Chapter 11: The Heliograph

One of my duties was to relay messages from Willis, a man stationed on Fish Butte. He was across the Locksaw River, 13 to 15 miles away as the crow flies, with a valley a mile deep between, bottomed by a raging river. He had no telephone; so we had to communicate by heliograph.

A heliograph is a mirror about 4" square which reflects the sun's rays toward the station desired. There is no limit of distance, as long as both points are visible. Willis talked with Graves Peak 80 miles away.

The set-up is as follows:

The silver is removed from the center of the mirror, about 1/8" dia. The mirror is pivoted vertically and horizontally, and a pointer which has vertical adjustment is located as shown. Looking through the unsilvered spot as a peep-sight and over the pointer to the station to be contacted, the assembly is clamped. In line with the direction desired, set up the shutter as close to the pointer as practicable. The mirror is then adjusted until the reflected light is directed on the white shutter. When the shadow of the unsilvered spot appears just over the pointer, we know that the ray is centered on our target. Frequent adjustment of the mirror is essential, and the alignment must not be disturbed.

As the Morse code has long and short dashes, a simplified code was adopted, in which all dashes are alike. The alphabet is divided into coordinates. The letter "Z" is omitted.

The dashes correspond with the numbers in the margin, the vertical column being given first. Thus the word "ham" would be indicated as follows:

--- --    - -    --- ---

We used the code the first day and had no trouble to speak of. We also had an abbreviated code -- i.e. A-D-G might mean "bring grub," etc. We had numbers which I may find later, but have lost.

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