survey tech

Around the Detroit urban and suburban area, most of the markers you will find will be ones that are frequently used and therefore many will already be well marked. For more of a challenge, you may need to head out to the woods or the farm country.

Its not a surveying term, its a commonly used expession in sports, when a player fails to catch a ball, indicating that he missed it because he made a weak effort and did not reach out far enough to get it. My reference was to the fact that this is just one of many such bogus recovery notes by the Power Squadron.

Its there in the NGS list as E 41. Just another case of "alligator arms" by the Power Squadron. Try for G 14 (MY0789), there are no reports on that one since it was set in 1959, but it sounds likely to still be there, since its set in a large boulder. Use the county search feature at the NGS website, it looks like you have enough to keep you busy for quite awhile, about 150 in Hillsborough County. [This message was edited by survey tech on May 03, 2003 at 10:03 AM.]

If its halfway up a high ridge, its unlikely to be a geodetic marker. A tri-station or any related mark would be at or near the top of the ridge for maximum visibility. Alabama, is a public land state, so I would guess that its most likely to be a section corner or quarter corner. You may be able to verify this by plotting the location on the appropriate USGS topo map, and seeing if it appears to be on a section line, which are the fine red lines on the topo map, depending on how detailed the mapping is in that particular area.

This is almost certainly a cadstral marker, not a geodetic marker. Its very typical of those in Arizona. Remember, geodetic markers are nearly always set with a view toward extreme permanence and solidity, which would not be the case here, with this one sticking up so precariously.

Thats great Jeff, its one of the oldest USGS disks I have ever seen, and in fine condition, considering its probably been submerged by flooding at times down through the years. Its an encouraging sign, which may indicate there are other very old ones surviving in your part of Alabama, in undeveloped or long neglected areas that are off the beaten path such as this. I know its a great feeling to come across one like this, like finding a 1903 coin in your change from the grocery store.

Rusty is right in general, except for the fact that Polaris is actually moving toward the north celestial pole at the present time, not away from it. Precession will eventually take it far from north and then right back around again in its infinitely repeating cycle, but this apparent motion is so gradual that no one alive today will ever see it more than one degree from true astronomical north. Due to this chance of fortune for those of us on earth during this period of history, determining true north on a clear night is very easy, and this has been the primary means of doing so for surveyors and navigators in modern times. The second method, using shadows, is not likely to give good results unless time is corrected to local apparent noon, which is too complicated to bother with for such a method which will only give approximate results even if done properly. Despite the fact that magnetic declination can cause deviation from true north of over 20 degrees in some parts of the continental U.S., a compass is still probably the best daytime alternative to observation of Polaris in most cases. Its easy to correct from magnetic north to true north, since the declination difference is provided on all USGS quad maps.

See also the thread "unusual/odd benchmark designations", which is currently near the bottom of page 9.

Rich Judging from your pictures, I would agree with your conclusion that D 56 has been vandalized. You have positively identified the object setting, the bridge, and verified the exact spot on that object, using the directions and dimensions given in the description, so you have a conclusive result. The difference between yours and the one mentioned by K&S is that in your case the object setting remains intact, although it may have stability issues as you stated. Therefore, many and perhaps most surveyors would consider it damaged but not destroyed, and continue to use the spot, since it is positively identifiable. The NGS, however, which adheres to the strictest interpretation, would consider it destroyed due to the absence of the disk.

The tri-stations represent the highest order of precision obtainable through conventional ground based geodetic survey methods. Its true that expert use of GPS can now produce stations of equal or potentially superior quality, but the capacity to do this on a large scale comparable to the nationwide triangulation network is only now coming into existence, so the existing tri-station network, which can be envisioned as a spider web covering the nation, remains the best tool available for all users of geodetic control, many of whom do not have high precision GPS yet, due primarily to the great investment of money and training time required to make full use of GPS technology. Furthermore, the cost of establishing new stations, equal in precision and value to the existing tri-stations, is very high, and is not born by surveyors, who are in business to make money of course, but passed on to their clients as a part of the cost of completing the particular project, of which setting the new stations is a part. In addition, any markers reset by private surveyors are generally considered by them to be for their use only, since the results of their labor are proprietary in nature, and thus the data pertaining to such reset markers would not typically be available to the public, or even to other surveyors, except through special request, rendering the value of the reset marker very limited. For a reset marker to be of full value to the public, it must be reset by a public agency certified to do such work properly, or a private surveyor working under contract for a government agency, and it must meet the very rigorous requirements set forth for such work by NGS, in which case, again, the high cost of the procedure is not born by the surveyor, but by the taxpaying citizens of the area involved. So in short, every existing tri-station has great value and every one lost is a small tragedy, both historically and economically.

