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Triangle a A B.

Triangle a DE. a A, 8.70 0.939519 a D, 10.50

1.021189 a B, 10 1.000000 a E, 12

· 1.079181 Sine A a B, 800 9.993351 Sine D a E, 75° • 9.984944

a

Doub. area, 85.67 .

1.932870 Doub. area, 121.7 - 2.085314

a

Triangle a BC.

Triangle a EF. a B, 10 1.000000 a E, 12

1.079181 C, 11.40. 1.056905 a 8.78

. 0.943495 Sine B a C, 27° 9.657047 Sine Ea F. 55° • 9.913365

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Doub. area, 51.75 - 1.713952 Doub. area, 86.31

1.936041

Triangle a CD.

Triangle a FA a C, 11.40 1.056905 | a F, 8.78

0.943495 a D, 10.50 . 1 021189 a A, 8.70

• 0.939519 Sine C.a D, 780 9.990404 Sine Fa A, 450 . 9.849485

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TO SURVEY A FIELD FROM SOME ONE OF THE ANGLES, FROX

WHICH THE OTHERS MAY BE SEEN.

From the stationary angle, take the bearing and distance to each of the other angles, with a compass and chain.

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Draw a meridian line to pass through the stationary angle as at F.

From the point F, lay off the bearing and distance to the several angles, and connect them by lines, as FG, FA, FB, &c.

The area may be calculated as taught in the preceding

CASB,

CASE VII.

TO SURVEY A FIELD FROM TWO STATIONS WITHIN TAL

FIELD, PROVIDED THE SEVERAL ANGLES CAN BE SEEN FROM EACH STATION.

Find the bearing from each station to the respective angles; and also the bearing and distance from one station to

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First Station.

Second Station. A C. N. 380 30' E.

BC. S. 82° 0' E. A D. S. 69

O E.

BD. S. 17 0 E. A E. S. 59 0 W. BE. S. 28 0 W. AF. N. 63 0

BF. S. 49 0 W. A G. N.

21

0 W. BG. N. 76 0 W. A H. North.

BH. N. 24 0 W.
Stationary line A B. N. 14° E. 20 chains.

W.

TO PROTRACT THIS FIELD.

a

At the first station A, draw a meridian line, and lay off the bearings to the respective angles; draw the stationary line A B, according to the bearing and distance; at B draw a meridian line parallel to the other, and lay off the bearings to the angles, as taken from this station ; from each station draw lines through the degree which shows the bearing of each angle, as marked by the protractor or line of chords, and the points where those lines intersect each other will be the angles of the field. Connect those angular points together by lines, and those lines will represent the several sides of the field.

CASE VIII.

TO SURVEY AN INACCESSIBLE FIELD.

field, from each of which the several angles may be seen; from each station take the bearing of the angles; and take the bearing and distance from one station to the other.* FIELD BOOK. See Fig. 59.

Fig. 59.
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W.

A

B

S
First Station.

Second Station.
A E. N.
Ε
9° 15' E.

BE. N. 50° 0' W. A F. N. 16 0 E.

BF. N. 29 15 W.
A G.
N. 14 30 E.

BD. N. 24 0
A D.
N. 39 0 E.

BG. N. 21 30 W. A H. Ν. 40 0 E.

BH. N. 5 0 E. A C. N. 72 0 E.

BC. N. 20 30 E.

Ch. L.
Stationary distance AB. S. 88° 30' E. 19.20.

44. The directions given in the last CASE for plotting the field, will apply in this CASE also; and the area in this and the ceding case may be calculated in the manner pointed out in Case IV. by dividing the plot into triangles, and measuring diagonals and perpendiculars. Or the sides may be found by trigonometry, and the area calculated arithmetically, as already taught

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CASE IX.

TO SURVEY A FIELD WHERE THE BOUNDARY LINES ARR VERY IRREGULAR, WITHOUT NOTICING WITH THE COMPASS EVERY SMALL BEND.

Fig. 60.

E

D

Begin near one corner of the field, as at A, Fig. 60, and measure to the next large corner, as B, in a straight line; noticing also the bearing of this line. From the line take offsets to the several bends, at right angles from the line; noti. cing in the FIELD BOOK at what part of the line they are taken, as at A 1, H2, I3, B 4. Proceed in the same manner round the field. In the figure, the dotted lines represent the stationary lines, and the black lines the boundaries of S the field.

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Draw the stationary lines according to the directions in CASE IV. From A make an offset of 56 links to I; measure from A to H 540 links, and make the offset, H 2, 140 links; measure from A to I 826 links, and make the offset I 3, 36 links; at B make the offset B 4, 36 links. Proceed in the same manner round the field, and connect the ends of the offsets by links, which will represent the boundaries of the field.

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