Measurement of Length 5 



7. For making measurements of short lengths 

 instruments called scales are used. These are flat 

 pieces of steel or wood which have straight parallel 

 edges, along which are marked graduations corre- 

 sponding to certain of the smaller measures of length. 

 Thus, in the scale of a part of which Fig. 1 is a diagram, 

 the top edge is divided into inches by the long marks 

 numbered 1, 2, 3, 4, and these are further divided 

 into halves and tenths of inches by the shorter lines. 

 Along the lower edge is a scale of centimetres sub- 

 divided into half-centimetres and millimetres. The 



TTT[ 







611 , 8 



I , L 



I , 9 



T , Q 



I , 8 



I , 511 III 



Fig. 1. 



scale represented is made of wood, and it will be noticed 

 that the last mark is not placed at the end of the 

 scale. This is done to allow ready measurement to 

 be made starting from the end mark, or "zero", 

 even when the corners of the scale have been rounded 

 off by rubbing while in use. With steel scales this 

 precaution is less necessary, and the graduations on 

 them frequently start at one end of the scale. 



For measuring cloth, a tape-measure is generally 

 employed. This cannot be used for exact measure- 

 ments, as the material of which it is made readily 

 stretches, or in damp weather, shrinks, and hence the 



