A complete treatise on practical land-surveying, in seven parts; . ed. Afterfinishing the surveying, if you choose, measure the other diagonal, which willenable you to prove your work. (See Problems I. and II. Part I 2.—If a field be very long, or elevated in the middle, so that you cannot seefrom one end to the other, it may be divided into two, or more you may range your lines over the hill, as directed in Part the Fifth. 3.—When two perpendiculars cannot be taken upon either of the diago-nals, such fields must be divided into two triangles by measuring a diagonalfor the ba
A complete treatise on practical land-surveying, in seven parts; . ed. Afterfinishing the surveying, if you choose, measure the other diagonal, which willenable you to prove your work. (See Problems I. and II. Part I 2.—If a field be very long, or elevated in the middle, so that you cannot seefrom one end to the other, it may be divided into two, or more you may range your lines over the hill, as directed in Part the Fifth. 3.—When two perpendiculars cannot be taken upon either of the diago-nals, such fields must be divided into two triangles by measuring a diagonalfor the base of one triangle, and one side of the field for the base of theother. (See Example VI.) 4.—Unskilful surveyors affect to reduce trapeziums into squares, or rect-angles, by measuring all the sides, adding each two opposite sides together,and taking half their sum respectively for a mean length and breadth ; butthis method leads to very erroneous results. (See Part IV. Prob. 2.) EXAMPLES. 1. It is required to survey the trapezium A B C D, and findits Part III.) LAND-SURVEYING. 53 Measure from A toward C. Finding the perpendicular* a Bto rise at 473, and its length 437 links; return, and continuetoward C, till you come to the place where the second perpen-dicular b D rises. There note down its distance from A, 1128links; measure b D = 508 links; then complete the measuringof the diagonal to C, and let the whole be 1490 links. After this, measure the diagonal B D, for a proof-line, whichyou will find 1152 links. 437) 508JPei- .945 diag. 850503780945 2)1408050 Area 7a. Or. 6p. 2. In taking the dimensions of a trapezium, I found the firstperpendicular to rise at 539, and to measure 725 links; thesecond at 1890, and to measure 832 links; the whole diagonalmeasured 2456 links; required the area of the trapezium? Ans. 19a. Or. 19p. 3. The first perpendicular of a trapezium rises at 467, andmeasures 545 links; the second at 1418, and mea
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