Raising an Obelisk: Part 3

I was determined to stick with this problem and to get an obelisk upright. My sculptor, builder, timber-framing wife, Laura, now became engulfed in my obsession. Laura and I made drawings and constructed and tested two concrete models. Mark Lehner and Julia Cort visited our studio for a demonstration. Surprising me, Mark enthusiastically supported the method. "This is Egyptian, archaic and simple," he said, "an idea I believe will work."

Shortly afterward, Julia Cort approved our construction calendar and offered funding to conduct a design development workshop inviting VMI's Grigg Mullen, the ever-ready traveling engineer with calculator, Jim Kricker, the New York millwright and rope and rigging expert with his 7,000-lb. dynamometer, as well as VMI cadet-on-leave Andy Smith and our own Wyly Brown armed with long-handled hoes. Laura and I were delighted with the new problem- solving firepower on our obelisk-raising team. Jim Kricker suggested a single rope sling around the obelisk, notably simplifying our thinking about stabilizing the tall, slender granite shaft during the raising. During a four-day workshop at our studio in Norwell, Massachusetts, we poured a 6-ft. concrete obelisk and built a 3x4x8-ft. sand pit and ramp holding a ton of sand to test and refine our idea.

The Aswan experience had alerted us to the importance of knowing the ropes. Jim Kricker inquired at the Cordage Institute in nearby Hingham and found suppliers for large quantities of Manila rope similar to that used by the Egyptians. Manila's natural fibers align with use, increasing its strength and diminishing its stretch. Using Kricker's dynamometer, we tested inch-and-a-half and 2-in. rope using the known load requirements for our raising. The amount of stretch in the rope under working loads was a factor in setting the height of the bearing wall so that the obelisk would land on or above the turning groove in the pedestal.

Reminding ourselves of the frustration when 170 pullers were unable to raise the stone from a 35-degree position on the ramp, we decided to find out what angle we needed for the final pull, when most of the sand would be out of the box. Grigg Mullen calculated pulling requirements for our proposed 25-ton stone at a number of different angles. He proposed a 75-degree angle, which would (for example) require a 37-lb. pull from each of 135 pullers. Such a light load would insure an easily controllable final pull. One Egyptian temple relief shown by Dieter Arnold depicts a symbolic erection of an obelisk with ropes by Ptolemaios XII Neos Dionysos. The angle of the obelisk in the relief is -- you guessed it -- 75 degrees.

The scene now moved to Milford, New Hampshire, where Dave McCormick, Fletcher Granite's yard supervisor, used two cranes to pull a 65,000-lb. (175 lbs. per cu. ft.) chunk of Kitledge gray granite out of Fletcher's quarry there. Then the scene moved to Fletcher's headquarters in Chelmsford, Massachusetts, where the inspired quarrymen took great pride in skillfully shaping the block into an obelisk measuring 36 ft. overall, including the 42-in. pyramidium, the topmost portion where the four sides taper sharply up to a point. The finished stone, 42 in. square at its base, tapered to 30 in. square at the base of the pyramidium and weighed 49,500 lbs., with its center of gravity equidistant from its four surfaces and 14 ft. 1 in. from the base.

Orthogonal drawing of 18-ft. granite bearing wall with stepped center section and plumb flankers. Shading lines indicate radiused portion of the pivot block above and 13-in.-wide turning groove in the pedestal below.

On August 24, 1999, Al Anderson of Blue Ridge Timber Framing arrived and hit the ground running (though he brought his fishing pole). Over the next three days he supervised the construction of the bearing wall, ramp and sand box. The bearing wall comprised large granite blocks in a three-bay system (drawing above), with the central bay offering a stair-stepped 75- degree face and the outer bays plumb to restrain the obelisk if necessary. Our ramp of crusher-run gravel ran in a gradual slope up to the rear of the bearing wall. Fletcher provided precast concrete blocks tenoned together to make up the walls of the box.

Around noon that same day, Jim Kricker drove up in his oneton flatbed truck, riding low on the axles with a spectacular load of hemp, some of it 3-in. Smiling from ear to ear, Jim had never in his life imagined a project that would require so much cordage. Using a simple lever, Jim and Grigg pre-stretched the rope to the load limits required to raise the obelisk. We developed a controlled brake-release method. Three 3-in. lines, each wrapped three times around the 12-in. oak brake logs at each end, provided six points of controlled release which would allow us to lower the obelisk slowly into position.

Was any timber framing involved in this project? It's a fair question. After leaving our dusty derrick dead in the desert, we hadn't used much wood to speak of. We did have a beautiful veneer-grade white oak pivot block (labeled in the drawing above), made by Wyly and my colleague Ellen Gibson, which provided a soft bearing surface for the obelisk to rotate around from horizontal to the 75-degree position against the bearing wall. Laura made the saddle, a tenoned structure with carved housings to hold the ropes wrapped around the butt of the obelisk. Wyly made a plumb square, based on the ancient Egyptian pattern shown in W. M. Flinders Petrie's Tools and Weapons (Constable & Co., 1917). We strapped this device to the side of the obelisk to observe its angle of rotation (facing page, lower right). Andy carved hardwood longhandled hoes (facing page, top), similar to those used by ancient Egyptians, to pull the sand through the sandbox portals. Our pedestal stone allowed for a 16-in. margin around the base of the obelisk. The turning groove was 5 in. deep, 13 in. wide.