The Eastern Oblique Arc in Western Maine and New Hampshire

[Papa-Bear-NYC]

The Eastern Oblique Arc in western Maine and New Hampshire

 

Last weekend I finished up a section of the Eastern Oblique Arc, namely those stations between the Epping Base net and Massachusetts. What's that all about?

 

The Eastern Oblique Arc was an extended effort undertaken by the Coast and Geodetic Survey (and their earlier incarnation, the Coast Survey) in the 19th century for a high precision triangulation of the east coast of the US. This was used later to calculate the first precise measurement of the shape of the earth in North America. This section was finished in the 1840s and 1850s.

 

Holograph has a nice introduction to this on his site: Holograph's EOA Wiki

 

I have contributed a few threads over the last year of my efforts to track down the stations of this net and find whichever ones are still findable. Here's some links to my old threads:

 

Sept. 2007: My vacation intersects the Eastern Oblique Arc

April 2008: The Eastern Oblique Arc crosses Massachusetts

July 2008: The EasternOblique Arc meets the Borden Survey

 

This report finishes my searches for the section in Western Maine and New Hampshire (except for Mt. Washington - a separate undertaking) and leaves only the 6 stations of the Epping Base Net in Maine. I hope to work on these in September. Pray for good weather.

 

The following map shows the stations involved here. This is a screen shot of an interactive Google Map. I encourage you to click on the screen shot map which will bring up the real map. You can zoom and pan as usual, and for each station you can click on the icon and bring up a separate map for that station. The color code is Green = Found, Red = Not Found (possibly destroyed) and Grey = not yet visited,

 

 

The New Hampshire stations were covered in the last thread from July so I won'r repeat that information here. I'll give a brief account of the Maine stations in the following note, and after that I'll add a few tidbits on related topics.

 

A summary:

 

New Hampshire

Mt Washington - not reliably found since the 1950s (in spite of what gets logged on GC!), possibly lost.

Gunstock - original copper bolt found in good condition. Now an NGS Cooperative Base Network Control Station.

Monadnock - original drill hole and all original reference marks found in good condition. Now an NGS Cooperative Base Network Control Station.

Unkonoonuc - station lost, replaced by Unkonoonuc 2 in 1959.

 

Maine

Agamenticus - Reset with a disk in 1933. Disk recovered in good condition. See my report in This Thread from July 2008.

Independence - Destroyed in 1970. Replaced by Mt Independence (1974).

Pleasant - Original copper bolt recovered in good condition. "Sister Station" Mt. Pleasant New recovered in poor condition, only partial drill hole remains.

Mt. Blue - Reset by disk in 1928. Disk recovered in good condition.

Sebattus - Lost, possibly destroyed. Large structure built on top of site.

Harris - Reset by disk in 1932. Disk recovered in good condition.

Ragged - Original copper bolt recovered in good condition.

Humpback - will be searched for as part of the Epping Base net.

Mt.Desert - Reset with a disk in 1931. Disk found in good condition. See my report in This thread from Sept. 2007.

 

Note - many of these had been recovered by other GC members. Checking the reports here was (as always) very helpful.

Edited August 20, 2008 by Papa-Bear-NYC

[Papa-Bear-NYC]

Eastern Oblique Arc - stations in Western Maine

 

OC2305 AGAMENTICUS RESET - 1847 Copper Bolt replaced by a Disk in 1933

Visited in July with royswkr. We had read some the recent logs and studied the aerial photos and our main concern was that the station was under a viewing platform recently built over the foundation of the old WWII radar tower. We needn't have worried - when we measured how far the old concrete was from the side of the platform, we knew the station was at least 6 feet away from the platform. Then we noticed a large cracked field stone about 2 x 2 feet in size and about 4 inches thick just at the right spot. 20 minutes later, we had the stone off the spot and the debris underneath cleared and there was our disk pretty as can be at the bottom of a PVC pipe extending to about a foot underground. Some one saved us a h*ll of a lot of digging. We didn't look for the RMs.

Station OC2305 - Agamenticus reset - Interactive Google Map

 

 

 

PF1145 MT PLEASANT OLD - 1847?? Copper Bolt

PF1147 MT PLEASANT NEW - 1851?? Copper Bolt

This was a real curiosity. The original copper bolt was set in about 1847 (the NGS log says 1853) But almost immediately someone built a hotel blocking the view from the station so another station was set about 50 feet away. For about 100 years there was confusion as to which was the "real" station. By 1958 the hotel was long gone and the NGS just made two stations, the OLD and the NEW (even though by our standards both are about equally old). It is probable that when the EOA was surveyed, sometimes one and sometimes the other were used for observations. Probably they should have stuck with one station (the OLD) and called the other point an eccentric. Whatever! Read the NGS datasheets for these two and try to stay un-confused!

 

I visited this site twice - once in July with royswkr and again in August. In July we found the OLD station quite readily, but the NEW one took some digging. We finally found a drill hole (all the old reports said the bolt was falling out) but for something like this, one can never be 100% sure..

 

So I came back in August and spent a fair amount of time clearing brush to get clean tape lines, measuring everything and taking more detailed pictures of the old drill hole.

 

I came away satisfied that this this hole was in fact Mt Pleasant New. In fact I think it was one of the best results of the weekend. Most convincing were the tape measurements. After correcting for the slope of the tape, primarily going up and over the high point of the ridge and down again, the measurement between NEW and OLD was within an inch, and that between NEW and RM1 was within about 1.5 inches. The distance to RM2 was not so good (6 - 7 inches) but that was only a disk shank and may have been disturbed. The station-to-station distance was the most reliable since it was actually measured on the ground and that measurement is very close to one made by calculating an Inverse between the two geodetic positions (they are both first order stations).

