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Some necessary directions concerning surveys in
If you have a large quantity of ground to survey, which consists of many fields or holdings, and that it be required to map and give the respective contents of the same, it is best to make a survey of the whole first, and to be satisfied that it is truly taken, as well as to find its content and as you go round the land, to make a note on the side of your field-book at every station where the boundary of any particular field or holding intersects or meets the surround; then proceed from any one of those stations, and in your field-book say, “ proceed from such a station,” and when you have gone round that field or division, insert the station you close at, and so through the whole : a little practice can only render this sufficiently familiar, and the method of protraction must be evident from the field-notes. When the whole is protracted, and you are satisfied of the closes of the particular divisions, cast up each severally, and if the sum of their contents be equal to the content of the whole first found, you may safely conclude that all is right,
The protraction being thus finished and cast up, transfer it on clean paper, vellum, or parchment, as before: be careful to draw your lines with a fine pen, write on it the names of the circumjacent lands, and set No. 1, 2, 3, 4, &c. in every particular field or division; let every tenant's particular holding be distinguished by a different colored paint being run finely along the boundaries ; let all the roads, rivulets, rivers, bridges, bogs, ponds, houses, castles, churches, beacons, (or what ever else may be remarkable on the ground) be distinguished on the map. Write the title of
the map in a neat compartment either drawn, or done from a good copper-plate graving, with the gentleman's arms.
Prick off one of your parallels with the map, and on it make a mariner's compass, and draw a flower-de-luce to the north, and this will represent the magnetical north; after which set off the variation, which express in figures, and through the centre of the compass, let a true meridian line be drawn of about 3 inches long, by which write True Meridian. Let a scale be drawn, or it is sufficient to express the number of perches to an inch, the map was laid down by. Draw a reference table of three, or, if occasion be, of four or more columns : in the first insert the number of the field or holding : in the next its name and by whom occupied : in the third the quantity of acres, roods, and perches it contains: if you have unprofitable land, as bog or mountain, let the quantity be inserted in the fourth column; and if it be required, you may make another column for statute measure, and then the map is compleated.
The method of dividing land, or of taking off or
inclosing any given quantity..
Plate XII. fig. 1.
Let ABCD, &c. be a map of ground, containing 11 acres, it is required to cut off a piece as DEFGID, that shall contain 5 acres.
Join any two opposite stations as D and G with the line DG (which you may nearly judge to be the partition line) and find the area of the part DEFG, which suppose may want 3R. 20P. of the quantity you would cut off: measure the line DG, which suppose to be 70 perches. Divide SR. 20P. or 140P. by 25, the į of DG, and the quotient 4 will be a perpendicular for à triangle whose base is 70, at the area 140P. Let HI be drawn parallel to DG, at the distance of the perpendicular 4, and from I, where it cuts the boundary, draw a line to D, and that line DI will be the division line ; or a line from G to H will have the same effect; all which must be evident from what has been already said.
But if hills, trees, &c. obstruct the view of the points D and I from each other, it will be necessary, in order to run a partition line, to know its bearing; and it may be proper on some occasions, to have its length; both these may be easily calculated from the common field-notes only, as in the following example without the trouble of any other measurement on the ground, or any dependance on the map and scale.
EXAMPLE II. Plate XII. fig. 3.
Let ABCDEFGHIA be a tract of land, to be divided into two equal parts, by a right line from the corner I to the opposite boundary CD; required the bearing and length of the partition line IÑ, by calculation, from the following field-notes, viz.
IABCI Per.] N. S. E. IA N. 621° W. 59 27.5
52.2 ABN. 19 E.1 188)102.1
35.21 BCS. 77 E. 91
20.5 88.7 CI
71.7 Area, 8722.3 Per. 129.6'129.6 123.9 123.9
Merid. dist. &c.
152A. IR. 25.9P.=24385.9 perch. half, to be divided off,=12192.97
subt. the part I ABCI = 8722.3
= 3470.6 perches.
ICDI Per. N. | S. E. W.
123.9 Area, 6522.1 P.1109.1 109.1 122.9123.9%
Meridian distance, &c.
Then, ICDI : CD :: ICNI : CN i Th. 18
6522.1 :115::9470.6 : 61.19 Sec. 1 which determines the point N in CD.
ICNI Per.] N.
17.7 54.6! 27.8! 54.61
As dif. lat. 54.6 As S. Bear. 61°15' : Radius S. 90 deg : Depart. 99.5 : : Depart. 99.5 :: Radius S.
90 deg : Tang. Bear. 61°15' Distance 113.49
NI runs S. 61 15 W. In the part IABCI, the difference between the northings and the southings of the three lines, IA, AB and BC (109.1) is the difference of latitude, and that of their eastings and westings (71.7) the departure of the line CI, which is placed thereto, so as to balance the columns ; see theo. 1. sect. V. hence the content is obtained, as already taught, without the bearing or length of the line CI.
For the triangle ICDI, the diff. lat. and dep. of IC are taken from the preceding table, which is going from I to C will be northing and easting ; those of CD are found by the bearing and distance, and of DI by balancing the columns, as before for CI.