Jacob's Staff = Log Periodic Antenna?
Almost exactly two years ago, I featured a quilt made by
Sara Schechner that depicted the 26-inch Alvan Clark telescope. A couple months
ago, she contacted me about having learned of its appearance on RF Cafe. As it turns out she is the
curator of the Collection of Historical Scientific Instruments at Harvard University, and she holds
a PhD from Harvard. She wrote a book in 1997 titled, "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 (right) 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 dipole antenna. Compare the rendition to the folded structure
shown in the image from a Wikipedia article (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?
Comets, Popular Culture, and the Birth of Modern
Cosmology, by Sara Schechner Genuth
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
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."
Log Periodic Antenna
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?
This quilt, made by HAD
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.
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).
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Posted April 26, 2012
1996 - 2018
BSEE - KB3UON
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.
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