Mr. Doyle is widely considered to be the foremost expert on geodetic surveying. He has devoted his professional career to improving the quality and usefulness of our national control network, using state-of-the-art equipment and methods. He has lead the effort to refine the precision of the network through superior mathematical adjustments, vastly improving its value in the technological era we are now entering. The method of leveling he is describing here is known as differential leveling, which has been the conventional method prior to the dawn of GPS. It is still the most reliable and commonly used method, but the ongoing advancement of GPS technology will eventually replace it, probably at some time in the new century.

Corps of Engineers markers literally surround all of the large lakes they maintain, so finds of this type will probably be very common, especially during the summer months.

There are not too many markers under covers in sidewalks or other foot traffic areas, but its especially important to be careful with them. If the cover is damaged or not put back properly, a person stepping on it can easily break an ankle or a leg when it gives way.

If you cannot get permission to look at the markers, you can always get one of the city workers to read them for you, which would make it a perfectly legitimate find, in my opinion.

I agree, you did the right thing, nice work.

Nothing Very well put and spoken like a born surveyor. That is exactly the way most of us in the business feel about them. All the most memorable ones I have visited have been in the most remote places. After all, its about the journey.

Jeff Thats a very well written letter and it should serve the purpose just fine if the people are agreeable. I would stop by the tax assessors office and look up their names, which should only take a moment since you know the address, to make it more personal. A lot of people freak out about the government having any kind of interest in their land, even if they do not have an anti-government attitude to begin with, so I would de-emphasize the government references, and just concentrate on the historical value of the object, which is something nearly everyone can appreciate. In so doing however, be careful not to give them the idea that its something they can go out and dig up, like a buried treasure. Make sure they understand that its only valuable as long as it remains in place.

You cant go by the coordinates for ones like L 323, they are only approximate for true benchmarks like this one. Look for the several objects, such as fences, in the description. If you cant find any of the reference objects within a quarter mile or so up or down the road, then its likely that everything was wiped out when they built the mall. Unless you can find and positively identify at least one of the reference objects, its not possible to make a determination about the benchmark, because you cant be sure where it is or was. Many have survived construction and are just below the surface, but many others have been lost this way.

The oldest one I ever found was also from 1875, a stone marker in New Mexico. My oldest disks were one from 1906 in Virginia and one from 1908 in New Mexico. I have never heard of any disks older than 1900 being found, although there may be some out there, they were not used on a regular basis before about 1905.

Catcher It often happens that when points like these in urban areas are frequently used by all the local surveyors, no one sees any need to send in a recovery note, since everyone who needs to know about them already does. It not a bad idea though, since, as you say, so much time has passed.

Excellent work, 360, I guess it must have been in a pretty remote spot to have survived in its original condition so long, unless someone was protecting it. I would bet the men who set it never expected it to last half so long. I just hope that the people you notified about it will now follow through and take steps to insure that others will still be able to see it 110 years from now. Actually, you are in an ideal area, the desert southwest, for making these type of finds. The dryness of the climate out there is a major factor that allows points of this type to have even a chance to survive. Countless wooden posts were also set in the east and midwest, but any as old as yours would almost certainly have completely decayed by now in those areas.

Nice job, Greg, thats a description revision that was merited and will probably be genuinely helpful to others in the future. It would be a good idea for everyone to take this as a good example.

Yup, thats a goner, probably the victim of a demolition crew. The reason its considered destroyed rather just damaged or disturbed is because its been completely extirpated, so there is now no way of telling either its original location or elevation with any certainty. Its possible that a surveyor might be able to reset it with the use of his equipment and some supporting evidence, but this is difficult enough that it is seldom done, so its now most likely history.

Standards of accuracy are constantly changing due to technological advancement. What is considered accurate today may be considered sloppy in the future, just as the most accurate work of the past now looks less impressive by current standards. All NGS work is state-of-art at the time its done, but is subject to ongoing adjustments. The North American triangulation network is still considered the finest such network of its size ever created.

I agree with the others, but I would add that if you can verify the exact distances given to the crosses cut in the curb and also the distance to TU1445, assuming you found that one, then you can be sure that you have the correct spot. Unfortunately, markers like this one in high traffic areas obviously get a lot of attention and therefore often fall prey to vandals or collectors.