Shareware Overload Trio 2/Shareware Overload Trio Volume 2 (Chestnut CD-ROM).ISO/dir27/sly13c.zip/SIY8.TXT

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 SIY8.TXT       Measure Acreage                                             39

                                   Chapter 8

                                Measure Acreage

In this chapter, you will calculate the acreage of a property from the map.

You will need:

a) These instructions,

b) Pencil & paper,

c) Common calculator, or hand arithmetic,

d) The maps which you plotted in Chapter 1.

You will NOT need:

a) To believe the seller's word.

The easiest method to use to measure acreage is to simply count the squares.
Yes, there are fancier ways to solve the problem.  Counting squares on a map
has the advantages of simplicity and ease.  No magic.

Get out Graph 1, where you plotted your very first map from the description in
Table 1.  Count the squares within the boundary lines of your map.  If a square
is on the line, count it only if more than half of it lies within the boundary.

Each square is 0.2 inches on a side.  The area of each square is the square of
the side.  0.2 * 0.2 = 0.04 square inches in each square.  To find the area
within the boundary, multiply the number of squares within the boundary times
the area of each square.  This is the area in square inches.

In computerese, the symbol for multiplication is "*", and the symbol for
division is "/".  Since my printer prints in computerese, whatcha see is what
you got.

Check your answer.  Is it reasonable?  Is 413 square inches within the boundary
a reasonable value, or a blunder?

If this were the plot of an actual parcel of land plotted at the scale of 100
feet per inch, then you could calculate the acreage of the land represented.
At 100 feet per inch, the side of each square represents 20 feet on the
ground.  The area of each square represents 20 * 20 = 400 square feet on the
ground.  There are 43,560 square feet in one acre.  Divide the area represented
by one square on the map by the area of one acre, 400 / 43,560.  Thus each
square on the map represents 0.0092 acres.

 SIY8.TXT       Measure Acreage                                             40

Now multiply the number of squares times the part of an acre represented by
each square.  The result is the number of acres inside of the boundary.  I
calculate 1.03 acres.  There is an error associated with this number.  This
error ranges from 1% to 10%, depending upon the quality of your survey.

Now try it with the map drawn from Table 2.  You plotted this map at a scale of
100 poles per inch.  The side of each square represents 20 poles on the
ground.  A pole is a rod is 16.5 feet, so each side is 330 feet.  The area of
each square is 108,900 square feet, or 2.5 acres.

This parcel was bought as 140 acres.  How many acres do you think are there?

This method of the squares works at any scale.  But you must calculate a new
number of acres per square each time that you change either the scale of your
map or the mesh of your graph paper.

You should plot your map so that it covers hundreds of squares.  Smaller maps
may have considerable error from squares on the boundary.  To check for
blunders, mark out a square with sides of 209 feet on your map.  This
represents one acre.

What happens when there is an obvious closure error?  Well, you'll just have to
fudge it.  I usually just draw a line between the closing stations and call
that the boundary.  If I think the error is worth correcting, I draw a triangle
across the map, with one side of the triangle being the closure error.  I then
either add or subtract the area of this triangle, depending upon whether the
closure error underlaps or overlaps.

A better way is to sketch a new version of the map with the error distributed
around the whole loop.  If you have very much error to correct, then you have
blunder, not error.  The cure is to go back and survey it right the next time.

There are mathematical methods to distribute the closure error and measure the
acreage, but they require the use of a computer.  If you have access to a
computer, then use my computer program CAVEMAP1.BAS for the ibm pc.

Calculate the area of the plot of the description of Table 3.

The proper acreage is that calculated from the distances corrected to
horizontal with the clinometer and COS.  The uncorrected acreage will always be
greater than the true acreage.  Perhaps the difference is enuf to be worth
correcting.  You decide.

You will be amused to know that the legal standard for accuracy of acreage for
Kentucky surveyors is plus or minus 10%.  If you can't survey that well
yourself, ask for your "dollars" back.


 SIY8.TXT       Measure Acreage                                             41

There are several other units used for the measurement of land.  The metric
unit (used everywhere but the United States of America) is the hectare.  One
hectare is 100 ares, or 2.47 acres.  The are [pronounced "air"] is 100 square
meters.  A square rod [or perch, or pole] is 272.25 square feet, or 0.00625
acre.  A rood is 40 square perches, or a quarter acre.  A section in Township
and Range territory is one square mile, 640 acres.  A quarter section is 160
acres.  That assumes that the section is not an irregular section.

The acre is 10 square chains, or 43560 square feet.  That is, unless you are
speaking British.  In that case, an acre is 4 roods, which is only 0.999997123
of the American acre or 43559.87471 USA square feet.  If your land is so
valuable that this makes a difference, then you shouldn't be using the compass
and tape method of land surveying.


Dave Beiter
CAVE Inc
1/2 Fast Road
Ritner, KY  42639


606/376-3137