Plot a Map from a Land Description
SIY1.TXT Plot a Map from a Land Description 72
Chapter 1
Plot a Map from a Land Description
For this chapter you will need:
a) Silva Ranger type 15 compass, available for $40 from CAVE Inc, 1/2 Fast
Road, Ritner, KY 42639. 606/376-3137. If you do not have this item, then you
cannot execute these instructions. Instead, you must use the instructions in
Chapter 1_C, "Plot a Map the Cheapie Way".
b) These instructions,
c) Pencil & notepaper,
d) Calculator. A common calculator makes the arithmetic a lot easier. If you
don't own a calculator, I suggest that you purchase one. The cost is between
$2 and $10, available almost everywhere. The most significant difference
amongst calculators is the quality of the keypad. Everybody skip the fancy
math the first time. I find a hand calculator to be a lot more useful than a
popup "calculator" on a computer. I personally use a Sharp EL-510S (solar) and
a Sharp EL-506A (battery).
You will not need:
a) Any land,
b) Any land description,
c) Any assistant,
d) Nor to leave the comfort & safety of your kitchen.
e) Your computer, other than to print a printout of this chapter.
Forewarned thrice!!! Don't let the instructions which come with the compass
scare you off. If you do read their Instruction Manual, then tell me what you
think of it.
All that you really need to know is that the red end of the compass needle
points North. Because so many people kept forgetting this fact, the New and
Improved Silva Ranger Compass Type 15CL has the north end of the north arrow on
the compass painted red. Send your adulations to Silva Compass, Binghamton, NY
13902-1604. They even have a Customer Service Office at 800/572-8822.
SIY1.TXT Plot a Map from a Land Description 73
Open the compass. There is a graduated dial. Note that there is a mark every
2 degrees, with every 20 degrees labeled. Grab the dial and twist it around.
There is an index pointer line on the compass base under the mirror. It points
to the compass reading on the compass dial. The New and Improved Silva Ranger
Compass has done away with the index line, and has only an index blob.
Read the compass reading. Read it to 1 degree accuracy. Use a magnifying
glass if necessary. What is the compass reading? Write the compass reading
down on a piece of paper.
Is this the correct compass reading? I can't tell from here. You gotta check
your own work, starting right now. Read the compass reading again. Compare it
with what you have written down on your paper. Turn the compass dial and read
it again.
You can also set the compass reading on the compass dial to any reading. Set
the compass reading on the compass dial to 40 degrees.
If there are four 40s on your compass, this is because you have a compass which
is graduated in quadrants. You thought that you knew better than I, and had me
special order you a quadrant compass against my advice. The methods for
converting between the two systems of measurement are covered later in these
instructions. See page 78.
There are two distance scales along the sides of the compass base. One is
graduated in twentieths of an inch, the other in millimeters. There are two
more scales on the new Ranger, marked 1:25000 and 1:50000, which can be used to
measure distance on metric topo maps.
There is a compass needle which points North. You need to know that the red
end of the compass needle points North.
There is a device to internally adjust for magnetic declination. The
declination adjustor is the brass screw on the dial at 45 degrees.
Turn the declination adjustor with the screw driver on the lanyard. The
declination is read on the black declination scale under the tail of the black
arrow. Set the declination to 0 for now. If you have an old Ranger, then the
declination is set under the north end, the screwdriver is located on the
safety cord, and the scale is red. It makes no difference, but it might be
confusing to set the north declination on the south end of the compass if you
don't know what you are doing.
A survey station consists of some point with an individual name and location.
The survey station may be located on the land, in a land description, or on a
map.
SIY1.TXT Plot a Map from a Land Description 74
Survey stations on the land or on a map are connected together with lines,
similarly to a "Connect-the-Dots" puzzle. These survey stations might or might
not be corners of the property. Survey stations in a land description are
connected by a set of instructions telling you how to find the next station.
TABLE 1
Line Station Station COMPASS TAPE Comments
TO FROM degrees hundredths
of inches
1 0 0 0 0 You gotta start somewhere!
2 1 0 40 200
3 2 1 122 170
4 3 2 193 224
5 4 3 305 271 This is supposed to be the same
as station 0
Look at Table 1, Line 1. The station is named "0". This is the station TO
which you are surveying. The station FROM which you are surveying is also
named "0". The station refers to itself.
The COMPASS direction to TO from FROM is 0. The TAPE distance is also 0.
Each station must refer to either some previous station or be given some
arbitrary location. Be sure that you start someplace. The best directions in
the world are worthless if you don't know where to start. Have you ever asked
for directions in Rural America? If so, you are familiar with directions which
start at no where. Convert to now here.
