MEASUREMENT OF LAND. 



45 



When the field is a trapezium or a trapezoid. 



Trapezium. Trapezoid. 



RULE. Divide it diagonally by a line running from 

 one extreme corner to the other, which will cut the field 

 into two triangles ; then proceed with each as in the fore- 

 going rule, and add the areas of the two triangles together. 

 The product will be the number of acres. 



Where the field is an irregular polygon. 



RULE. Draw diagonals to divide the field into tri- 

 angles; find the area of each separately, and the sum of 

 the whole will be the number of acres. 



NOTE. There are very few fields or lots which cannot 

 be measured by cutting them into triangles, and proceed- 

 ing by the above rule. In fact, all straight-sided fields 

 can be so measured. 



