In 1860, Swan created a crude bulb comprising a partially-evacuated glass bulb with a carbonised paper filament. It soon expired. The lamp which he demonstrated to the Newcastle Chemical Society in 1879 and at the Literary and Philosophical Society of Newcastle, in 1880, took advantage of Charles Henry Stearn's work on vacuums having an almost completely evacuated bulb with a carbonised thread filament. Little residual oxygen meant the bulb was practical - it glowed white-hot without catching fire or causing blackening.
There was great interest in Swan's experiments - the Swan Electric Light Company was established in 1881 and yet, on 24th December 1880, in a letter to Robert Spence Watson, Albert, Earl Grey pre-emptively wrote:
“If there is any chance of taking up shares in Swan's Light Cy I would be very much obliged to you if you wdremember me.”
Grey, A. Letter to Robert Spence Watson. 24th December 1880.
Spence Watson Papers SW 1/7/38
Yes so far as I know Cragside was the first house in England properly fitted with my electric lamps - I had greatly wished that it should be & when I told him so he [i.e. Lord Armstrong] readily assented. There had, previously to the introduction of the incandescent lamp into the house been an arc lamp in the picture gallery - that was taken down & my lamps were substituted, but was a delightful experience for both of us when the gallery was first lit up. The speed of the dynamo had not been quite rightly adjusted to produce the strength of current in the lamps that they required - the speed was too fast & the current too strong, consequently the lamps were far above their normal brightness; but the effect was splendid & never to [be] forgotten
Swan, J.W. Letter to Mr. Worsnop. 9th November 1897.
Manuscript Album, 147