How do you move a 13-ton Egyptian sphinx? Penn Museum hopes to try it today.

As the old engineering school saying goes: Every journey of 300 feet begins with months of preparation, acquisition of four air dollies, and use of the right hydraulic gantry.

So it is that the Penn Museum, desiring to move its 13-ton red-granite sphinx from its longtime home in the Lower Egyptian Gallery to a new abode in the museum’s main entrance lobby, turned to Bob Thurlow, special projects manager, to work it all out.

Should all go according to plan — and Thurlow is confident that it will — the massive sphinx will move very slowly (on those air dollies) through an opening left by a removed door and window, and out onto a track supported by crisscrosses of steel trestle reminiscent of the rigging for the Wildcat roller coaster at Hersheypark.

The sphinx will then inch up inclines, around hairpin turns, and finally ease through another window, with inches to spare.

The tentative go time is 9 a.m. Wednesday, provided that weather conditions and a 7 a.m. soil test (for firmness) are favorable.

» UPDATE: The weather cooperated, and the Sphinx moved as planned. See it in motion here.

If not exactly a piece of cake, Thurlow is planning for a surprise-free, un-Wildcat-like ride.

“We’re all about people safety and artifact safety for this move,” he said the other day when discussing the preparations. Only the weather has been a question mark.

Is the museum concerned about the fate of its most famous holding, the largest sphinx in North America?

“I’ve spent a lot of time with the sphinx,” said museum Egyptologist Jennifer Wegner, who literally wrote the book on moving the Sphinx, The Sphinx that Traveled to Philadelphia: The Story of the Colossal Sphinx in the Penn Museum, co-authored with her Egyptologist husband, Josef Wegner.

“I’m probably a little less concerned than Bob is. I look at the past travels of the sphinx — it made it from Memphis, Egypt, all the way here 100 years ago without incident.”

The sphinx will go on public view in its new surroundings Nov. 16, when the museum unveils its new main entrance hall and other significant renovations.

The sphinx is being moved for multiple reasons, museum officials said. For one thing, with the ongoing renovation of the museum, its old home in the Lower Egyptian Gallery will soon be dedicated largely to funerary objects — mummies and the like. Curators do not consider this a particularly appropriate setting for a sphinx, which is a protective or guardian figure, warding off evil entities and welcoming the good.

The great half-columns that provided the sphinx with an atmospheric setting for decades in the lower gallery will be moved and assembled at full height for the first time in the Upper Egyptian Gallery. The completely renovated Egyptian galleries are expected to reopen in 2022.

Secondly, a century ago the sphinx spent a decade, from 1916 to 1926, in the main lobby and became a kind of unofficial museum mascot. Now, the hope is that visitors will welcome its return. The ancient sphinx, with the face that’s been eroded away by eons of blown desert sand, will become the “new” face of the museum.

“The sphinx is the unofficial mascot of the museum,” said Julian Siggers, museum director. “Everybody will be able to see him as they come in.”

The decision to return him to the lobby location is a change from plans that had been announced last summer, when the museum told the public the iconic artifact would be going on an extended “staycation” during the Lower Egyptian Gallery’s anticipated four- to six-year reconstruction. When the new lobby opens in November, the sphinx will have been out of view for just over 16 months.

When a visitor popped in on the sphinx last week in its old Lower Egyptian Gallery haunt, it sat on its pedestal of pine railroad ties, partially covered with a dusty plastic tarp, looking a bit forlorn and lonely. The gallery was littered with dismantled columns soon to move to the Upper Egyptian Gallery, and all was very quiet except for the humans talking amidst the slowly settling dust.

Before Wednesday’s big move, Thurlow said, the sphinx will be lifted off its railroad ties and lowered onto air dollies on the floor with the use of hydraulic gantries capable of hoisting 40,000 pounds. (The sphinx weighs a little more than 25,000 pounds.)

On the terrazzo floor, the sphinx will sit on four air dollies (each flattish dolly is about four by four feet). They will then almost literally float the sphinx 68 feet across the room, upheld by the power of a massive air compressor. When it reaches scaffolding rising about four feet to window level, the sphinx will stop and rest — something a sphinx does well.

It will then be hoisted by gantry onto the scaffolding and moved out the window onto the trestle-supported track running around an interior courtyard and into a main lobby window.

There will be inches to spare there – the sphinx is 48 inches wide and the window is 51 inches.

The move along 212 feet of track — on air dollies and machinery wheels pushed by a motorized pallet jack — includes two 45-degree turns and two stretches of inclined track measuring 91 feet.

”We’ve had four engineering firms looking at this,” Thurlow said. “The scaffolding itself can support 30,000-plus pounds, the soil in the courtyard can support that much weight.”

Once through the lobby window, the sphinx will travel 20 feet to its exhibition spot.

“We’re confident the weight won’t be a problem,” Thurlow said.

The planning is far more meticulous than when the sphinx first arrived in Philadelphia by steamer from Suez in 1913. No sooner did the German ship, the Schildturm, dock in South Philadelphia than it was pointed out there was no way to get the sphinx off the boat at that location. So the next day the ship headed upriver to the great Reading Railroad dock in Port Richmond.

Once there, it was lifted off the boat by a 100-ton heavy lift crane (used by the railroad for hoisting locomotives), put on a railroad flatbed car, and taken to the Reading yard at 23rd and Arch Streets.

From there it was eventually transferred by steam crane to a cart drawn by nine horses. They labored to pull the sphinx over the Market Street bridge to the entrance of the museum at 33rd and South Streets.

On Oct. 19, 1913, The Inquirer reported that the sphinx passed through the city “with an escort of 50 brawny workmen and a crowd of Penn students,” attracting “the attention of many hundred passers-by, as this was the first time [the sphinx] had been uncovered.”

Once at the museum, according to The Inquirer, the sphinx "was then lifted over the wall of the museum by a derrick and placed on a track of timbers that reached from the wall to the inside garden of the museum. A police guard was established to prevent souvenir seekers from chipping off pieces.”

It remained outside for three years, until concern about the impact of snow and cold weather led the museum to move it inside to the entrance lobby (using rolling logs for at least part of the move).

There it stayed for a decade — in a spot about 20 feet from where it will rest after Wednesday’s move. In 1926 the sphinx was moved to the Lower Egyptian Galleries through an unfinished back wall.

“It was then sealed in,” said Wegner. “We never thought it would be moved again.”

And how will the sphinx fare in its new location? What does it say about the museum?

“I think he stands for a lot of things this museum represents,” said Wegner. “Archaeology. Discovery. Mystery. Knowledge. Technology. All of these things can be connected to the sphinx.

“Plus, he tells a great story."