Measurement of Area and Volume 23 



the same scale, and each square being ^ its actual 

 size. 



The chief units of area in use in our country are 

 given in the following table, together with their rela- 

 tions to one another and to the square inch. 



Table of Measures of Areas. (British System.) 



144 square inches (sq. in.) =1 sq. foot. 



9 sq. ft. (or 1296 sq. in.) =1 sq. yard. 



4840 sq. yd. (or 6,272,640 sq. in.) =1 acre. 

 640 acres (or 4,014,489,600 sq. in.)=l sq. mile. 



Let us compare this with the table of areas arranged 

 on the decimal system, treating the square centimetre 

 as the unit corresponding to the square inch, thus : 



Table of Measures of Areas. (Decimal System.) 



100 sq. mm. ,, >' "' ... =lsq. cm. 



100 sq. cm. . . . . . . . . =1 sq. dm. 



100 sq. dm. (or 10,000 sq. cm.) . . =1 sq. m. 

 100 sq. m. (or 1,000,000 sq. cm.) . . =1 sq. Dm. 

 100 sq. Dm. (or 100,000,000 sq. cm.) =1 sq. Hm. 

 100 sq. Hm. (or 10,000,000,000 sq. cm.) = l sq. Km. 



Note. In measuring land, the square decametre 

 (=100 sq. metres) is termed the "are", and 100 square 

 decametres make 1 " hectare ". 



On examining the numbers expressing the ratios 

 between successive units in each of the above tables, 

 and also the numbers connecting each unit in the first 

 table with the square inch and in the second table 

 with the square centimetre, the overwhelming sim- 

 plicity of the Decimal system as compared with our 

 own will at once be seen. 



