Uses of a Line-Divider. 281 
set may be used. The plain rule has two needle-points on its 
underside to prevent it from slipping when placed in any 
Fig. 1. 
position, and on the top has a single line drawn perpendicular 
to its longer edges. 
To divide the line AB into any number of equal parts, say 
seven (fig. 2): slide the plain rule along the divided limb till its 
Fig. 2. 
line coincides with one of the lines of this limb against which 
the number 7 is marked (it is generally best to use the largest 
possible divisions), place the corresponding line on the bevel 
