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The NOVA Obelisk swinging through 15° to
vertical.
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Obelisk Raised!
by Peter Tyson
September 12, 1999
From the moment yesterday morning when I stepped into Fletcher
Granite, the quarry in Chelmsford, Massachusetts that was
graciously hosting NOVA's attempt to raise an obelisk, I was
on a mission, and not a very kind one at that.
It wasn't something I did intentionally, or even consciously.
But as soon as my boots crunched on the gravel path leading
into the quarry, I began searching for some chink in the
armor, some flaw in the design, some forgotten, seemingly
trivial detail that Rick Brown and his exacting team had
missed in their preparations for hauling the obelisk the last
15° to upright.
Partly it had to do with the fact that the first half of this
operation - getting the obelisk to 75° - had gone so
swimmingly that I began to have adrenalin withdrawal by the
end of the day. (Though it ultimately came up short, the
obelisk-raising attempt in Egypt last march did have its
moments of blood-pumping excitement.) I didn't want to suffer
that again, nor, I knew, did Julia Cort, who is making a film
for NOVA about this attempt. But mostly my suspicions arose
from having watched, in person and on film, two previous
attempts to erect an obelisk in Egypt come up short, and
knowing that those crews had put as much mental and physical
effort into their respective undertakings as this one had.
So, first I had to find out what Brown and Company had in mind
for the raising. Predictably, it proved as clean and elegant
in design as a Henry Moore sculpture: Four teams of 28
rope-pullers apiece would pull on four ropes stretching out
more or less in parallel from the tip of the obelisk to a
point about 100 feet away in the opposite direction to its
lean. Meantime, on the other side of the obelisk, Jim Kricker
and Al Anderson would carefully ease off on the braking ropes
running back to the big braking timbers, while Joel McCarty -
who heads up the Timber Framers Guild when he's not raising
obelisks—would keep his eye on two other ropes tied off
tautly on either side.
The pullers go at the ropes during one of several
test runs.
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Predictably, too, Brown's crew had carefully trained the
pullers, who hailed from both Fletcher Granite and the
Massachusetts College of Art. "If you want to play in my
sandbox, you have to convince me you can take instruction!"
belted out McCarty as he led training sessions soon after my
arrival on how to "pull with your fingertips."
But the team's conscientiousness only fueled my desire to turn
up something not thought of. I began probing:
"Joel," I said, sidling up to McCarty, "are you afraid the
pullers might just yank the obelisk right over?"
"Hell yes!" he said, grinning through his gray-flecked beard,
and then began reeling off figures. It will take 4,800 pounds
of pull to get the obelisk moving, he said, but that number
will drop off rapidly once the stone is underway. When it gets
to an angle of 83°, the obelisk's center of gravity will
pass over the point where the rock's butt end rests on the
edge of the turning groove, and the force on the braking ropes
will increase exponentially, since it will then equal the mass
of the obelisk times its velocity squared. Thus, for every
doubling of the obelisk's rotation speed, the force on the
braking ropes will increase four times. "If the gentlemen at
the braking ropes are sleeping," he said, "the obelisk will
accelerate at the falling-body rate of 32 feet per second per
second." McCarty went on and on, staring me down in a
perfectly kind way and smiling.
Okay, I thought, so they've worked out the figures if all goes
to plan, but what if one group of pullers pulls harder than
the others? I asked Rick Brown.
"If you'll look closely, you'll see we braided the four ropes
near the tip of the obelisk," he said, pointing. He didn't
need to explain: any out-of-sync pulling would have no effect
on the obelisk.
Could it tip to one side or the other?
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With the 100-plus rope gang behind them, Jim Kricker
(standing) and Wyly Brown check for movement in the
obelisk.
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Not likely, Brown said. Each of the two ropes out the side had
perhaps 1,000 pounds of tension in them, and both also had
swigging lines, which crew members could pull on to increase
tension if the obelisk started to favor one side or the
other.
I was getting concerned; my mission was endangered. Then Wyly
Brown told me he'd heard the critical angle was 86.5°,
not 83°. Aha, I gloated secretly, now I've got something
to work with. I announced the discrepancy to one of the timber
framers.
"Oh, it's 86 and a half now?" he said, laughing. "Ed must have
rejigged the numbers."
Not willing to give in so easily, I approached Ed Levin, the
mathematician-turned-timber framer who was in charge of
working out the engineering numbers.
"Oh, I recalculated it to account for the butt end resting in
the turning groove rather than right on the pedestal stone,"
he said, smiling like all the others. "Eighty-six-and-a-half
degrees is indeed the point where the obelisk will become
self-righting and"—he brought one hand down on the other
- "will want to go kerplunk." Confidence in his calculations
oozed from him like sweat.
Growing desperate, I walked up to Grigg Mullen, the
barrel-chested engineer.
"Grigg, couldn't something go horribly wrong?" I asked, hoping
my jocular tone might jar something loose.
"Well, it could spin out of control," he said. He put a meaty
hand on my shoulder. "Remember when you were in camp, and you
played that game where you tried to raise a bottle off the
ground with a wire, and it started spinning out of
control?"
No.
"Could happen here," he continued, and grinned. He couldn't
have looked more unconcerned.
"Of course, Mr. Murphy's always there."
That grin again.
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