A piece of ground in Lower Dublin Township, Philadelphia County, belonging to George Vandergrift. Pennsylvania Method. 3 2 OFF-SETS are perpendiculars measured from the angular points of the land, to the stationray distance on either side thereof; to do which, observe the following RULE. Rule a table, as hereafter exemplified; take the bearing of the line from which off-sets are to be made, and from this line make off-sets at right angles to each angular point on either side; set the distance to each offset under the head of Base, and the distance of each offset, under that of Perpendicular. Then, to find the area of these off-sets, Set the firt base opposite to station 1, in the column headed Bases, and take the first base from the second, the second from the third, &c. and set the remainders, respectively, in said column; each of which will be the distance between the respective perpendiculars. Then add the first and second perpendiculars together, the second and third, third and fourth, &c. and set their sums respectively, in the column marked Sum of Perpendiculars. Then each of these numbers, multiplied in its respective base, will give the double area of the quadrilateral figure, and triangle, (by Problems 6 and 9, pages 107 and 110. |