Line 2 of Table 1. The station TO is named "1". The station FROM is named
"0". The COMPASS direction is 40. Set the dial on your compass so that the
compass reading is 40. Isn't this easy?
The TAPE distance is 200. In this case 200 hundredths of an inch. Now get out
Graph 1. This is 10 to the inch graph paper.
When you get around to using CAVEMAP1.BAS you will find Graph 1 there. Or you
could register this disk and I'll send you the graphs. Meanwhile, any piece of
lined paper can be used. Draw an arrow along one of the lines and write an "N"
near it. My graph has cheater lines on it, but they are not necessary.
SIY1.TXT Plot a Map from a Land Description 75
Turn the graph paper so that the North Arrow points up. Away. To the top.
Unless there is some very good reason not to do so, always put North at the top
of your map. This cartographic standard makes it much easier to keep the map
orientation fresh in your feeble little mind. You will learn to *!HATE!* maps
with North in any other direction.
Put the compass on the graph paper. Now turn the compass so that the red and
black orienting arrow points the same way as the North Arrow on your map. Your
compass is now oriented with the map. If you need to be more exact, use the
black meridian lines inside of the compass dial. Align these black lines with
the north-south lines on the graph paper. The compass needle is pointing
towards Magnetic North on Earth. If you have an old style Ranger, then these
lines are red and the arrow is all black. Same difference.
Now orient the map with the Earth. Turn the whole graph paper, leaving the
compass on the paper. Turn the paper until the red and black arrow inside of
the compass dial lines up with the compass needle. The New and Improved
Upgraded Foolproof Silva Ranger Compass Type 15CL has a red head on the arrow
so that you can remember which end is north. Those with the old fashioned
Ranger must remember "The arrow head and the needle red."
For now you can ignore the orientation of the map. Don't let the compass
needle confuse you.
Turn the graph paper so that the North Arrow points to the top. Put the
compass on the graph paper and turn the compass so that the red and black arrow
points the same way as the North Arrow on the map. Slide (don't twist) the
compass until the ruler edge of the compass goes thru where I have labeled an
"x" with the name "0". Now line up the black lines inside of the dial with the
north-south lines on the map. Be sure that the ruler edge of the compass still
goes thru the x. Now draw a line along the ruler edge, starting at the x and
extending towards the mirror. This is the plot of the compass direction. The
COMPASS direction is 40 degrees.
The TAPE reading is 200. That is 200 hundredths of a inch. The inches ruler
on the side of the Silva Ranger has a mark every 5 hundredths, a longer mark
every 10 hundredths, and is labeled every 50 hundredths. This is NOT a
sixteenths ruler.
Use the ruler to measure off 200 hundredths of an inch along the line
representing the 40 degree compass direction on your map. That's exactly 2
full inches. Start at the "x" which is labeled "0". You will find it more
accurate (and also more confusing!) to start measuring at the 1 mark on your
ruler.
Make an "x" 200 hundredths out the 40 degree direction line from station 0.
Label this station "1". Congratulations! You have just plotted your first
station. Wasn't that easy?
SIY1.TXT Plot a Map from a Land Description 76
If you can do it once, you can do it twice. On to line 3. The TO station is
2. The FROM station is 1. The way to get to TO from FROM is to go in a
COMPASS direction of 122 degrees from North, a TAPE distance of 170. Set the
compass reading to the compass direction of 122 degrees.
Put the compass on the map, orient the compass to North, ignore the compass
needle, and slide the compass until the edge passes thru the "x" labeled "1".
Align the black lines with the north- south lines. Draw the 122 degree
direction line on the map.
Now it gets tougher. The TAPE distance is 170 hundredths of an inch, measured
along the direction line. Remember, the ruler is more accurate if you don't
start at the cut corner. Put an "x" 170 hundredths out the 122 degree
direction line from station l. Label this station "2".
You can locate the station more accurately if you first mark the spot with a
tic, a little short line out from the proper spot on the ruler. A sharp pencil
helps too. Wasn't that easy?
If you can do it twice, you can do it thrice. Line 4 gives the instructions on
how to locate station 3. Plot the location of station 3 on your map. Mark it
with an "x" and label it "3". Hopefully that was easy. If you can do it
thrice you can do it a hundred times, or however long it takes to get the job
done.
Plot Line 5. Station 4 should be at the same place as station 0. Or at least
too close to call them different. If there is more that 20 hundredths of a
inch between them, try again.
If you have already tried again, give it up for a few days. You have
blundered, and it should be obvious in hindsight.
