Kendrick, KB1NCR, writes to the qrp-l mailing list:
I have been reading, and highly recommend, Signor Marconi’s Magic Box by Gavin Weightman (2003) – a history of Marconi’s inventions and competition with others in the turn of the century world of “wireless.”
In the brief chapter about the pre-WWI “free-for-all” pre-license amateur radio, he mentions this advertisement in Scientific American 1905. It is the first radio kit. Truly QRP, it guarantees a range of “at least one mile.”
Weightman acknowledges Early Radio History as a major resource during his research – it is a fantastic website for information about early radio.
By the way – thank god for continuous wave: spark gap transmitters sound terrifying.