SIY4.TXT Locate a Point on the Earth from a Land Description 27 Chapter 4 Locate a Point on the Earth from a Land Description In this chapter you will relocate stations on the Earth from the land description. The method is the same as you used in Chapter 1, except that now you are plotting your map at full scale. For this chapter you will need: a) Silva Ranger type 15 compass, available for $40 from CAVE Inc, « Fast Road, Ritner, KY 42639. 606/376-3137. b) Your previous survey data, c) Your previous survey location. You will not need: a) Tapemeasure, altho when you do, a 200 foot Keson fiberglass surveyor's tapemeasure is available for $28 from CAVE Inc, « Fast Road, Ritner, KY 42639. 606/376-3137. b) Clinometer, c) Calculator, d) Assistant. e) You don't even need this computer, except to make a printout so that these instructions can be doodled with a pencil. This step is a bit trickier to learn. You will have the bad tendency to cheat on yourself. You will change the compass sighting or your pace length a little bit so that you will come out right on your previous station. Try to pretend that you have never been there before. Return to the scene of Chapter 3. Find your beginning station. You should remember where it is. Could a naive surveyor find it? To find station 1, follow the instructions in your land description. TO 1, FROM 0, set the compass for the number of degrees which you have recorded for COMPASS. Sight off in that direction, just like you were taking a compass direction. Your station is somewhere along that line. The distance along that line is however far you have written in the land description under TAPE, or PACE if you prefer. Measure off that distance along the compass direction. SIY4.TXT Locate a Point on the Earth from a Land Description 28 You are now at station 1, within the error of the method. If you are exactly where station 1 was the last time, then you are either cheating or you are exceedingly lucky. And don't cheat by moving the station. Once you have set station 1, use the same method to set station 2. This is so easy that if you can do it twice, you can do it forever. I hope that you are not disappointed to find that there is no magic is surveying. Finish setting the stations which you have in your land description. Try not to cheat. You need to get a intuitive feel for error. The way to do this is to make lots of errors in a place where they can be caught and measured. Your closure error should be less than 2 paces (or feet) plus 5% of the RUN. Run is how far you have surveyed around the loop which you are closing. If you have an assistant who is into playing this sort of game, you can give each other land descriptions to follow. You could even have a treasure hunt with an appropriate buried treasure at station 19. You can survey the same way with the land description in a deed or whatever. You will need to locate on the real Earth a corner described in the deed. It need not be the beginning corner used by the previous surveyor, only an identifiable corner. If you can't identify any corners, see Chapter 11 for instructions to try to find lost corners. Plot out a map first so that you know what you are doing. Tabulate the land description into the standard format. Do this at home where you can think about it when you get confused. You can see that you could start at any corner and go in either direction. Use the map to keep track of what you are doing. If you have a map or plat, but not the land description, measure the directions and distances from the map. You may have to draw some more north-south lines to use with the black meridian lines inside of the compass dial. Don't draw on an original document, photocopy it. WARNING: some copiers make distorted copies. Check your copy against the original. Most of the survey error comes from the compass. A one degree error in the compass reading produces an error of 1.7% of the tape distance at the location of the station. You can get a good feel for this by setting two stations next to each other and taking compass directions to them from another station. It might be more convenient to do this on a piece of paper rather than in the city park. Just do it somewhere to prove it to yourself. Take some good advice from an analytical chemist. Know where you must be careful (compass) and where you may just as well be fast and sloppy (tape). If you are reading the direction to one degree, then it is irrelevant to read the tape to a hundredth of a foot. This is the basic method of surveying, the ability to work in the three languages of map, land description, and the real Earth. All the rest is just a refinement of this basic method. If you have questions or problems, contact me.