Sorry For The Delay

It's taking me a while to get to the next research post. That's because I picked up a pair of assignments from Military History Quarterly - one on the "Heliograph" (think of it as a "sun telegraph" using mirrors to flash the sun's rays  - see below) and the other on "Operations Research" (a rather esoteric discipline that looks to improve how systems work). I'm pretty much done with the first, and should be able to get to the post about Historical Societies before starting the second. Thank you for your patience.

The photo shows an early U.S. Army heliograph. On the right is the mirror system that reflects the sun's rays. On the left is a shutter used to send Morse Code dots and dashes by blocking the flash from the mirror. The range on these instruments could be over 100 miles (on a sunny day). They were invented c. 1869, and in use by armies around the world until after World War I.