Complex sentence: The first person to use the device to detect radio waves was a Frenchman named Edouard Branly, and Oliver Lodge popularised it when he gave a lecture in 1898 in honour of Hertz.
Split into simpler sentences: The first person to use the device to detect radio waves were Edouard Branly and Oliver Lodge. The latter popularised it when he gave a lecture in 1898 in honour of Hertz.