If it is already a few days later and you are still making the same mistake,
perhaps it is hopeless. You can send me back my instruments and instructions,
and I'll send you your dollars back. Be sure to enclose the maps which you
have tried to draw so that I can improve my instructions. Or just send me
copies of your maps and whatever else you have done, and I'll straighten you
out. If you have an idea of what went wrong, make a note of it. See the end
of this chapter for my address and phone number.
Everybody else now knows how to plot a map.
SIY1.TXT Plot a Map from a Land Description 77
The CLOSURE ERROR is the distance on the map between two stations which are
supposed to be in the same place. It is a check on the precision, and by
implication, the accuracy of your work.
Precision is like target shooting and getting all the bullets into the same
hole. You have either a good gun rest or a very steady hand. Accuracy is
getting them distributed around the bullseye on the proper target. Your rifle
is properly sighted in.
The closure error is best thought of as a percentage of the run. The RUN is
the distance which you have surveyed around a loop until you used the same
station again for the closing station. Just add up all the tape distances.
The run for the map of the land description in Table 1 is 865.
Measure the distance between station 0 and station 4 on your map. Divide this
by 865 and push the % key. If you have no distance between the stations, you
have 0% closure error. Congratulations.
TABLE 2
Line Station Station COMPASS TAPE Comments
TO FROM quadrants poles
1 10 10 0 0 Stone in Speed's line
2 11 10 S72E 293 3/4 Two white oaks
3 12 11 N37E 123 Corner with Davis & Green
4 13 12 N87W 352 Dogwood in Green's line
5 14 13 S3W 23 The beginning corner
Now look at Table 2. This is the land description of a real parcel of land in
Kentucky. The compass is recorded in quadrants and the distance is in poles.
This is the common land description notation in Kentucky.
You must translate the quadrant notation into the familiar 360 degree
notation. The meaning of the quadrant notation is to face the first direction
(North or South). Then turn the given number of degrees towards the second
direction (East or West). Line 2 has a compass reading of S72E. Set the
compass dial so that the pointer points to S, then turn it towards E for 72
degrees. The reading on your compass dial should be 108.
Now that you know what you are trying to do, you can take a mathematical
shortcut. You can subtract 72 from 180 and get 108.
SIY1.TXT Plot a Map from a Land Description 78
Where did the 180 come from, you ask? Look at your compass. S is 180. N is
360 or 0, whichever is more convenient. E is 90. W is 270.
To translate quadrants, use the following rules.
If the compass direction is a cardinal direction (N, E, S, or W) translate to
([0 or 360], 90, 180, or 270).
If a direction is within a quadrant, do the following with the number of
degrees in the quadrant:
If the quadrant is NE, then add the degrees to 0.
If the quadrant is SE, then subtract the degrees from 180.
If the quadrant is SW, then add the degrees to 180.
If the quadrant is NW, then subtract the degrees from 360.
To translate your normal compass direction (azimuth) into the quadrant system,
use the following rules:
If the direction is a cardinal direction ([360 or 0], 90, 180, or 270), then
translate into (N, E, S, or W).
If the compass direction is greater than 0 and less than 90, then the degrees
are correct and the quadrant is NE.
If the compass direction is greater than 90 and less than 180, then subtract
the degrees from 180, and the quadrant is SE.
If the compass direction is greater than 180 and less than 270, then subtract
180 from the degrees, and the quadrant is SW.
If the compass direction is greater than 270 and less than 360, then subtract
the degrees from 360, and the quadrant is NW.
Play with the compass dial whenever you are in doubt.
Believe it or not, this system made a lot of sense in Antiquity, when the
arithmetic was done by hand. Today it is an anachronism. It's only use in the
present world is to confuse those who would survey it themselves.
A pole is the same as a rod. 16.5 feet. This one made sense in the days
before the invention of the tape measure. But for now, plot at a scale of 100
poles to the inch.
Typical Kentucky land corners are identified under the Comments.
SIY1.TXT Plot a Map from a Land Description 79
Translate the compass readings and plot a map of this survey. You can plot it
on the same graph paper as you used before.
When I plotted a map of the data of Table 2, I really couldn't see any closure
error. Calculating with a hand calculator, I determined the closure error to
be 3.0 poles, or 0.4%. The direction to station 0 from station 4 is 293
degrees. Compare this with the closure error of your plot. Remember, the
percent closure error is the map measured distance between the two stations
representing the same location on the ground, divided by the run around the
surveyed loop, times 100%. You should come out with a closure error of less
than 2%. Anything more is blunder.
A bit more about blunder and error. Error is a small difference of opinion
which sneaks into your measurements. This is due to the unfortunate fact that
the real world isn't mathematically perfect.
