Share:
Notifications
Clear all

Geodetic Base Line Sign Dedication

Page 1 / 9

J. Penry
Posts: 1436
Member
Topic starter
(@j-penry)
1,000+ posts
Joined: 11 years ago

I gave a slideshow presentation yesterday describing the importance of the Page Base Line in northern Nebraska during the dedication of the historical sign. In 2007, a group of surveyors recovered both ends of the baseline. After the field was plowed up at the NE Base end, the surface monument was put on display in town. We finally got a sign dedicated to explain the monument and the baseline. Be sure and click on "Full Story" on the website link if you want to know the full details.

Website:
http://www.penryfamily.com/surveying/pagebaseline.html

42 Replies
Bill93
Posts: 8098
Member
(@bill93)
5,000+ posts
Joined: 11 years ago

Great work. It's always good to remind the public that surveying is important.

Did anyone consider an EDM traverse to compare to the original distance measurement?

Reply
EFBURKHOLDER
Posts: 124
Member
(@efburkholder)
100+ posts
Joined: 10 years ago

Mr. Penry,

That is a fascinating post - lots of historical significance. I read the associated article and have questions - I'll contact you through your web site for follow-up.

FYI, I was licensed as a surveyor in Nebraska nearly 40 years ago. Wonderful state.

Reply

J. Penry
Posts: 1436
Member
Topic starter
(@j-penry)
1,000+ posts
Joined: 11 years ago

It is my personal belief that there are no instruments available to the general surveying community today that could remeasure the geodetic baselines established by USC&GS more than a century ago. The reason is that they were measuring these baselines in microns with instruments such as the Ice Bar or Duplex Bars that required the use of microscopes to record the readings. They were also keenly taking into consideration atmospheric conditions upon every single measurement. The Duplex Bars were under a tent that was pulled by horses. Fifteen different men assisted in making each 5-meter measurement. Three separate thermometers were placed at each reading. Any measurement made today with an EDM or with GPS would only be a distance comparable to one made with a like instrument and not directly comparable to the length as established by USC&GS.

But, to answer your question, the lengths have not been remeasured and it would be an interesting experiment to see how far "off" a modern measurement would be compared to the exact measurement made by USC&GS.

Reply
J. Penry
Posts: 1436
Member
Topic starter
(@j-penry)
1,000+ posts
Joined: 11 years ago

Page Base Line - Then/Now

The Page Base Line was measured to be 8251.7569 meters in 1900. NGS has current NAD 83(1995) positions of:

NE Base
N 42°28'53.47527"
W 098°22'13.99939"

SW Base
N 42°25'25.39941"
W 098°26'00.79833"

The current values are adjusted from the original positions.

Does the distance between these two positions equal 8251.7569 meters when describing the length of this base line? Comments?

Reply
Page 1 / 9
Share: