How accurate was Colvin’s work

Posted in Colvin points on November 10th, 2009
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I am often asked “how accurate were Colvin’s measurements”.

         Well, based on the extremely small sampling that I have personally re-measured, I would say it varies from better than what is typically obtained today to god awful. The better work appears to be that in which Colvin personally performed the observations and the worst appears to be that which was performed in his absence.

The following link, will take you to a web page entitled: “Kinematics and Dynamics of Strain Accumulation in the Adirondacks” USGS 1434-94-G-2473, Final Report by John Beavan, Lamont-Doherty Earth Observatory of Columbia University, Palisades, NY 10964

This 1995 report details the use of Colvin station marks in helping to determine the movement of the Adirondack Mountain range. A resulting un-intended conclusion of their work is found in the report  as follows: 

“Conclusion: The 1800’s triangulation surveys of the Adirondacks resulted in horizontal station coordinates precise to about 0.5 m (when selecting the best data available to us). The 1940’s survey resulted in precisions of 0.1-0.2 m. The 1995 GPS data gives precisions estimated at 0.01-0.02 m. The accuracies of the earlier surveys, while commendable for their time, are insufficient to detect deformation associated with the uplift of the Adirondacks.”

 Jim Vianna

 

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Colvin Reports Now Available

Posted in Colvin points on August 5th, 2009
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The N.Y.S. Library is in the process of scanning and electronically publishing all of Colvin’s reports to the N.Y.S. Legislators (and the maps found in those reports). A large portion of this work has now been completed and is available for downloading. The scans are in .pdf format and may take a considerable period of time to appear on your computer. I suggest the use of their FAQ page if you encounter problems. You will not be able to bookmark each report as they use a constantly changing URL. The best way to gain access to the downloads is by clicking below, then selecting the “search digital collections” bar located near the top of the page and then type in “Verplanck Colvin” in the search window

Colvin Reports

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Measuring Bars ???????

Posted in Colvin points on July 7th, 2009
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I first came across these pictures while visiting the Adirondack Research Center of the Association for the Protection of the Adirondacks about two years ago. Having never seen anything like this in the surveying world previously, to say it caught my interest is an understatement. Well, after keeping my ears open, I finally obtained the last Colvin report published for the years 1898-1899 which was edited by fellow crew member Norman J. VanValkenburg and published in 1989. Much to my surprise, therein was found a detailed report on the use of these measuring bars as written by Professor E. A. Fuertes, Director and Dean of the College of Civil Engineering of Cornell University. This report details the Professor’s work at Lake Placid in August of 1897.
                 While I admit that the following report is an exception rather than the norm for the expected accuracy of Colvin’s work, I find it extremely interesting and worthy of an easy future recovery.

  These two pictures show the crew measuring down the slope of land towards the shore of Lake Placid

 (Note: the use of two instruments in this process)

V4

                                     V5

 

Here is the actual report as told in Prof. Fuertes own words and as extracted from “REPORT OF THE SUPERINTENDENT OF THE STATE LAND SURVEY OF THE STATE OF NEW YORK FOR THE YEAR 1898″ edited by Norman J. Van Valkenburgh , The Adirondack Research Center of the Association for the Protection of the Adirondacks, 1989, first edition.

(Click on the individual page to open it in a larger window for ease of viewing)

scan0001

scan0002

  scan0003

scan0004

 scan0005

 Items worthy of note are: The Professor being upset with the monument being 1 mm out of position, 20 days to go 1,144 feet and a difference in the two runs of 0.002± of a foot.

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Is this a Colvin marker?

Posted in Colvin points on May 13th, 2009
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Many hikers are familiar with finding U.S.C.&G.S. (United States Coast and Geodetic Survey) disks on their favorite Adirondack peaks like this one:

usgs-1942

The question then becomes, does this marker occupy the original Colvin hole?  Well, based on V. Colvins report to the N.Y.S. Legislators, apparently the Federal Government was removing his markers and setting their own as far back as the late 1800’s:

colvin_journal_page_1

 

   Here is a picture of the crew at work on the same mountain top :

colvin_journal_page_2

 

So, It would appear that it probably was standard practice for the Federal Government to remove Colvin’s bolt and replace it with one of their own (mines better than your’s thing ). On rare occasions they left Colvin’s marker in place (See Ruby Mtn. write up). Both Colvin and the U.S.C.&G.S. points were and still are subject to vandalizism, resulting sometimes in only a drill hole being found today. Many times it is not possible to ascertain the truth but occasionally with additional research a likelyhood can be established as to the question of does this disk occupy Colvin’s point.

Jim Vianna

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Foot Holes???

Posted in Colvin points on May 5th, 2009
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Many people ask me if Colvin or his crew occupied every mountain to perform their work. Well it depends on what you mean by occupy. Yes, every mountain located had to have at least a bolt and signal placed upon it, but not every mountain was occupied by theodolite. One way you can determine this in the field is to look for small drill holes set out in a roughly equilateral triangle around the station mark. The triangles formed by these drill holes will have bases of three – four feet and be about three feet distant from the station mark. The purpose of these drill holes was to allow for the instrument tripod feet to have a place to rest in so they would not kick out if hit or blown about in heavy wind.

Here is a picture of one: rare-tripod-foot-drill-hole

 Here is a recent picture from the top of West Mtn. and our Raquette Lake recovery showing the station mark in the middle with the three foot holes in a triangle marked with white powder.

west-mtn-footholes

 As Colvin wrote in his 1874 report:

 

1874-excerpt

And that’s the tip of the day.

Jim Vianna

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