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DaveD

Washington Monument Survey

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Dave:

 

What do you know about the history of the mini obelisk? It appears that it's PID is HV1841 and it was first recovered by NGS in 1971. The monumented date is unknown by the Department of Defense. Does this go back to the original construction of the Washington Monument? If it is more recent it seems like it would have been a lot easier to just drive a rod rather than create a 12 foot tall buried version obelisk.

 

Enjoyed the podcast.

 

Tim Osborn

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The mini-Monument was the original bench mark established by Col. Casey of the Army Engineers who was the engineer in charge of the completion of the Monument. He set the mark to monitor settlement of the foundation during the construction. I know the datasheet says 1971 for the first time NGS visited the mark and I've tried for years to correct that. We actually first survey this mark in 1901 and on at least 13 different campaigns since then.

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The mini-Monument was the original bench mark established by Col. Casey of the Army Engineers who was the engineer in charge of the completion of the Monument. He set the mark to monitor settlement of the foundation during the construction. I know the datasheet says 1971 for the first time NGS visited the mark and I've tried for years to correct that. We actually first survey this mark in 1901 and on at least 13 different campaigns since then.

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The "key" you saw in the picture is a special tool we use to remove the threaded cap which covers the actual bench mark which is embedded in the side of the monument. Then we slide a 18" stainless steel pin into the cavity and place the level rod on the pin. Once the measurements are completed we remove the pin and replace the cap so the cavity doesn't get filled with dirt and other debris. Only NGS and the National Park Service have access to these special tools.

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The "key" you saw in the picture is a special tool we use to remove the threaded cap which covers the actual bench mark which is embedded in the side of the monument. Then we slide a 18" stainless steel pin into the cavity and place the level rod on the pin. Once the measurements are completed we remove the pin and replace the cap so the cavity doesn't get filled with dirt and other debris. Only NGS and the National Park Service have access to these special tools.

 

Oh. What is being measured?

 

Thanks.

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The "key" you saw in the picture is a special tool we use to remove the threaded cap which covers the actual bench mark which is embedded in the side of the monument. Then we slide a 18" stainless steel pin into the cavity and place the level rod on the pin. Once the measurements are completed we remove the pin and replace the cap so the cavity doesn't get filled with dirt and other debris. Only NGS and the National Park Service have access to these special tools.

 

Oh. What is being measured?

 

Thanks.

 

I'm going to make an educated guess that it was HV8077 in the photo, which would likely mean he was checking elevation.

http://www.ngs.noaa.gov/cgi-bin/ds_mark.prl?PidBox=HV8077

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