Measurement of Length 3 



4. In dealing scientifically with any subject, sim- 

 plicity is one of the most important points to keep in 

 view. Hence for all scientific work, and in many 

 countries for general use as well, a system of units 

 has been adopted which does not involve much of the 

 unnecessary labour, e.g. in memorising tables, and in 

 making lengthy calculations, required by the British 

 system. This is the " Metric " or " Decimal " system, 

 introduced in 1795 by the newly-born French Republic. 

 It is based on the system of numeration in common 

 use among civilised peoples, in which the relative 

 positions of the figures in a number indicate their 

 respective values. Thus 5555 expresses the sum of 

 5 thousands, 5 hundreds, 5 tens, and 5 ones, each 

 5 having a distinct value dependent on its place. 

 Fractions of the unit are shown by placing a dot after 

 the figure in the unit's place in the number, e.g. 5*5 

 denotes the sum of 5 units and 5 tenths of one unit. 

 The standard of length chosen by the French Govern- 

 ment was the Metre. This is defined as " the distance 

 between the ends of a bar of platinum, preserved in 

 the Court of Archives at Paris, when the bar is at the 

 temperature of melting ice, i.e. C." The metre is 

 longer than the yard, being 39'37. . . inches. The mul- 

 tiples and submultiples of the metre are arranged in 

 accordance with the decimal system so that each is 

 exactly one-tenth of that next higher in value. Thus 

 the table of metric measures of length is as follows : 



10 millimetres (mm.) =1 centimetre. 



10 centimetres (cm.) =1 decimetre. 



10 decimetres (dm.) =1 METEE. 



10 metres (m.) =1 decametre. 



10 decametres (Dm.) =1 hectometre. 



10 hectometres (Hm.) =1 kilometre (Km.). 



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