Error is part of this method. So far, you have made errors in setting the
declination adjustment, in setting the degrees on your compass dial, in
aligning the compass with north on your map, in placing the compass edge so
that it goes exactly thru the previous station, in setting the beginning end of
the ruler exactly on the station, in guesstimating exactly where some reading
such as 293 3/4 is on the ruler, and finally in getting your pencil in exactly
the right spot. And then there are manufacturing errors in the compass. Plus
a few more I didn't think of.
You can never eliminate all the errors. Just realize that they are there, and
manage them.
Blunders are the *BIG* mistakes. The most common blunder in surveying is to
read the wrong end of the compass. You are going just exactly bassackwards
from where you think you are going. Blunders are obvious when you notice
them. When eliminated, they are gone completely. Except when someone reminds
you of the time when you surveyed for half a day before realizing that your
compass was always pointing toward your new beltaxe!
Blunders, by definition, are big enuf to catch and cure. Always be sure that
your work has built-in blundertraps. When they are not caught, little blunders
become BIG ERRORS.
SIY1.TXT Plot a Map from a Land Description 80
Table 3
TO FROM COMPASS TAPE COMMENTS
20 20 0 0
21 20 122 127 feet
22 21 8 169 feet
23 22 3 103 feet
24 23 86 211 feet
25 24 92 174 feet
26 25 S15E 12 poles
27 26 S14E 5 rods 7 links
28 27 S86W 7 poles 5 links
29 28 S2E 1 chain 32 links
30 29 S86W 13 rods 13 links
31 30 N4W 6 poles 1.5 links
32 31 N8E 3 rods
33 32 278 245 feet closes on 20?
34 33 237 15 feet closes on 20
Table 3 gives you some more practice in plotting a map. Note that the
direction and distance units vary. Translate of all this into degrees and
feet. Plot a map from this land description.
What sort of closure error did you get? What is this in terms of percent
closure error? Is this an acceptable closure error? The actual calculated
closure error is 0.00%. Station 33 was supposed to be the closing station as I
produced these data. The distance for station 34 is my closure error when hand
plotting the map. My hand plotting error was 0.8%, which I consider to be
excessive. That's why I use a computer. And the computer is easier too.
SIY1.TXT Plot a Map from a Land Description 81
Take another look at your map. The closure error should be quite small. Now
look at the boundary of the parcel and think about it. Is it possible to make
a blunder and still have a small closure error? Possible, but not probable.
You are now ready to plot a map of whatever interests you. You may need to
translate the land description into the proper format to plot. Some units of
distance which you may encounter are: a pole or a perch or a rod, 16.5 feet; a
rope, 20 feet; a chain, 66 feet; a link, [a hundredth chain] 0.66 feet; a
furlong, (ten chains) 660 feet; a yard, 3.00 feet; a meter, 3.28 feet; la vara,
2.78 feet (Texas. variable).
If your map comes out too tiny, or if it won't fit on the paper, then you will
have to change the scale of your map. A square plot containing 10 acres has
the length of each side exactly one furlong, or 660 feet. At a scale of 100
feet per inch, the map of that 10 acre square would be 6.6 inches square. This
fits nicely on the graph paper. You might want to plot on a few different
scales just to see what happens. If you run off the graph paper, you can add
another piece to that side. Line up the gridlines. Mark how the two sheets
connect, or tape them together.
You can obtain a copy of a deed for a parcel of land by visiting your Recorder
of Deeds, or whatever title he holds in your county. Just walk into the
courthouse and ask for the deeds.
You will need help finding what you want, so ask. The deeds are indexed in
various ways, depending upon where you are. In Wayne County Kentucky, deeds
are indexed alphabetically by date. Really. I told you that you would need
help!
I find the three little rubber map grippers on the compass to be an annoyance.
They are meant to keep the compass from slipping on the map paper. They work
too well. Just pull them out and stick them onto the compass box with a piece
of sticky tape. You might want them again when using the compass with a topo
map in the field.
If your deed does not give directions and distances, you are out of luck.
There is no way to determine where a boundary given simply as "bounded by John
Dough's property on the south" is, unless it is stated on John Dough's deed.
You will just have to skip drawing a map from the deed.
You may prefer to use a separate circular protractor and ruler for plotting.
But start with the Silva Ranger. Using the Silva for plotting on paper will
teach you how to use it for surveying.
For those of you with land in Township & Range territory, see Chapter 6.
If you have any questions, problems, or comments, write or call me.
Dave Beiter, CAVE Inc, 1/2 Fast Road, Ritner KY 42639. 606/376-3137.
