‘So, how far could they get, say, in the 1890s?’ Basic question to be able to answer. I’m put in mind of an astronomer friend, expert in quasars and black-body radiation, who blushed when she couldn’t tell a layman how far away Mars is.
If anyone asks you, say that in 1897 the Marconi system, in the hands of the army and navy, was good for two or three miles.
That means it was no longer an induction system. It was ground wave. ‘Even a mountain between the transmitter and receiver does not, it is said, prevent transmission[.]’ It’s not at all clear (and Marconi couldn’t say in the trans-Atlantic tests several years later) what the wavelength was. (We think we know, but that’s another post.)
Says who: ‘Topics of the Times,’ New York Times, May 26, 1897, p. 6.