A treatise on land-surveying; comprising the theory developed from five elementary principles; and the practice with the chain alone, the compass, the transit, the theodolite, the plane table, &cIllustrated by four hundred engravings, and a magnetic chart . (511) To part off a quadrilateral. Let it be required to partoff, by a line running in a ^^g- ^^i- given direction, a quadrila-teral from afield in whichare given the side AB, andthe directions of the twoother sides running from Aand from B. On the ground or platproduce the two convergingsides to meet at some pointE. Calculate the contentof
A treatise on land-surveying; comprising the theory developed from five elementary principles; and the practice with the chain alone, the compass, the transit, the theodolite, the plane table, &cIllustrated by four hundred engravings, and a magnetic chart . (511) To part off a quadrilateral. Let it be required to partoff, by a line running in a ^^g- ^^i- given direction, a quadrila-teral from afield in whichare given the side AB, andthe directions of the twoother sides running from Aand from B. On the ground or platproduce the two convergingsides to meet at some pointE. Calculate the contentof the triangle ABE. Measure the side AE. From ABE subtractthe area to be cut off, and the remainder will be the content of thetriangle CDE. From A set out a line AF parallel to the givendirection. Find the content of ABF. Take it from ABE, and tAus obtain AFE. Then this formula, ED = AE < 7^5^ will fix V FAE the point D, since AD = AE — (512) When the field and the dividing line are given by Bearings, produce the sides as in the last article. Find all the anglesfrom the Bearings. Calculate the content of the triangle ABE, bythe formula for one side and its including angles. Take the cuAP. n.] Parting off Land; 339 desii-ed content from this to obtain CDE. Calculate the side AE = AB^. ThenisAD==AE- /(^ ^ CDE . ;sm, E V \ sin. E . sin. CDE / Example. Let DA bear S. 20^° W.; AB, N. 51^° W., ;J*C. N. 73^-° E.; and let it be required to part off two acres bj afence, DC, runnmg N. 45° W. Am. ABE = sq. chains;whence CDE = sq. chs. Also, AE = ; and finallyAD = — == chains. The scale of Fig. 351 is 5 chams to 1 inch = 1: 3960. If the sum of the angles at A and B was more than two rightangles, the point E would He on the other side of AB. The neces-sary modifications are apparent. (513) To part off any figures Proceed in a similar manner tothat described in Art. (508), by gettin
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Keywords: ., bookcentury1800, bookdecade1870, booksubjectsurveying, bookyear18