Chapter 1
Plot a Map from a Land Description
For this chapter you will need:
a) Silva Ranger type 15 compass, available for $40 from CAVE Inc, 1/2 Fast
Road, Ritner, KY 42639. 606/376-3137. If you do not have this item, then you
cannot execute these instructions. Instead, you must use the instructions in
Chapter 1_C, "Plot a Map the Cheapie Way".
b) These instructions,
c) Pencil & notepaper,
d) Calculator. A common calculator makes the arithmetic a lot easier. If you
don't own a calculator, I suggest that you purchase one. The cost is between
$2 and $10, available almost everywhere. The most significant difference
amongst calculators is the quality of the keypad. Everybody skip the fancy
math the first time. I find a hand calculator to be a lot more useful than a
popup "calculator" on a computer. I personally use a Sharp EL-510S (solar) and
a Sharp EL-506A (battery).
You will not need:
a) Any land,
b) Any land description,
c) Any assistant,
d) Nor to leave the comfort & safety of your kitchen.
e) Your computer, other than to print a printout of this chapter.
Forewarned thrice!!! Don't let the instructions which come with the compass
scare you off. If you do read their Instruction Manual, then tell me what you
think of it.
All that you really need to know is that the red end of the compass needle
points North. Because so many people kept forgetting this fact, the New and
Improved Silva Ranger Compass Type 15CL has the north end of the north arrow on
the compass painted red. Send your adulations to Silva Compass, Binghamton, NY
13902-1604. They even have a Customer Service Office at 800/572-8822.
SIY1.TXT Plot a Map from a Land Description 73
Open the compass. There is a graduated dial. Note that there is a mark every
2 degrees, with every 20 degrees labeled. Grab the dial and twist it around.
There is an index pointer line on the compass base under the mirror. It points
to the compass reading on the compass dial. The New and Improved Silva Ranger
Compass has done away with the index line, and has only an index blob.
Read the compass reading. Read it to 1 degree accuracy. Use a magnifying
glass if necessary. What is the compass reading? Write the compass reading
down on a piece of paper.
Is this the correct compass reading? I can't tell from here. You gotta check
your own work, starting right now. Read the compass reading again. Compare it
with what you have written down on your paper. Turn the compass dial and read
it again.
You can also set the compass reading on the compass dial to any reading. Set
the compass reading on the compass dial to 40 degrees.
If there are four 40s on your compass, this is because you have a compass which
is graduated in quadrants. You thought that you knew better than I, and had me
special order you a quadrant compass against my advice. The methods for
converting between the two systems of measurement are covered later in these
instructions. See page 78.
There are two distance scales along the sides of the compass base. One is
graduated in twentieths of an inch, the other in millimeters. There are two
more scales on the new Ranger, marked 1:25000 and 1:50000, which can be used to
measure distance on metric topo maps.
There is a compass needle which points North. You need to know that the red
end of the compass needle points North.
There is a device to internally adjust for magnetic declination. The
declination adjustor is the brass screw on the dial at 45 degrees.
Turn the declination adjustor with the screw driver on the lanyard. The
declination is read on the black declination scale under the tail of the black
arrow. Set the declination to 0 for now. If you have an old Ranger, then the
declination is set under the north end, the screwdriver is located on the
safety cord, and the scale is red. It makes no difference, but it might be
confusing to set the north declination on the south end of the compass if you
don't know what you are doing.
A survey station consists of some point with an individual name and location.
The survey station may be located on the land, in a land description, or on a
map.
SIY1.TXT Plot a Map from a Land Description 74
Survey stations on the land or on a map are connected together with lines,
similarly to a "Connect-the-Dots" puzzle. These survey stations might or might
not be corners of the property. Survey stations in a land description are
connected by a set of instructions telling you how to find the next station.
TABLE 1
Line Station Station COMPASS TAPE Comments
TO FROM degrees hundredths
of inches
1 0 0 0 0 You gotta start somewhere!
2 1 0 40 200
3 2 1 122 170
4 3 2 193 224
5 4 3 305 271 This is supposed to be the same
as station 0
Look at Table 1, Line 1. The station is named "0". This is the station TO
which you are surveying. The station FROM which you are surveying is also
named "0". The station refers to itself.
The COMPASS direction to TO from FROM is 0. The TAPE distance is also 0.
Each station must refer to either some previous station or be given some
arbitrary location. Be sure that you start someplace. The best directions in
the world are worthless if you don't know where to start. Have you ever asked
for directions in Rural America? If so, you are familiar with directions which
start at no where. Convert to now here.
