3. To find the area of any quadri- 

 lateral figure, or figure of four sides : 



Multiply the length of its diagonal 

 B D by half the sum of the perpendicu- 

 lars A F and C E drawn to it from the 

 opposite angles A and C. 



Example Required the contents of a field, whose 

 diagonal is 6*36 ; and the perpendiculars to it from the 

 opposite angles, 1'50, and 4'90. 



6-36 



3-20 half the sum of the perpendiculars. 



12720 

 1908 



2-03520 

 4 



14080 

 40 



5-63200 



Ans. 



A. R. P. 

 205 



4. To find the area of a farm of many sides : 

 Divide it into quadrilateral figures and triangles, 



measure these separately ; then add all together. 



5. To survey a field with crooked hedges : 



Measure straight lines adjacent to the hedges, and from 

 these lines measure such offsets to the hedges as will suf- 

 fice to compute tiie actual space between the straight 

 lines and the hedges. 



2. OF THE VARIOUS KINDS OF MEASURE. 



Though all our surveys of land are expressed in acres, 

 roods, and perches, yet these terms are often used to de- 

 note very unequal quantities according to the measure 

 used. 



There are three measures in ordinary use, viz., Statute 

 or Imperial measure, Cunningham or Scotch measure, and 

 Irish or Plantation measure. 



