Page "Transformer" Paragraph 17

Lucien Gaulard and John Dixon Gibbs first exhibited a device with an open iron core called a " secondary generator " in London in 1882, then sold the idea to the Westinghouse company in the United States.

They also exhibited the invention in Turin, Italy in 1884, where it was adopted for an electric lighting system.

However, the efficiency of their open-core bipolar apparatus remained very low.