Leafing through my copy of "The Practical Telephone Handbook" (1912
edition) - as one does - I came across the description of a transmitter for
"Wireless Telephony". It consists of an alternator that generates 5A at 60V
at the carrier frequency (60kHz) coupled to the aerial via a tuned step-up
transformer. The "modulator" is a water-cooled carbon microphone connected
in the earthy lead of the transformer secondary. The best bit, though, is
that the alternator is driven by a steam turbine. I'd always heard of "steam
radio", I hadn't realised it actually existed!

David.