214 FORESTRY WORK 



Subsequent measurements, however, prove that the 

 metre has been made too small, so it is now denned as the 

 length of a certain bar of iridio-platinum preserved in 

 the Bureau des Archives, Paris. 



The unit of length is the Metre. 



The unit of area is the Are = 100 square metres. 



The unit of solid measure is the Stere = 1 cubic metre. 



The unit of weight is the Gramme. 



The unit for dry and fluid measure is the Litre. 



The litre = 1 cubic decimetre (^th of a metre) and weighs 

 1 kilogramme = 1000 grammes. 



CALCULATION OF AREAS, ETC. 



Area of square = any side multiplied by itself. 



rectangle = length x breadth. 



parallelogram = base x perpendicular height. 



rhombus or rhomboid ... = base x height. 

 trapezoid (2 sides parallel) = mean length of sides x per- 

 pendicular distance be- 

 tween them. 



trapezium = half the sum of the perpen- 

 diculars x by the diagonal 

 on which they fall. 



triangle = base x perpendicular height. 



equilateral triangle .... = square of side x 0433. 



circle = diameter x -7854. 



= radius x 3-1416. 



= circumference x diameter-^-4. 



= radius x diameter x 1-57. 



ellipse = long axis x short axis x 



0-7854. 



Circumference of circle = diameter x 3-1416 or %?. 



Diameter of circle = circumference x 0-3183. 



equal in area to square = side x 1-1284. 



circumscribing square = side x 1-414. 



Side of square in circle = diam. x 0-7071. 



equal to circle = x 0-8862. 



Solid content of cylinder = area of one end 



x length. 



