What is Helio in the 16th day? And can someone explain 'The Blues came up as our Machine Gunners' in the 17th day?
by ral104 moderator, scientist
Helio is a shortened version of heliograph - a simple device for signalling using reflected sunlight.
The Blues is the nickname of the Royal Horse Guards, one of the household cavalry regiments at the time.
Here is a image for a heliograph Link: https://www.flickr.com/photos/signalmirror/8669990143