By Asha Gage, IET Archivist

Sir William Armstrong, later 1st Baron Armstrong, was one of the most successful British industrialists and scientists of the 19th century. He turned his vision and inventiveness to his country residence, Cragside, which is situated in Rothbury in Northumberland. But this was no genteel country folly, Cragisde was Armstrong’s laboratory where he experimented with water power. In 1880 Cragside was the first house in the world to be lit by hydro-electricity.

Armstrong wrote a descriptive letter to the editor of The Engineer journal on 17 January 1881 shortly after he utilised Joseph Swan’s newly invented incandescent light bulbs in his home. From this detailed narrative we can hear Armstrong’s own words about the marvels of this new energy that he had harnessed from the lakes created on his grounds.

He begins by writing that the application of Swan’s bulbs were ‘successful’ and would be of interest to the readers as the case possessed ‘novelty’ not only because of the mode of lighting for domestic use but because ‘the derivation of the producing power was entirely new’. The brook lit the house and there was ‘no consumption of any material in the process.’

This is what we would recognise as green or renewable energy today but in the 19th century this was not as important, except to Armstrong, who understood that coal was a finite resource and was keen to explore the potential of water power.

In 1878 Armstrong had used a Siemens’ dynamo-electric machine, the motor being a turbine that gave off 6 horsepower, the distance from the house being 1,500 yards. Water from two of the lakes in his grounds dropped vertically creating the necessary pressure to power arc lighting that illuminated his picture gallery. However, the arc lamps were unsuitable and were replaced by Armstrong in 1880 with 45 incandescent lamps. These could be isolated by switching off the current from room to room so never having more than 37 lamps on at one time.

The Library was lit by eight lamps, four clustered in one globe of ground glass, suspended from the ceiling. Armstrong was not only one for renewable energy, he also repurposed fixtures within his home too. The remaining lamps were placed in globes ‘upon vases which were previously used as stands for duplex kerosene lamps.’ Armstrong continues to explain, the novel, yet hazardous, method for illuminating his Library,

“These vases, being enamel on copper, are themselves conductors, and serve for carrying the return current from the incandescent carbon to a metallic base in connection with the main return wire. The entering current is brought by a branch wire to a small insulated mercury cup in the centre of the base, and is carried forward to the lamp by a piece of insulated wire which passes through a hole in the bottom of the vase, and thence through the interior to the lamp on the top. The protruding end of this wire is naked, and dips into the mercury cup when the vase sets down. Thus the lamp may be extinguished and relighted at pleasure merely by removing the vase from its seat or setting it down again. “

Armstrong sang the praises of his friend, Sir Joseph Swan’s newly invented incandescent bulbs when he described them as having none of the ‘disagreeable attributes’ associated with arc lighting. Although brighter, arc lamps were not as serviceable in a domestic setting, their harsh glare not favourable in congenial gatherings or when gentle illumination was required as in the case of the gallery of paintings. Conversely incandescent lamps were steady and noiseless, a common complaint with arc lighting.
Combining poetical language with the need to convey their efficiency Armstrong portrays the lights in the passageways as presenting a ‘very beautiful star-like appearance’ that were not so bright as to pain the eye yet still powerful enough for lighting one’s way.

“In short, nothing can be better than this light for domestic use.”

Cragside was not only unique for its hydroelectric lighting, it was also a monument to modern living where Armstrong flexed his engineering and inventive prowess. By 1880 it had hot and cold running water, central heating, an internal telephone system, fire alarms, a hydraulic passenger lift, spit turner and dishwasher! All powered by the virtually cost-free, renewable energy source of water.
Cragside is now under the management of The National Trust and in 2006 the IET Archives were contacted to help advise on the electrical circuitry and decorative lighting. The printed letter from Armstrong was consulted to assist with restoring the home to its original splendour whilst adhering to modern electrical standards.

We think Armstrong would have approved of this progressive remodelling of his home.


‘Description of the Swan Incandescent Lamp, as used in a country mansion’ by Sir W M Armstrong. IET Archives NAEST 046/24

Rewiring Cragside (

‘The eccentric engineer’ J. Pollard IET Engineering and Technology Jan-Feb 2010

‘Cragside- the first home of hydro power’ IEE Review July/August 1989