Line 2 of Table 1. The station TO is named "1". The station FROM is named
"0". The COMPASS direction is 40. Set the dial on your compass so that the
compass reading is 40. Isn't this easy?
The TAPE distance is 200. In this case 200 hundredths of an inch. Now get out
Graph 1. This is 10 to the inch graph paper.
When you get around to using CAVEMAP1.BAS you will find Graph 1 there. Or you
could register this disk and I'll send you the graphs. Meanwhile, any piece of
lined paper can be used. Draw an arrow along one of the lines and write an "N"
near it. My graph has cheater lines on it, but they are not necessary.
SIY1.TXT Plot a Map from a Land Description 75
Turn the graph paper so that the North Arrow points up. Away. To the top.
Unless there is some very good reason not to do so, always put North at the top
of your map. This cartographic standard makes it much easier to keep the map
orientation fresh in your feeble little mind. You will learn to *!HATE!* maps
with North in any other direction.
Put the compass on the graph paper. Now turn the compass so that the red and
black orienting arrow points the same way as the North Arrow on your map. Your
compass is now oriented with the map. If you need to be more exact, use the
black meridian lines inside of the compass dial. Align these black lines with
the north-south lines on the graph paper. The compass needle is pointing
towards Magnetic North on Earth. If you have an old style Ranger, then these
lines are red and the arrow is all black. Same difference.
Now orient the map with the Earth. Turn the whole graph paper, leaving the
compass on the paper. Turn the paper until the red and black arrow inside of
the compass dial lines up with the compass needle. The New and Improved
Upgraded Foolproof Silva Ranger Compass Type 15CL has a red head on the arrow
so that you can remember which end is north. Those with the old fashioned
Ranger must remember "The arrow head and the needle red."
For now you can ignore the orientation of the map. Don't let the compass
needle confuse you.
Turn the graph paper so that the North Arrow points to the top. Put the
compass on the graph paper and turn the compass so that the red and black arrow
points the same way as the North Arrow on the map. Slide (don't twist) the
compass until the ruler edge of the compass goes thru where I have labeled an
"x" with the name "0". Now line up the black lines inside of the dial with the
north-south lines on the map. Be sure that the ruler edge of the compass still
goes thru the x. Now draw a line along the ruler edge, starting at the x and
extending towards the mirror. This is the plot of the compass direction. The
COMPASS direction is 40 degrees.
The TAPE reading is 200. That is 200 hundredths of a inch. The inches ruler
on the side of the Silva Ranger has a mark every 5 hundredths, a longer mark
every 10 hundredths, and is labeled every 50 hundredths. This is NOT a
sixteenths ruler.
Use the ruler to measure off 200 hundredths of an inch along the line
representing the 40 degree compass direction on your map. That's exactly 2
full inches. Start at the "x" which is labeled "0". You will find it more
accurate (and also more confusing!) to start measuring at the 1 mark on your
ruler.
Make an "x" 200 hundredths out the 40 degree direction line from station 0.
Label this station "1". Congratulations! You have just plotted your first
station. Wasn't that easy?
SIY1.TXT Plot a Map from a Land Description 76
If you can do it once, you can do it twice. On to line 3. The TO station is
2. The FROM station is 1. The way to get to TO from FROM is to go in a
COMPASS direction of 122 degrees from North, a TAPE distance of 170. Set the
compass reading to the compass direction of 122 degrees.
Put the compass on the map, orient the compass to North, ignore the compass
needle, and slide the compass until the edge passes thru the "x" labeled "1".
Align the black lines with the north- south lines. Draw the 122 degree
direction line on the map.
Now it gets tougher. The TAPE distance is 170 hundredths of an inch, measured
along the direction line. Remember, the ruler is more accurate if you don't
start at the cut corner. Put an "x" 170 hundredths out the 122 degree
direction line from station l. Label this station "2".
You can locate the station more accurately if you first mark the spot with a
tic, a little short line out from the proper spot on the ruler. A sharp pencil
helps too. Wasn't that easy?
If you can do it twice, you can do it thrice. Line 4 gives the instructions on
how to locate station 3. Plot the location of station 3 on your map. Mark it
with an "x" and label it "3". Hopefully that was easy. If you can do it
thrice you can do it a hundred times, or however long it takes to get the job
done.
Plot Line 5. Station 4 should be at the same place as station 0. Or at least
too close to call them different. If there is more that 20 hundredths of a
inch between them, try again.
If you have already tried again, give it up for a few days. You have
blundered, and it should be obvious in hindsight.
