair up once more.
While Edison & Swan united Electric
wanted to enforce its monopoly
and stamp out the growing number
of companies that were infringing on its patents,
Edison's priority began to be questioned.
As Swan had made several public
demonstrations of his lamp before Edison's
patent had been filed,
it could be argued that the patent was invalid,
Swan would be regarded as what is termed
as a 'prior user'.
This offered a strong defence to anybody else who breached the patent. This whole mess could have been sorted out from day one if Swan had taken out the patent. Instead he had just part ownership in the company that produced the lamps, therefore only getting a cut of the money, which really should have been all his. To make matters worse it was soon to become apparent that he would have to give up the glory as well. The reason for this is as follows (so pay y attention). If the company was to retain the Edison patent, then it had to prove that Swan's work that pre-dated it didn't interfere. The best way for them to achieve this was to argue that the carbonated conductor Swan used in his lamps was not a filament (which formed the basis of Edison's system). The point was highly contentious (in fact there was no actual difference in the illuminating element that either parties had used), but somehow the British courts bought it. The patent was