1912 Map of Great Lakes Canadian Radio-Telegraph Stations
on map for full-size version - Map curitosy
of Greg Szocs.
Even at full-size the map text is small so
it's reproduced here:
From left to right the station names are: Port Arthur 350 N.M. – 600M (500KHz), Sault Ste Marie
350 N.M – 600M, Tobermory 350 N.M – 600M and Midland 350 N.M – 600M
Notes on the map are:
N.M under station name shows range in nautical miles
M. under station name shows wave length in metres
All stations open permanently day and night during season of navigation and in daytime
during balance of year.
By 1914 a version of this map would show 4 additional stations at: Point Edward (Sarnia),
Port Burnwell, Toronto and Kingston.
More about these stations and their later history on Robert Mazur's (VA3ROM) website's VBA Page
Except as noted here most of the site's content is in the public domain.