Dear Friends,
The heliograph was indeed used for some time in military and
other settings. I have a most intriguing book about it and its
construction, use, and capabilities. It is remarkably simple, can be set
up (there being, of course sunshine -- so not so helpful here in western
Oregon!!) quickly, and reliably used to transmit information (via Morse
signals) over surprisingly long distances.
I don't know if it still is in print, but check out
Lewis Coe, Great Days of the Heliograph, 1987.
It was published privately by the author, whose address is listed as
115 E 113th Ave,
Crown Point, IN 46307.
I don't know if he is still there. He has published other things
about the telegraph in general. There are numerous pictures and a good
explanation in the text.
John
