Has the Washington Monument shrunk? The only observable height change was the pyramid-shaped tip, which has been rounded off over time, possibly by frequent lightning strikes that melted the aluminum tip (Reuters)
Has the Washington Monument shrunk?
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Government surveyors have determined a height for the Washington Monument. It's nearly 10 inches shorter than what has been thought for more than 130 years.

The measurement puts the monument at 554 feet, 7 and eleven-thirty-seconds of an inch. That is measured from the floor of the main entrance to the top. Ever since the stone obelisk was completed in 1884, however, the historic height has been recorded at 555 feet, 5 and 1/8 inches. It's a number circulated for decades on tours of the capital and in civics classes.

The monument honors the nation's first president.

So could this be a case of an incredible shrinking monument? Has it sunk into the ground more than previously thought?

No, not even close, said the chief scientist at the National Geodetic Survey, which conducted the measurement with accuracy to within one millimeter.

Modern international standards from the Council of Tall Buildings and Urban Habitat an official guideline for building measurements call for a different base point than what was likely used in the 1880s, said Dru Smith, chief geodesist with the National Geodetic Survey. The standard measures from the lowest open-air pedestrian entrance to the building.

"The building didn't change height because of anything. It is just where you start from," Smith said.

The original measurement was conducted in 1884 by Lt. Col. Thomas Casey. He is believed to have used four brass markers as a base for measurement. Those markers remain in place. They are 9 inches below ground off each corner of the monument. It's possible the markers were at ground level in the past. A new plaza was installed around the monument more recently.

"It's clear that what was ground level has changed over the years," Smith said.

Measurements from the brass markers to the top in 1999 and 2014 essentially reconfirmed the original measurement. They showed the 1884 measurement was done with "incredible accuracy."

The only observable height change was the pyramid-shaped tip, which had been rounded off over time. Surveyors in 1934 also noticed the peak had been rounded. They believed it was due to frequent lightning strikes. The strikes had melted the aluminum tip.

"Well, this time around, we took very careful measurements," Smith said. "We were able to determine about 3/8 of an inch had been melted off from the very top."

That means the original 1884 measurement, completed with much less sophisticated equipment, was within 3/4 of an inch of the findings from the newest survey, using the original brass markers as a base point.

"It's remarkable, quite honestly, that they had the ability to get such an accurate measurement back in that time," Smith said.

The monument was completed in 1884. It was the world's tallest structure until 1889 when the Eiffel Tower was built. It remains by far the tallest structure in the nation's capital. The city strictly restricts building heights. Most buildings are shorter than the U.S. Capitol dome, which rises 288 feet.

The new survey was conducted while the monument was wrapped in scaffolding. The restoration work is being done because of a 2011 earthquake. Earlier survey results showed the monument did not sink further into the ground as a result of the 5.8-magnitude earthquake. The monument was built on land that used to be underwater. It has sunk about 2.2 inches since 1901.

The National Park Service is the caretaker of the monument. The service has no intention of changing its brochures or description of the height to reflect the new numbers.

"We'll still use the historic height rather than the architectural height, since they're measured from different places," said spokeswoman Jenny Anzelmo-Sarles.

The extensive survey will give the Park Service new data as a baseline. The service will track any changes in the monument's height, tilt or compression in the future.

"I think we can all agree the significance of the Washington Monument is really far greater than the architectural qualities or even its height," said Mike Commisso. He is a cultural resources specialist for the National Mall.

Critical thinking challenge: What changed to effect the official height of the monument?

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COMMENTS (70)
  • wyattg-Sch
    2/20/2015 - 10:57 a.m.

    The Main Idea is that the Washington monument is sinking. One important detail is that is was not made with as good as equipment it was today. One unimportant detail is that it was made in 1884. The mood is informational because they give lots of details.

  • jadej-Sch
    2/20/2015 - 11:05 a.m.

    7 and eleven-thirty-seconds of an inch in unimproved
    It's nearly 10 inches shorter than what has been thought for more than 130 years. imported
    MOOD worried
    they think the washingot monument is about to claps

  • shelbys-Sch
    2/20/2015 - 11:33 a.m.

    Fact:The monument honors the first nations president. The original measurement was taken in 1884. Opinion: They said the building didn't change height its where you measure it from. "I think we can all agree the significance of the Washington Monument is really far greater than the architectural qualities or even its height."

  • AmandaM-1
    2/20/2015 - 12:23 p.m.

    Government surveyors have noticed that the Washington Monument is ten inches shorter than it was one hundred thirty years. It is believed to be caused by frequent lightning strikes that melted the aluminum tip. Geographers have discovered that the real reason was the way that the monument was measured. The first measurement used brass markers on each corner. It was considered incredibly accurate. At the time those brass markers were at ground level. When the tower was measured again in 2014, the markers were nine inches underground. This explains the difference between the two measures. I don't really believe that the monument could shrink and it doesn't make perfect sense how the markers could go underground, but the story was still interesting.

  • CT14
    2/20/2015 - 01:07 p.m.

    It's weird to believe something so big isn't as big as you thought it originally was. To believe that something like this could shrink is difficult to imagine.

  • JH2001skater
    2/20/2015 - 01:12 p.m.

    it is shrinking because it is moving into the ground because of gravity and its pulling it down. This calls it to shrink in size.

  • Ze20010501
    2/20/2015 - 01:14 p.m.

    what changed the monument was they add to the monument every year so it can be bigger then they put Abraham their so it can look better

  • jaxsonbe-Sch
    2/20/2015 - 03:22 p.m.

    The main idea from this story it that surveyors say the Washington Monument has shrunk.
    Detail #1 It is now 3/8 of an inch in 1884 it was 3/4 of an inch.
    Unimportant detail #1 Surveyors in 1934 thought the tip was rounded.
    The mood in this story is confused and curious.

  • bioncawe-Sch
    2/20/2015 - 03:38 p.m.

    The main idea is telling us if or if not that the monument has shrunk. The detail #1 is how they measured it and its 554 feet and 7 and eleven thirty seconds of an inch. Detail #2 That they measure it every 130 years.

  • HudsonC-3
    2/20/2015 - 04:47 p.m.

    The washington monument has shrunk 10 inches from the last time recorded. That is a lot for a tall and narrow building. The original measurement was recorded in 1884. That is a long time ago. They should make it more stable and have a better foundation. Also make a wider base for it.

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