 

When you click on this Google map you can see where the old and new stations are but you lose part of the aerial imagery. Sorry. You can zoom out one level and see the imagery although the stations then get a little scrunched together.

Station PF1147 - Mt Pleasant Old - Interactive Google Map

 

OLD copper bolt

 

NEW drill hole

 

OC1966 MT INDEPENDENCE - 1849 Unknown surface mark, replaced by Disk in 1912, destroyed in 1970

 

This station (not on GC) was destroyed in 1970. This was reported to the NGS by the Maine Dept. of Transportation. I tried to find out from colleagues at the NGS and the Maine DOT if any reports existed of the "destruction" (what happened and why), but none were found. The location is very near to a lookout tower built in the 1970s, which may explain the destruction, but the actual location of the station is outside the tower foot print (about 17.5 feet from its center). So I thought I would go there anyway and do some probing to see if any remnant of the mark was still there.

 

I arrived late on the day after a long drizzly drive from the Boston area (and an earlier long bus ride from NYC) and after finding the place and hiking about a quarter mile to get to the station, I unfortunately found that the location was inside a locked fence around the tower, so I had to just acknowledge that is gone.

 

A new mark was set in 1974 by Maine DOT OC1972 MT INDEPENDENCE. I recovered that, so at least I got something out of this drizzly visit.

 

Zoom in one level on the following map and you'll see the area and the location of the station and all ties.

Station OC1972 - Mt Independence (1849 - destroyed) - Interactive Google Map

 

Area behind fence wher the old station was located

 

PF1052 - SEBATTUS - 1853 Copper Bolt - under a new building

 

This was the major disappointment of the weekend. The hike up is an easy one - we found a logging road at the end of a street north of the peak. But when we were about half way up to the top, we found a much better road which evidently came in from the west (this got me suspicious). When we got to the top, we were very disappointed to find several new structures, one of which was a very ugly building sitting right on top of the station. It is really a shame to have lost this important historic marker.

 

But I logged the station "Not Found" rather than "Destroyed" since in principle the mark is still there and might some day be found if the building is ever torn down. I found both RMs. Since each one was pointing directly at the building from a different angle, there was no hope that the station escaped its fate.

 

Incidentally, the correct spelling of the name of the hill is "Sabattus", but the Coast Survey spelled it with an "e" so that's the way it is.

 

Note that the new building is not shown in this aerial view, indicating it was built in the last year or two.

Station PF1052 - Sebattus - Interactive Google Map

 

New ugly building on the hill top

 

Continued on next note ...

Edited August 21, 2008 by Papa-Bear-NYC

[Papa-Bear-NYC]

Eastern Oblique Arc - Western Maine stations

 

PF1037 MT BLUE - 1853 Iron Bolt in Drill Hole replaced by a Disk in 1928

This was a bit of a drive but the peak is a fairly popular destination. On good days (not today) there are great views. I climbed this peak a few years ago but neglected to find the mark which is "hidden". The hike took me a little over an hour. On the way up I saw a couple off to the side picking wild blue berries, which were in season.

 

The station was covered by a cairn (a pile of rocks) under the tower. The tower itself is (was) a station but the cabin disappeared from the steel legs years ago, so it's now destroyed as a station. I dismantled the cairn and found a bright gold colored USGS disk. The two RMs were nearby - RM1 just off in the brush to the east and RM2 on the leg of the tower. Apparently it was moved there by mistake when the tower was built. Technically this should be called MT BLUE RESET, but they left the original name after the disk replaced the bolt, so that's the way it is. When I had finished taking pictures, I piled the rocks back over the mark. They do tend to protect it from vandalism.

 

Station PF1037 - MT BLUE - Interactive Google Map

 

The mark revealed after dismantling the cairn

 

PE2242 MT HARRIS RESET - 1855 Stake with a Nail replaced by a Disk in 1929

This is located on the top of Mt. Harris near Dixmont and is reached via an old road (signed Firetower Rd) from Rte 7, about 10 miles south of I-95. The old wooden tower was removed a few years ago and the remains set to a museum in Pennsylvania where the tower was originally used in the 1940s. The station and RM1 and RM3 were recovered as described. No sign of RM2 was found. This was missing as of 1953 and not found as of 1958. The station was first established in 1855 and was one of the primary stations of the EOA. The Resets done in 1928 and 1929 leads one to suspect the accuracy of this mark. Read the old reports from the datasheet for 1928, 1929 and 1953.

 

Station PE2242 - MT HARRIS RESET - Interactive Google Map

 

 

PE2366 RAGGED MTN - 1854 Copper Bolt

This was a twofold success: the old original copper bolt was found and it didn't rain while I climbed this lovely peak.

 

The station dates from 1854 and was one of the primary stations of the EOA. The original copper bolt was found in good condition as well as all the assorted iron bars and eye bolts. I found RM1 without a problem but failed to find RM2 after a brief search. I parked in the "Snow Bowl" parking lot, climbed up the ski slope as described in the AMC Maine Mountain Guide and then took the short trail along the ridge to the peak. On the way up, near the top of the ski slope I met a woman picking wild blueberries. They looked plentiful and delicious.

 

Station PE2366 - RAGGED MTN - Interactive Google Map

 

Edited August 20, 2008 by Papa-Bear-NYC

[NGS Surveyor]

Super work as usual!!

 

GeorgeL

NGS

[Papa-Bear-NYC]

Latitude stations in Maine

 

Moved to This thread

Edited August 22, 2008 by Papa-Bear-NYC

[+Klemmer]

Great Report! Thanks.