How did a Morse key help Guglielmo Marconi send wireless signals?

In the development of wireless telegraphy, Guglielmo Marconi utilized a Morse key as a control mechanism for the spark discharger at the sending end of his apparatus.1

By manually operating the Morse key, Marconi could interrupt or initiate the flow of electricity to the induction coil, which increased the voltage to create sparks. This action effectively modulated the radio waves, allowing him to transmit signals in the dot-dash patterns of Morse code. At the receiving end, these signals were detected by a coherer, which responded to the radio-frequency voltage by allowing current to pass and reproduce the transmitted Morse signals. This method was fundamental to his early experiments and his eventual success in bridging long distances, including the first transatlantic transmission in 1901.1234