If it is already a few days later and you are still making the same mistake,
perhaps it is hopeless. You can send me back my instruments and instructions,
and I'll send you your dollars back. Be sure to enclose the maps which you
have tried to draw so that I can improve my instructions. Or just send me
copies of your maps and whatever else you have done, and I'll straighten you
out. If you have an idea of what went wrong, make a note of it. See the end
of this chapter for my address and phone number.
Everybody else now knows how to plot a map.
SIY1.TXT Plot a Map from a Land Description 77
The CLOSURE ERROR is the distance on the map between two stations which are
supposed to be in the same place. It is a check on the precision, and by
implication, the accuracy of your work.
Precision is like target shooting and getting all the bullets into the same
hole. You have either a good gun rest or a very steady hand. Accuracy is
getting them distributed around the bullseye on the proper target. Your rifle
is properly sighted in.
The closure error is best thought of as a percentage of the run. The RUN is
the distance which you have surveyed around a loop until you used the same
station again for the closing station. Just add up all the tape distances.
The run for the map of the land description in Table 1 is 865.
Measure the distance between station 0 and station 4 on your map. Divide this
by 865 and push the % key. If you have no distance between the stations, you
have 0% closure error. Congratulations.
TABLE 2
Line Station Station COMPASS TAPE Comments
TO FROM quadrants poles
1 10 10 0 0 Stone in Speed's line
2 11 10 S72E 293 3/4 Two white oaks
3 12 11 N37E 123 Corner with Davis & Green
4 13 12 N87W 352 Dogwood in Green's line
5 14 13 S3W 23 The beginning corner
Now look at Table 2. This is the land description of a real parcel of land in
Kentucky. The compass is recorded in quadrants and the distance is in poles.
This is the common land description notation in Kentucky.
You must translate the quadrant notation into the familiar 360 degree
notation. The meaning of the quadrant notation is to face the first direction
(North or South). Then turn the given number of degrees towards the second
direction (East or West). Line 2 has a compass reading of S72E. Set the
compass dial so that the pointer points to S, then turn it towards E for 72
degrees. The reading on your compass dial should be 108.
Now that you know what you are trying to do, you can take a mathematical
shortcut. You can subtract 72 from 180 and get 108.
SIY1.TXT Plot a Map from a Land Description 78
Where did the 180 come from, you ask? Look at your compass. S is 180. N is
360 or 0, whichever is more convenient. E is 90. W is 270.
To translate quadrants, use the following rules.
If the compass direction is a cardinal direction (N, E, S, or W) translate to
([0 or 360], 90, 180, or 270).
If a direction is within a quadrant, do the following with the number of
degrees in the quadrant:
If the quadrant is NE, then add the degrees to 0.
If the quadrant is SE, then subtract the degrees from 180.
If the quadrant is SW, then add the degrees to 180.
If the quadrant is NW, then subtract the degrees from 360.
To translate your normal compass direction (azimuth) into the quadrant system,
use the following rules:
If the direction is a cardinal direction ([360 or 0], 90, 180, or 270), then
translate into (N, E, S, or W).
If the compass direction is greater than 0 and less than 90, then the degrees
are correct and the quadrant is NE.
If the compass direction is greater than 90 and less than 180, then subtract
the degrees from 180, and the quadrant is SE.
If the compass direction is greater than 180 and less than 270, then subtract
180 from the degrees, and the quadrant is SW.
If the compass direction is greater than 270 and less than 360, then subtract
the degrees from 360, and the quadrant is NW.
Play with the compass dial whenever you are in doubt.
Believe it or not, this system made a lot of sense in Antiquity, when the
arithmetic was done by hand. Today it is an anachronism. It's only use in the
present world is to confuse those who would survey it themselves.
A pole is the same as a rod. 16.5 feet. This one made sense in the days
before the invention of the tape measure. But for now, plot at a scale of 100
poles to the inch.
Typical Kentucky land corners are identified under the Comments.
SIY1.TXT Plot a Map from a Land Description 79
Translate the compass readings and plot a map of this survey. You can plot it
on the same graph paper as you used before.
When I plotted a map of the data of Table 2, I really couldn't see any closure
error. Calculating with a hand calculator, I determined the closure error to
be 3.0 poles, or 0.4%. The direction to station 0 from station 4 is 293
degrees. Compare this with the closure error of your plot. Remember, the
percent closure error is the map measured distance between the two stations
representing the same location on the ground, divided by the run around the
surveyed loop, times 100%. You should come out with a closure error of less
than 2%. Anything more is blunder.
A bit more about blunder and error. Error is a small difference of opinion
which sneaks into your measurements. This is due to the unfortunate fact that
the real world isn't mathematically perfect.
