WEIGHTS AND MEASURES 



9 



For convenience in carrying in the pocket, foot rules 

 (Fig. 3) are often made with hinged joints so that they fold 

 into a short length (4 in. or 6 in.) 

 and longer rules are made in 



FIG. 3. Folding Rule. 



multiples of a foot. Formerly FIG. 2. A Machinist's Rule. 



the most common rule used by 



mechanics was the folding 2-ft. boxwood rule. Present- 



day mechanics also use this rule largely, but where greater 



lengths are to be measured the zigzag folding rule is more 



commonly employed. This latter rule folds into 6-in. 



sections and may be obtained in 

 any length up to 10 or 12 feet. 

 The yardstick (3 ft. long), sub- 

 divided into feet, inches, and frac- 

 tions of an inch, is also frequently 

 used as a unit of measure, es- 



pecially for the measurement of textiles. 



In building construction and timber measurements a 



10-ft. pole is often employed. It is usually divided into 



1-ft. sections, with the first foot subdivided into inches and 



fractions of an inch. Long objects, such as steam pipes, 



shaft lines, buildings, etc., are usu- 



ally measured with a steel tape (Fig. 



4). For ordinary purposes tape 



measures are made of various ma- 



terials, such as linen braid or steel 



ribbon, in different lengths, and 



are graduated either in eighths or 



sixteenths of an inch. The gradua- 



tions are printed on the braid, 



and the better grades are woven with wire selvages 



or edges to prevent stretching. Spring-tempered steel- 



FIG. 4. Steel Tape. 



