[Fig. 159] shows an improved section liner which can be adjusted to any angle, and will space the parallel lines at any desired regular distance.
Fig. 159.
IRREGULAR CURVE OR SCROLL.
Irregular curves, or, as they are sometimes termed, sweeps, represented by [figs. 160-166], are used for curves that cannot be put in by the other instruments. They are very useful when elliptical or parabolic curves are desired, in preference to circles or arcs of a circle. They are much used in design and architectural drawing. They are made of thin hardwood or rubber, and sometimes of horn.
Figs. 160-166.
Fig. 167.
Fig. 168.