Heliography
(Communicating with Mirrors)
by James Riddle - KD7AOI
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Heliography (Communicating with Mirrors) by James Riddle - KD7AOI
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Prehistoric Heliographs?I received an e-mail from Tom Windes, an archaeologist with the National Park Service (UNM, Albuquerque), and another archaeologist, Tom Baker. They expressed the similarity between the army heliograph signaling They published a couple of articles about Chacoan signaling, but I decided to do a comparative study of the spacing and location of the Chacoan signaling stations with those of the U.S. Army's in 1886. I, like Windes and Baker believe the Chacoans may have used primitive form of mirrors, although only one they said has ever been noted from collections there, it being long lost. They published a couple of articles about Chacoan signaling, but I decided to do a comparative study of the spacing and location of the Chacoan signaling stations with those of the U.S. Army's in 1886. I, like Windes and Baker believe the Chacoans may have used primitive form of mirrors, although only one they said has ever been noted from collections there, it being long lost. Others have thought that the Anasazi Indians had signaling stations on prominent landmarks in the Chaco Canyon area, using fire at night and probably smoke by day. To this is added the possibility of mineral mirrors. Others have thought that the Anasazi Indians had signaling stations on prominent landmarks in the Chaco Canyon area, using fire at night and probably smoke by day. To this is added the possibility of mineral mirrors. As a result of these comments respecting possible ancient heliograph sites I decided to test the effectiveness of certain minerals for use as heliographs. I contacted Beth Boyd, a geologist at Yavapai College here in Prescott, Arizona and together we selected several mineral specimens for testing including schist, quartz, galena and copper pyrite crystals, and a piece of Muscovite Mica. Surprisingly good results were obtained with the mica sample composed of numerous flakes varying from 1/16" to 1/8" thickness, and the piece measured an average of 2.5" by 3.25". The longest range tested with the mica was 3.92 miles between the "scar" on the east side of Thumb Butte, and the parking lot at the north end of the "Prescott Resort", ironically owned by the Yavapai Indian Tribe. Both sites are adjacent to Prescott, Arizona. Ms Boyd also selected a smaller piece of similar mica for use at the resort. It being about 11:30am the sun was near its zenith allowing us to successfully signal one another. Interestingly, the mica outperformed a good quality 3" x 4" hand mirror, not quite so brilliant, but much easier to get "on target". This was due to the mica diffusing the reflected light providing a much wider field of reflection. It would have been much more difficult to reflect intelligible signals with a handheld flat glass mirror without mechanical aid such as is found in "modern" heliographs. I soon discovered it was possible to send a series of flashes that could be counted. At first they were doubled since I raised the mirror to (and above) the target and dropped it back down in the same plane, causing two flashes. Soon I learned to raise the mirror and when I was sure it had risen above the target I would swing it around in a circle to the right bringing it back to the beginning point. Using the mica as a heliograph for intelligent signaling is easy. Holding its edges with both hands within a few inches of the ground, and reflecting its light onto the ground in front of you and in line with the target, slowly turn it upwards so that its flash will catch the target and pass on above it and then circle back to starting point as described above. Also, you can use a rock or a bush just in front of you with its top just below the target to aid in catching the initial reflection before raising the reflection just above to flash the target. Using the mica as a heliograph for intelligent signaling is easy. Holding its edges with both hands within a few inches of the ground, and reflecting its light onto the ground in front of you and in line with the target, slowly turn it upwards so that its flash will catch the target and pass on above it and then circle back to starting point as described above. Also, you can use a rock or a bush just in front of you with its top just below the target to aid in catching the initial reflection before raising the reflection just above to flash the target. There is no reason while a series of prearranged signals could not be worked out using different numbers of flashes for different meanings. These could be repeated back by the receiving station for verification, if the sun's angle is such as to permit, or on the following day when conditions would permit. I have no idea whether the Chacoans used mica mirrors for signaling, but do understand that Muscovite mica mines do exist in New Mexico (see "Austin, G. S., Barker, J. M., and Bauer, P. W., 1990, Precambrian muscovite from the M.I.C.A. mine, Picuris Mountains, New Mexico: New Mexico Geological Society, Guidebook 41, p. 369��374"). The tests we performed prove that thin mica slabs can be used, very possibly at distances of ten or more miles depending on the size of the slab and even greater distances if the sun is low in the sky above and somewhat in line with the target. signaling, but do understand that Muscovite mica mines do exist in New Mexico (see "Austin, G. S., Barker, J. M., and Bauer, P. W., 1990, Precambrian muscovite from the M.I.C.A. mine, Picuris Mountains, New Mexico: New Mexico Geological Society, Guidebook 41, p. 369��374"). The tests we performed prove that thin mica slabs can be used, very possibly at distances of ten or more miles depending on the size of the slab and even greater distances if the sun is low in the sky above and somewhat in line with the target. Mica is fragile and would require extreme care to prevent its breaking. Such mirrors would have been greatly treasured, I believe, but destroyed rather than to have them fall into enemy hands. Also, because of their fragile structure it is doubtful they would survive the elements or burial; so finding one in any condition would be unusual, unless possibly in a cave. (I did recently find a nice, small piece of muscovite mica while hiking a trail northwest of Prescott, just lying there asking for me to pick it up, so maybe it is not so fragile after all. The piece measures about an inch by half inch and is in good condition. It certainly would be suitable for short distance signaling, probably a block or two. There obviously is more in the area.) Mica is fragile and would require extreme care to prevent its breaking. Such mirrors would have been greatly treasured, I believe, but destroyed rather than to have them fall into enemy hands. Also, because of their fragile structure it is doubtful they would survive the elements or burial; so finding one in any condition would be unusual, unless possibly in a cave. (I did recently find a nice, small piece of muscovite mica while hiking a trail northwest of Prescott, just lying there asking for me to pick it up, so maybe it is not so fragile after all. The piece measures about an inch by half inch and is in good condition. It certainly would be suitable for short distance signaling, probably a block or two. There obviously is more in the area.) I want to thank Beth Boyd of Yavapai College for assisting me in this research and her son Mackenzie who assisted her. They both learned how to successfully use the mica mirrors in a matter of minutes. We also were equipped with two-way radios, and used a GPS receiver to record locations, distances and bearings. James Riddle Please send me any evidence you might have on other prehistoric sites you have studied that may have used heliographic communications for inclusion in this report. James Riddle.
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