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Thus, begin at A, fig. 7, and measure in a straigat line towards C; at a take the perpendicular al, and at m the perpendicular mB. Then measure from C iowards H ; at n take the perpendicular nD, and at o the perpendicular ol.
Next measure from H towards E; at w take the perpendicular wG, and at v the perpendicular vD.
Lastly, measure from E towards G ; and at s take the perpendicular SF.*
To cast up the content, draw a rough figure of the field, and place the dimensions upon the lines as you proceed.
Or, the dimensions being given in the following Fuld-book, required the figure and the content.
• If any of the hedges AB, BC, &c. be crooked, these lines must be met sured and off-sets taken as in Prob. s.
Cut off five figures from the right hand, and the result will be 10:40400 acres = 10 acres, 1 ruod, 24.64 perches.
2. Required the plan and content of an irregular field, from the folo lowing
This field, when constructed, as in fig. 8, is exactly similar to the former one. The content of the off-sets must be found as in Prob. I. Thus,
The area of the whole...... 1040390 Cut off five figures, and the result will be 10-40390 acres = 10 A, 1 R. 24.624 P.
Prob. 5. To survey a large estate.*
If the estate be very large and contain a great number of fields, it cannot be accurately surveyed and planned, by measuring each field separately, and then putting them together; nor by taking all the angles, and measuring the boundaries which enclose it. For, in these cases, the several small errors will be so multiplied, that the differeut fields cannot be correctly laid down in the plan, and the whole figure of the estate will be distorted. Proceed in the following manner.
1. Walk over the estate (wo or three times in order to get a perfect idea of it, or till you can retain the figure of it in your mind. And to assist your memory make a rough draft of it on paper, putting the names of the different fields within
them, and noting down the principal objects.
2. Choose two or more elevated places in the estate, for stations, from which all the principal parts of it can be seen ; and let these stations be as far distant from each other as possible. In selecting the stations, be careful that the lines which connect them may run along
• Emerson's Surveying, page 47, et seq.
the boundaries of the estate, or some of the hedges to which off-sets may be taken when necessary. The smaller the number of stations you have to command the whole, the more exact your work will be, and especially if two or more lines proceed from one station.
3. Take such angles, between the stations, as you think necessary, and measure the distances froni station to station, always in a straight line : these things must be done, till you get as many angles and lines as are sufficient for determining all the points of the stations. In measuring the several station-distances, mark, accurately, where you cross any hedges, ditches, roads, lanes, paths, rivulets, &c. and where any remarkable object is placed, by measuring its perpendicular distance from the station-line; and be particularly careful always to measure in a straight line, which you may determine by taking back. sights and foresights along the station-line with a cross-staff or a theodolite. Also, take off-sets to all the ends of hedges, and to the different bends thereof which may fall near the station-line, and to any pond, house, mill, bridge, &c. noting every thing down that is remarkable ; for these are the data by which the places of such objects are to be determined on your plan.
Be careful to set marks up at the intersections of all hedges with the station-line, that you may know where to measure from when you come to survey the particular fields which are crossed by this line. These fields must be measured as soon as you have completed your station-line, whilst they are fresh in your memory. In this manner all the station-lines must be measured, and the situations of all the adjacent objects determined. It will be proper to lay down the work on paper every night, when you go home, that you may see how you
4. With respect to the internal part of the estate, they must be deternsined in like manner, by new station-lines : for, after the main stations are determined, and every thing adjoining to them, then the estate must be subdivided into two or three parts hy new station-lines ; taking the inner stations at proper places, where you can have the best view. Measure these station-lines as you did the first, and all their intersections with hedges, ditches, roads, &c. also take off-sets to the bends of hedges, and to such objects as appear near these lines. Then proceed to survey the adjoining fields, by taking the angles which the sides make with the station-line at the intersections, and measuring the distances to each corner from these intersections : for every station line will be a basis to all future operations; the situation of every object being entirely dependent on them, and therefore they should be taken of as great length as possible ; and it is best for them to run along some of the hedges or boundaries of one or more fields, or to pass through some of their angles. All things being determined for these stations, you must make more inner stations, and continue to divide and subdivide, till at last you come to single fields ; repeating the same work for the inner stations as the outer ones, till the whole is finished. The oftener you close your work, and the fewer lines you make use of, the less you will be liable to error.
5. An estate may be so situated that the whole cannot be surveyed together, especially if one part cannot be seen from another. In this case, you may divide it into three or four parts, and survey each part separately, as if they were lands belonging to different persons, and at last join them together.
6. As it is necessary to protract and lay down the work as you proceed in it, you must have a scale of a proper length for that purpose. To construct such a scale, measure the whole length of the estate in cbains, then consider how many inches long your plan must be, by these means you will be able to ascertain how many chains to an inch your scale must be, and make it accordingly, or cloose one ready made of the proper dimensions. Ivory scales, chamfered, and graduated close to the edge, are the most convenient.
7. Then trees in every hedge-row should be placed in their proper situations, but these may be taken by guess, in a rough draft, sufficiently exact, being only for ornament; excepting such as are at remarkable places, as at the ends of hedges, at stiles, at gates, &c. and these must be measured. In all the hedges, observe on which side the ditch is situated, and to whom the fences belong.
Erample by the chain and cross-staff. The measurement begins at A, fig. 9, and a direct line is measured to B, in which line every station, intended to be measured from, is carefully marked. Thus at 2* a line is measured to the right, at *3 to the left, at 4* to the right, at *5 to the left, at 6* to the right. Fron B the measurenient continues to C (the mark - shows that it goes to the right), and from C to D, which completes the large triangle DBC; the correctness of the admeasurement is proved by other station-lines, as from g* to 7*, *10 to 6*, and *l1 to 4*.
Again, CB is continued in a straight line to 12, and the measurement proceeds from 12 to 15; this line cannot be laid down on the plan till the distance from *14 to AD is measured, and the admeasurement is checked by measuring from *3 to *13, and from *5 to m. For the other lines see the following Field Book, where the stations measured from are inserted in the left-hand corner, and the stations measured to in the right ; where a hedge is crossed by a station-line nearly at right angles it is marked thus —, when obliquely thus' or thus, when very obliquely thus I, other appropriate marks might have been introduced, but they cannot be expressed conveniently without having types cast for the purpose.
to 4 - Cruss hedge1464 Crosshedge22–
83656 Cross hedge 920 Cross hedge 32 Cross hedge 684 Crosshedge50650/60
From 11 From A 350 48
to 6 3074
to D Cross hedge 1004 Cross bedge36· Cross hedge 2494 Cross hedge
*11 930 9 touch hedge 2072
From '10 400 30
1143 Along hed. to 7 56+30 1170 Cross hedge - - Cross bedge 1004 Touch hedge | From C 7. 401 280
610 34 Along tlie hedge 2574
to C|From 8
to 13 96 1240
940 Cross hedge – 52 +34/1130
44 666 P 34) 860
70 310 From B 601 190
From*310 '13 60 236
to V *512620
1552|180 · Cross hedge 2590 Cross hedge ·
1380 96 | Cross hedge 2210 Cross hedge 1
- Cross hedge 860 Cross hedge – 3/1574
From O tu V. 768P
480 to D 2148 510 to A ; to AD 154140136 to M
1950 Y 14 4120
-80Cross hedge 1836 Cross hedge 3884
6017241 - Cross hedge 3380 Crosshedge60
Cross hedge1080 Cross hedge 2070156
Cross hodge 750 Cross hedge50Cross hedge 1900 Cross hedge. m ||From 14 to AD.
60 1770 160 1320
to T 40 650 80 360
to I From 12 20 1701