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Jacob's Staff = Log Periodic Antenna?
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These images have been chosen for their uniqueness. Subject matter ranges from historic events, to really cool phenomena in science and engineering, to relevant place, to ingenious contraptions, to interesting products (which now has its own dedicated Featured Product category).

Jacob's Staff image from "Comets, Popular Culture, and the Birth of Modern Cosmology" - RF Cafe Cool PicA decade ago, I featured a quilt made by Sara Schechner that depicted the 26-inch Alvan Clark telescope. She later contacted me about having learned of its appearance on RF Cafe. Sara is the curator of the Collection of Historical Scientific Instruments at Harvard University, and holds a PhD from Harvard. She wrote a book in 1997 entitled, "Comets, Popular Culture, and the Birth of Modern Cosmology." It includes an extensive collection of ancient drawings and etchings of astronomical events such as comets, meteors, super novae, and solar system conjunctions, as well as implications of such phenomena in significant world events. Astrologers made a pretty good living in the day by convincing rulers and potentates that they had privileged insight into the significance of such things.

While reading it, I ran across this etching (left) depicting "Archimedes (c.250 BC) beholding both [planets and comet] in his Jacobs Staff." The first thing that struck me in the image is that the Jacob's Staff looks an awful lot like a log periodic antenna. Compare the rendition to the log periodic antenna structure shown in the Wikipedia image (below left). The physical size suggests its use is designed for maybe the 900 MHz ISM band, or even higher bands. Could Archimedes actually be pointing a directional radio frequency antenna at the comet in an attempt to communicate with alien beings in a starship, rather than using it to determine the celestial coordinates of the object? Maybe aliens provided it to him ;-)

Log Periodic Antenna, Wikipedia - RF CafeLog Periodic Antenna

Jacob's Staff, Wikipedia - RF CafeJacob's Staff

According to Wikipedia's explanation of how the Jacob's Staff was used, "The navigator places one end of the main staff against his cheek just below his eye. He sights the horizon at the end of the lower part of the transom (or through the hole in the brass fitting) (B), adjusting the cross arm on the main arm until he or she can sight the sun at the other end of the transom (C). The altitude can then be determined by reading the position of the transom on the scale on the main staff. This value was converted to an angular measurement by looking up the value in a table."

OK, you might conclude given the context of the drawing that Archimedes was doing just that. However, note that the bottom of the picture seems to be missing. Well, with a little sleuthing in Cyberspace, I was able unearth the rest of the original picture (right). It appears to support my theory - what do you think?

Sara Schechner with her Alvan Clark Telescope Quilt - RF Cafe Cool Pic

This quilt, made by HAD (Historical Astronomy Division, of the American Astronomical Society) past chair Sara Schechner, is a copy of a well-known photograph of the 26-inch Alvan Clark telescope as first set up at the original USNO site in Foggy Bottom, c.1873. Simon Newcomb is at the eyepiece. Details of the quilt (size, length of time to make, where displayed, etc.) are hard to come by.



Posted December 14, 2022
(updated from original post on 4/26/2012)

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RF Cafe began life in 1996 as "RF Tools" in an AOL screen name web space totaling 2 MB. Its primary purpose was to provide me with ready access to commonly needed formulas and reference material while performing my work as an RF system and circuit design engineer. The World Wide Web (Internet) was largely an unknown entity at the time and bandwidth was a scarce commodity. Dial-up modems blazed along at 14.4 kbps while tying up your telephone line, and a nice lady's voice announced "You've Got Mail" when a new message arrived...

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