Error is part of this method. So far, you have made errors in setting the
declination adjustment, in setting the degrees on your compass dial, in
aligning the compass with north on your map, in placing the compass edge so
that it goes exactly thru the previous station, in setting the beginning end of
the ruler exactly on the station, in guesstimating exactly where some reading
such as 293 3/4 is on the ruler, and finally in getting your pencil in exactly
the right spot. And then there are manufacturing errors in the compass. Plus
a few more I didn't think of.
You can never eliminate all the errors. Just realize that they are there, and
manage them.
Blunders are the *BIG* mistakes. The most common blunder in surveying is to
read the wrong end of the compass. You are going just exactly bassackwards
from where you think you are going. Blunders are obvious when you notice
them. When eliminated, they are gone completely. Except when someone reminds
you of the time when you surveyed for half a day before realizing that your
compass was always pointing toward your new beltaxe!
Blunders, by definition, are big enuf to catch and cure. Always be sure that
your work has built-in blundertraps. When they are not caught, little blunders
become BIG ERRORS.
SIY1.TXT Plot a Map from a Land Description 80
Table 3
TO FROM COMPASS TAPE COMMENTS
20 20 0 0
21 20 122 127 feet
22 21 8 169 feet
23 22 3 103 feet
24 23 86 211 feet
25 24 92 174 feet
26 25 S15E 12 poles
27 26 S14E 5 rods 7 links
28 27 S86W 7 poles 5 links
29 28 S2E 1 chain 32 links
30 29 S86W 13 rods 13 links
31 30 N4W 6 poles 1.5 links
32 31 N8E 3 rods
33 32 278 245 feet closes on 20?
34 33 237 15 feet closes on 20
Table 3 gives you some more practice in plotting a map. Note that the
direction and distance units vary. Translate of all this into degrees and
feet. Plot a map from this land description.
What sort of closure error did you get? What is this in terms of percent
closure error? Is this an acceptable closure error? The actual calculated
closure error is 0.00%. Station 33 was supposed to be the closing station as I
produced these data. The distance for station 34 is my closure error when hand
plotting the map. My hand plotting error was 0.8%, which I consider to be
excessive. That's why I use a computer. And the computer is easier too.
SIY1.TXT Plot a Map from a Land Description 81
Take another look at your map. The closure error should be quite small. Now
look at the boundary of the parcel and think about it. Is it possible to make
a blunder and still have a small closure error? Possible, but not probable.
You are now ready to plot a map of whatever interests you. You may need to
translate the land description into the proper format to plot. Some units of
distance which you may encounter are: a pole or a perch or a rod, 16.5 feet; a
rope, 20 feet; a chain, 66 feet; a link, [a hundredth chain] 0.66 feet; a
furlong, (ten chains) 660 feet; a yard, 3.00 feet; a meter, 3.28 feet; la vara,
2.78 feet (Texas. variable).
If your map comes out too tiny, or if it won't fit on the paper, then you will
have to change the scale of your map. A square plot containing 10 acres has
the length of each side exactly one furlong, or 660 feet. At a scale of 100
feet per inch, the map of that 10 acre square would be 6.6 inches square. This
fits nicely on the graph paper. You might want to plot on a few different
scales just to see what happens. If you run off the graph paper, you can add
another piece to that side. Line up the gridlines. Mark how the two sheets
connect, or tape them together.
You can obtain a copy of a deed for a parcel of land by visiting your Recorder
of Deeds, or whatever title he holds in your county. Just walk into the
courthouse and ask for the deeds.
You will need help finding what you want, so ask. The deeds are indexed in
various ways, depending upon where you are. In Wayne County Kentucky, deeds
are indexed alphabetically by date. Really. I told you that you would need
help!
I find the three little rubber map grippers on the compass to be an annoyance.
They are meant to keep the compass from slipping on the map paper. They work
too well. Just pull them out and stick them onto the compass box with a piece
of sticky tape. You might want them again when using the compass with a topo
map in the field.
If your deed does not give directions and distances, you are out of luck.
There is no way to determine where a boundary given simply as "bounded by John
Dough's property on the south" is, unless it is stated on John Dough's deed.
You will just have to skip drawing a map from the deed.
You may prefer to use a separate circular protractor and ruler for plotting.
But start with the Silva Ranger. Using the Silva for plotting on paper will
teach you how to use it for surveying.
For those of you with land in Township & Range territory, see Chapter 6.
If you have any questions, problems, or comments, write or call me.
Dave Beiter, CAVE Inc, 1/2 Fast Road, Ritner KY 42639. 606/376-3137.
Comments
Post a Comment